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A Comparison of the Cost-Effectiveness of Lifestyle Interventions in Pregnancy

  • Cate Bailey
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
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  • Helen Skouteris
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia

    Warwick Business School, Warwick University, Coventry, England, UK
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  • Cheryce L. Harrison
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
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  • Briony Hill
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
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  • Shakila Thangaratinam
    Affiliations
    World Health Organization Collaborating Centre for Global Women’s Health, Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, England, UK
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  • Author Footnotes
    ∗ Helena Teede and Zanfina Ademi contributed equally to this work and share joint senior authorship.
    Helena Teede
    Footnotes
    ∗ Helena Teede and Zanfina Ademi contributed equally to this work and share joint senior authorship.
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia

    Monash Health Endocrine and Diabetes Units, Monash Health, Melbourne, Australia
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  • Author Footnotes
    ∗ Helena Teede and Zanfina Ademi contributed equally to this work and share joint senior authorship.
    Zanfina Ademi
    Correspondence
    Correspondence: Zanfina Ademi, PhD, School of Public Health and Preventive Medicine, Faculty of Medicine Nursing and Health Sciences, Monash University, 553 St Kilda Rd, Melbourne, Australia 3004.
    Footnotes
    ∗ Helena Teede and Zanfina Ademi contributed equally to this work and share joint senior authorship.
    Affiliations
    School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
    Search for articles by this author
  • Author Footnotes
    ∗ Helena Teede and Zanfina Ademi contributed equally to this work and share joint senior authorship.
Open ArchivePublished:September 18, 2021DOI:https://doi.org/10.1016/j.jval.2021.07.013

      Highlights

      • Although lifestyle intervention in pregnancy effectively reduces excess gestational weight gain and adverse pregnancy outcomes, limited research has yielded inconsistent findings on cost-effectiveness. It is also unclear which types of lifestyle interventions are the most cost-effective.
      • The meta-analysis on which this study is based has generated level 1 evidence of the efficacy of lifestyle interventions by intervention type in gestational weight gain and maternal and neonatal outcomes. The current cost-effectiveness study builds on this and shows that physical activity interventions appear cost saving and that diet and diet with physical activity interventions are likely to be cost-effective dependent on willingness-to-pay thresholds over a short time horizon and based on maternal pregnancy outcomes alone. Mixed interventions (lacking structured diet or physical activity intervention components) were not cost-effective. Scenario analysis, when diet-only, diet with physical activity, and physical activity-only interventions were analyzed, appeared cost saving. When neonatal intensive care unit costs were added to the model, all intervention types were cost saving except for mixed interventions.
      • These results favor implementing lifestyle interventions in pregnancy that incorporate structured diet and physical activity components at the population level.

      Abstract

      Objectives

      Lifestyle interventions during pregnancy improve maternal and infant outcomes. We aimed to compare the cost-effectiveness of 4 antenatal lifestyle intervention types with standard care.

      Methods

      A decision tree model was constructed to compare lifestyle intervention effects from a novel meta-analysis. The target population was women with singleton pregnancies and births at more than 20 weeks’ gestation. Interventions were categorized as diet, diet with physical activity, physical activity, and mixed (lacking structured diet and, or, physical activity components). The outcome of interest was cost per case prevented (gestational diabetes, hypertensive disorders in pregnancy, cesarean birth) expressed as an incremental cost-effectiveness ratio (ICER) from the Australian public healthcare perspective. Scenario analyses were included for all structured interventions combined and by adding neonatal intensive care unit costs. Costs were estimated from published data and consultations with experts and updated to 2019 values. Discounting was not applied owing to the short time horizon.

      Results

      Physical activity interventions reduced adverse maternal events by 4.2% in the intervention group compared with standard care and could be cost saving. Diet and diet with physical activity interventions reduced events by 3.5% (ICER = A$4882) and 2.9% (ICER = A$2020), respectively. Mixed interventions did not reduce events and were dominated by standard care. In scenario analysis, all structured interventions combined and all interventions when including neonatal intensive care unit costs (except mixed) may be cost saving. Probabilistic sensitivity analysis showed that for physical activity and all structured interventions combined, the probability of being cost saving was 58% and 41%, respectively.

      Conclusions

      Governments can expect a good return on investment and cost savings when implementing effective lifestyle interventions population-wide.

      Keywords

      Introduction

      Interventions to improve diet and physical activity behaviors in pregnancy can mitigate the impact of the obesogenic environment that affects women’s health worldwide.
      Obesity. World Health Organization.
      ,
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      Women are increasingly entering pregnancy at higher than recommended weight and gaining weight in excess per guidelines.
      Institute of Medicine and National Research Council Committee to Reexamine IOM Pregnancy Weight Guidelines
      Committee to re-examine IOM pregnancy weight guidelines.
      In Australia, approximately 15% of pregnant women are expected to develop gestational diabetes mellitus (GDM), and these women are likely to have a higher incidence of hypertensive disease in pregnancy.
      Incidence of gestational diabetes in Australia. Australian Institute of Health and Welfare.
      As well as affecting the health of women and their offspring, GDM and hypertensive disease in pregnancy have a high cost burden on healthcare systems, estimated at $1.3 billion for GDM and $1.03 billion for preeclampsia in the United States.
      • Dall T.M.
      • Yang W.
      • Halder P.
      • et al.
      The economic burden of elevated blood glucose levels in 2012: diagnosed and undiagnosed diabetes, gestational diabetes mellitus, and prediabetes.
      ,
      • Stevens W.
      • Shih T.
      • Incerti D.
      • et al.
      Short-term costs of preeclampsia to the United States health care system.
      Large cost savings could potentially be generated by reducing the incidence of these 2 conditions, and recent evidence has shown that antenatal lifestyle interventions can limit gestational weight gain and prevent adverse events including GDM and cesarean birth.
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      Before recommending implementation and translation of these interventions, health economic analysis is needed to inform healthcare providers and policy makers.
      In our previous systematic review of lifestyle interventions in pregnancy with an existing economic analysis, we were unable to determine overall cost-effectiveness because the few interventions evaluated were largely ineffective.
      • Bailey C.
      • Skouteris H.
      • Teede H.
      • et al.
      Are lifestyle interventions to reduce excessive gestational weight gain cost effective? A systematic review.
      We subsequently conducted a modeling study based on the intervention costs from a specific effective intervention,
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      using the intervention effects from a large systematic review.
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      Results suggested that antenatal lifestyle interventions were likely to be cost-effective, with higher cost-effectiveness for higher body mass index (BMI) groups. In this modeling study, we were able to capture the overall impact of all interventions combined but not to investigate separate interventions to determine which yielded better value for money.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      To be able to investigate different intervention types, we updated our previous systematic review and meta-analysis of randomized controlled trials of antenatal lifestyle interventions published in 2017, initially used in our modeling study.
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      The revised systematic review captures 117 randomized controlled trials of antenatal lifestyle interventions, categorized into 4 intervention types (diet, diet with physical activity, physical activity, and mixed) allowing comparative cost-effectiveness analysis across intervention types.
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      Diet interventions in the updated review
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      were structured, typically presented by a dietitian and recommended a specific diet or types of foods. Physical activity interventions were structured, usually with 2 to 3 exercise classes per week over 15 to 26 weeks, delivered by a trained instructor. Diet with physical activity interventions included at least 1 structured diet and physical activity component. Mixed interventions lacked articulated structured diet and physical activity components (eg, unstructured, written lifestyle guidance that may include weight monitoring).
      When implementing interventions in real-world settings, policy makers need reliable information on cost-effectiveness to appropriately allocate scarce resources.
      • Elliot R.
      • Payne K.
      Essentials of Economic Evaluation in Healthcare.
      Thus, understanding which types of interventions are more cost-effective is essential for policy decision making. In this study, we aimed to explore cost-effectiveness based on the data from the 117 studies recently captured in our systematic review
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      across clinically prioritized maternal and neonatal outcomes and across these 4 different intervention types. This knowledge will underpin the implementation and scale-up of lifestyle interventions in pregnancy.

      Methods

      Overview of Outcomes and Model

      We conducted a cost-effectiveness analysis using the decision tree model developed for our previous study.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      Three maternal outcomes were investigated as prioritized by clinicians and experts in a Delphi study
      • Fong F.
      • Rogozinska E.
      • Allotey J.
      • Kempley S.
      • Shah D.K.
      • Thangaratinam S.
      Development of maternal and neonatal composite outcomes for trials evaluating management of late-onset pre-eclampsia.
      : GDM, hypertensive disorders in pregnancy, and cesarean delivery. The incremental cost-effectiveness ratio (ICER) was defined as the cost per case prevented, with cases being GDM and hypertensive disorders in pregnancy and incorporating the effects of birth type (cesarean delivery and/or induction). We included 4 health states: developed GDM, developed a hypertensive disorder in pregnancy, developed both GDM and a hypertensive disorder in pregnancy, or developed neither GDM nor a hypertensive disorder in pregnancy. For each health state, 4 birthing outcomes were modeled: cesarean delivery, induction with vaginal birth, induction with cesarean delivery, and neither induction nor cesarean delivery. The decision tree model is shown in Appendix Figure 1 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013. Outcomes were considered from the perspective of the public healthcare system. The time horizon covered early pregnancy (trials generally started around the end of the first trimester) to birth (hospital stay post normal stay for the birth was not included); hence, discounting was not required.

      Population

      To define the baseline (standard care), a deidentified data set from the largest health service network in Australia was used that included routine maternity care outcomes such as GDM, hypertensive disorder in pregnancy, and type of birth, as outlined in our previous publication (no subgroups were excluded from the data set).
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      The population included in this data set can be considered representative of the general Australian population and includes high ethnic and socioeconomic diversity.
      • Abell S.K.
      • Suen M.
      • Pease A.
      • et al.
      Pregnancy outcomes and insulin requirements in women with type 1 diabetes treated with continuous subcutaneous insulin infusion and multiple daily injections: cohort study.
      Data were available for the years from 2009 to 2013 for singleton pregnancies with a birth of more than 20 weeks’ gestation. During this time, the GDM diagnostic criteria matched most closely to those used in the meta-analysis lifestyle intervention studies. BMI was categorized according to the World Health Organization recommendations.
      In brief, there were 38 052 cases in the health-center data set (there were 1 499 326 births in Australia between 2008 and 2013
      Births, Australia. Australian Bureau of Statistics.
      ), of which 54% of women were categorized as having a BMI less than 25 kg/m2, 27% had a BMI from 25 to 30 kg/m2, and 20% had a BMI greater than 30 kg/m2. Mean age was 29.7 years (SD 5.43), most women spoke English as their first language (70%), 56% of pregnancies were multiparous, and 83% of women did not smoke.
      Using national guidelines for diagnosis,
      • Nankervis A.
      • McIntyre H.D.
      • Moses R.
      • et al.
      ADIPS consensus guidelines for the testing and diagnosis of gestational diabetes mellitus in Australia. Australasian Diabetes in Pregnancy Society.
      7.5% of women received a diagnosis of GDM. Rates of hypertensive disorder in pregnancy were 3.8%, and 0.5% of women had both conditions. Cesarean birthrates were 27.8%, and inductions were 21.9%. Mode of birth by health status has been previously published.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      Approval for the analysis of the health network data set was attained from the Monash Health Human Research Ethics Committee (Approval14001Q).

      Standard Care

      Between 2009 and 2013, routine antenatal care received by women in the health network data set included generic written resources that were either mailed at booking or provided at the booking visit, usually at approximately 16 weeks’ gestation. It consisted of recommendations for occasional weight monitoring plus provision of information on food safety, hygiene, and national dietary guidelines. Women did not receive lifestyle or dietary interventions during pregnancy.

      Lifestyle Intervention Effects

      The mean intervention effect for each intervention type compared with standard care was obtained from a large, recently updated meta-analysis.
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      Classification of intervention type was conducted independently by an experienced dietitian, exercise physiologist, and endocrinologist/public health physician. Interventions were categorized as structured diet, diet with physical activity where at least 1 component was structured, structured physical activity, and mixed (lacking structured diet and physical activity components). To account for the intervention effect, risk ratios were calculated from odds ratios as per our previous publication,
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      with odds ratios sourced from the recent meta-analysis (HT). Risk ratios, 95% confidence intervals (CIs), and distributions are presented in Table 1 for health states and birth outcomes.
      Table 1Key input parameters for effects and costs for GDM, HDP, both GDM and HDP, cesarean delivery, and induction, by intervention type, including parameter variation and distribution.
      Risk ratiosBase95% confidence intervalDistribution
      LowerHigher
      Diet
      GDM0.6560.4990.847Lognormal
      HDP0.82120.4981.291Lognormal
      Both
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.
      0.6560.4990.847Lognormal
      Cesarean delivery1.0490.9191.197Lognormal
      Induction1
      Diet with physical activity
      GDM0.7490.5770.965Lognormal
      HDP0.7640.5521.052Lognormal
      Both
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.
      0.7490.5770.965Lognormal
      Cesarean delivery0.9680.7921.172Lognormal
      Induction1
      Physical activity
      GDM0.6240.4950.768Lognormal
      HDP0.6750.4970.906Lognormal
      Both
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.
      0.6240.4950.768Lognormal
      Cesarean delivery0.8790.7940.961Lognormal
      Induction1
      Mixed
      GDM1.0250.9411.122Lognormal
      HDP1.1241.0001.263Lognormal
      Both
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.
      1.0250.9411.122Lognormal
      Cesarean delivery0.9860.9231.053Lognormal
      Induction1
      All
      GDM0.8140.7310.904Lognormal
      HDP0.8800.7671.009Lognormal
      Both
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.
      0.8140.7310.904Lognormal
      Cesarean delivery0.9560.9101.007Lognormal
      Induction1
      Costs A$Base−30%30%
      Antenatal GDM costs10557381371Gamma
      Antenatal GDM and HDP costs278119473616Gamma
      Antenatal HDP costs192313462500Gamma
      Intervention costs228160296Gamma
      Vaginal birth costs581240687555Gamma
      Cesarean delivery costs11 416799214 841Gamma
      Induction and vaginal birth7846549210 200Gamma
      Induction only203414242645Gamma
      Note. Risk ratios for “both GDM and HDP” were set to those for GDM. Risk ratios were not available for induction. A merged group was created to capture all structured diet, physical activity, and diet with physical activity interventions.
      GDM indicates gestational diabetes mellitus; HDP, hypertensive disorders in pregnancy.
      Data for both GDM and HDP were modeled on GDM outcomes because this outcome was not measured in the meta-analysis.

      Lifestyle Intervention Costs

      To estimate average intervention costs, we sourced information on intervention components from the studies in the meta-analysis where GDM, hypertensive disorders in pregnancy, and/or cesarean delivery outcomes were included. Data were extracted for the following: (1) practitioner type, (2) contact minutes, and (3) whether delivered individually or in groups. Three assumptions were made to account for missing information. First, if delivered by group but group size was not stated, it was assumed as 10 in the base case. Group sizes of 6 or 15 were investigated in scenario analyses. Second, cost per hour for the health professional delivering the intervention was obtained from Medicare Benefits Schedule (MBS) data
      MBS Online - Medicare Benefits Schedule. Department of Health, Australian Government.
      (MBS data provide costs of health services funded by the Australian Government in the context of a universal, freely accessible public health system). Costs for fitness instructors were not included in the MBS schedule and were sourced from the Fitness Australia Award Pay Guide. Third, where session length was not available, we assumed 60 minutes for initial individual visits, 30 minutes for subsequent individual visits, and 45 minutes for group classes. We estimated home visits at 90 minutes to include travel time. Follow-up phone calls were estimated at 20 minutes. Despite these assumptions, there was insufficient information to calculate costs in 10 interventions.
      • Renault K.M.
      • Nørgaard K.
      • Nilas L.
      • et al.
      The Treatment of Obese Pregnant Women (TOP) study: a randomized controlled trial of the effect of physical activity intervention assessed by pedometer with or without dietary intervention in obese pregnant women.
      • Polley B.A.
      • Wing R.R.
      • Sims C.J.
      Randomized controlled trial to prevent excessive weight gain in pregnant women.
      • Herring S.J.
      • Cruice J.F.
      • Bennett G.G.
      • Rose M.Z.
      • Davey A.
      • Foster G.D.
      Preventing excessive gestational weight gain among African American women: a randomized clinical trial.
      • Li Q.
      • Cui H.
      • Zheng D.
      • Li N.
      • Chang L.
      • Liu C.
      Effects of walking exercise during late trimester on pregnancy outcome of low-risk primipara.
      • Vinter C.A.
      • Jensen D.M.
      • Ovesen P.
      • Beck-Nielsen H.
      • Jørgensen J.S.
      The LiP (Lifestyle in Pregnancy) study: a randomized controlled trial of lifestyle intervention in 360 obese pregnant women.
      • Phelan S.
      • Phipps M.G.
      • Abrams B.
      • Darroch F.
      • Schaffner A.
      • Wing R.R.
      Randomized trial of a behavioral intervention to prevent excessive gestational weight gain: the Fit for Delivery Study.
      • Van Horn L.
      • Peaceman A.
      • Kwasny M.
      • et al.
      Dietary approaches to stop hypertension diet and activity to limit gestational weight: maternal offspring metabolics family intervention trial, a technology enhanced randomized trial.
      • Wolff S.
      • Legarth J.
      • Vangsgaard K.
      • Toubro S.
      • Astrup A.
      A randomized trial of the effects of dietary counseling on gestational weight gain and glucose metabolism in obese pregnant women.
      • Thornton Y.S.
      • Smarkola C.
      • Kopacz S.M.
      • Ishoof S.B.
      Perinatal outcomes in nutritionally monitored obese pregnant women: a randomized clinical trial.
      • Assaf-Balut C.
      • García De La Torre N.
      • Durán A.
      • et al.
      A Mediterranean diet with additional extra virgin olive oil and pistachios reduces the incidence of gestational diabetes mellitus (GDM): a randomized controlled trial: the St. Carlos GDM prevention study.
      Costs for patient pathways and unit costs are presented in the Appendix Tables 1 to 4 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013. Average intervention costs by category were A$168 for diet, A$187 for diet with physical activity, A$217 for physical activity, A$184 for mixed, and A$198 for all interventions combined. Interquartile range and minimum and maximum costs by intervention type are presented in Appendix Table 5 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013.

      Public Healthcare Costs

      Costs of patient care in the public health system were outlined in our previous publication.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      In brief, we developed patient pathways for GDM, hypertensive disorders in pregnancy, and cesarean delivery to approximate the type and nature of services that women were likely to access. Patient pathways were developed using clinical guidelines and policies, published articles, and multidisciplinary expert opinion. Antenatal care, associated costs, and medication costs were sourced from the MBS
      MBS Online - Medicare Benefits Schedule. Department of Health, Australian Government.
      and the Pharmaceutical Benefits Scheme.
      Schedule of Pharmaceutical Benefits. Department of Health, Australian Government.
      Birthing costs were estimated from published Diagnosis-Related Group information on medical costs in Australia from 2015 to 2016
      National Hospital Cost Data Collection, Public Hospitals Cost Report, Round 20 (Financial Year 2015-16). Independent hospital pricing authority (IHPA).
      and adjusted to 2019 prices using the health price index.
      Health expenditure Australia 2016-17. Australian Institute of Health and Welfare.
      Input parameters for costs are additionally presented in Table 1 (note that neonatal intensive care unit [NICU] costs were not included in the base-case analysis but are considered in the third scenario analysis).

      Scenario Analysis

      Scenario analysis 1

      Group size was an important indicator of intervention costs in physical activity and mixed interventions; the group size, however, was not stated in 26 of the 43 interventions with physical activity components. In the base case, a class size of 10 was used if not otherwise stated. In this scenario analysis, 2 further models were conducted assuming 6 persons per group and 15 persons per group.

      Scenario analysis 2

      In the meta-analysis,
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      a sensitivity analysis was conducted in which data for structured interventions across diet, diet with physical activity, and physical activity interventions were analyzed together. In scenario 2, we used the risk ratios from this combined analysis. Risk ratios for the overall structured intervention data were as follows: GDM (and both GDM and hypertensive disorders in pregnancy) (0.670 [95% CI 0.582-0.765]), hypertensive disorders in pregnancy (0.737 [95% CI 0.600-0.889]), and cesarean birth (0.929 [95% CI 0.856-1.008]). Average intervention costs across these structured intervention categories over the time horizon were A$203.

      Scenario analysis 3

      In the base case, we included costs for maternal outcomes (GDM, hypertensive disorders of pregnancy, and cesarean delivery). A third scenario analysis was conducted to measure the effect of admission to NICU, which was not considered in the base-case analysis. Total average weighted NICU costs were estimated from 8 Diagnosis-Related Group codes relating to neonatal costs
      National Hospital Cost Data Collection, Public Hospitals Cost Report, Round 20 (Financial Year 2015-16). Independent hospital pricing authority (IHPA).
      (see Appendi Table 6 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013 for further information on the codes). The percentage differences between intervention and standard care groups for NICU costs were calculated from the actual percentage of events in the meta-analysis. The cost of NICU was estimated at A$76 621 per admission. NICU costs were added to baseline costs and ICERs calculated.

      Sensitivity Analysis

      Deterministic sensitivity analysis

      One-way sensitivity analysis was used to estimate the impact of uncertainty around effect and cost parameters for analyzing structured interventions together. Risk ratios were varied by 95% CIs and costs by ±30%.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      ,
      • Blank P.R.
      • Ademi Z.
      • Lu X.
      • Szucs T.D.
      • Schwenkglenks M.
      Herpes zoster vaccine: a health economic evaluation for Switzerland.

      Probabilistic sensitivity analysis

      To explore combined parameter uncertainty, probabilistic sensitivity analysis was conducted (10 000 iterations) and displayed on a cost-effectiveness plane. Risk ratios were varied by 95% CIs and cost by ±30%. In line with our previous study,
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      we used gamma distributions for cost inputs and lognormal distributions for effects.

      Statistical Analysis

      Health-center data were analyzed using Stata version 15 (StataCorp LLC, College Station, TX). Decision tree models were built in Microsoft Excel (Microsoft Corporation, Redmond, WA). ICERs were calculated, representing cost per case (GDM, hypertensive disorder in pregnancy, or both) prevented and accounting for birth type (vaginal, cesarean, induction). @RISK software version 7.5 in Excel was used for probabilistic sensitivity analyses.

      Results

      Comparison of 4 Intervention Types on Key Maternal Outcomes

      Effect and cost differences and ICERs were calculated for each intervention type, as shown in Table 2. For physical activity interventions, there was a 4.2% difference in effects between groups, and the intervention was likely to be cost saving (58.4% of pairs lay in the southeast quadrant suggesting higher effects and lower costs). In the diet-only and diet with physical activity interventions, there were 3.5% and 2.9% differences in effects between groups, respectively, with cost differences of A$169 and A$59 per person, respectively. ICERs were A$4882 for diet and A$2020 for diet with physical activity interventions (northeast quadrant). Mixed interventions had limited efficacy between intervention and standard care groups (−0.07%), with a cost difference of A$182 per person and an ICER of −A$27 020, thus dominated by standard care. Comparisons between the intervention groups are presented on a cost-effectiveness plane in Figure 1.
      Table 2Effects (percentage of complications avoided), costs, and ICERs with 95% CI from PSA comparing standard care with intervention by intervention category for maternal outcomes.
      Effects (% of complications avoided)Costs (A$)ICERQuadrant, %
      InterventionStandard careDifference (95% CI)InterventionStandard careDifference (95% CI)(95% CI)NWNESESW
      Diet8.3211.783.4684178248169A$48820.170.0429.50
      (1.31-5.25)(−405 to 1001)(−A$12 502 to A$27 711)
      Diet with PA8.8811.782.908307824859A$20200.370.129.60
      (1.31-4.22)(−988 to 787)(−A$36 376 to A$31 764)
      PA7.5511.784.2381538248−95Dominant041.758.40
      (2.85-5.44)(−1474 to 830)(−A$36 015 to A$20 344)
      Mixed12.4611.78−0.6884318248182Dominated----
      (PSA not conducted)
      Because of the very small effect size causing a large ICER, it was not possible to run probability sensitivity analysis and obtain CIs or quadrant percentages for these estimates.
      All9.8411.781.948323824875A$3855059.140.90
      (1.10-2.70)(−493 to 445)(−A$29 138 to A$25 415)
      CI indicates confidence interval; dominant, cost saving; ICER, incremental cost-effectiveness ratio; NE, northeast – higher costs, higher effects; NW quadrant, northwest - higher costs, lower effect (dominated); PA, physical activity; PSA, probabilistic sensitivity analysis; SE, southeast - lower costs, higher effects (dominant); SW, southwest - lower costs, lower effects.
      Because of the very small effect size causing a large ICER, it was not possible to run probability sensitivity analysis and obtain CIs or quadrant percentages for these estimates.
      Figure thumbnail gr1
      Figure 1Cost-effectiveness plane comparing diet, PA, diet with PA, mixed, and all interventions combined. △Cost and △outcome pairs: diet: A$169, 3.46%; diet with PA: A$59, 2.90%; PA: A$−95, 4.23%; mixed: A$182, −0.68%; all: A$75, 1.94%.
      GDM indicates gestational diabetes mellitus; HDP, hypertensive disorders in pregnancy; PA, physical activity.

      Scenario Analysis

      Scenario analysis 1

      We estimated 10 participants per class in the base case where class size was not stated and 6 per class and 15 per class size in this scenario analysis. Results are shown in Appendix Table 7 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013. Changing the class size for the physical activity interventions had the largest effect on the ICER; physical activity interventions, however, remained cost saving. Diet with physical activity classes varied but remained in the northeast quadrant. Diet-only and mixed interventions were unaffected (as they did not include physical activity classes).

      Scenario analysis 2

      In scenario 2, data for structured interventions across diet, diet with physical activity, and physical activity interventions were analyzed together. Effects here were 8.2% compared with 11.8% for standard care with a cost difference of 3.6% (95% CI: 2.73, 4.49). Costs were A$8240 for the intervention group and A$8248 for the standard care with cost saving of A$8 (95% CI: −911, 601). The ICER was dominant (cost-saving) at A$ −217 (95% CI: −25 583, 16 732). Forty-one percent of values in the PSA fell in the North-East quadrant and 59% in the South-East quadrant.

      Scenario analysis 3

      To understand the additional impact of NICU admission on the ICER, we added NICU costs for intervention and standard care groups, whereas all other parameters remained the same. When NICU costs were added, all ICERs were in the southeast quadrant (cost saving), except for the mixed interventions that were in the northwest quadrant (dominated) as shown in Table 3.
      Table 3Percentage of NICU admissions, costs of NICU, and total costs by intervention and standard care groups and ICERs to add the costs and effects of NICU into the model.
      InterventionStandard careCostEffectICER
      % NICUCost NICU, A$Costs,
      Overall costs per base case from Table 3 ICER.
      A$
      Total, A$% NICUCost NICU, A$Costs,
      Overall costs per base case from Table 3 ICER.
      A$
      Total, A$Difference, A$Difference
      Effect difference as in Table 3.
      Diet6.34827841713 2448.96819824815 067−18233.46Dominant
      Diet with PA12.49501830717 80813.09961824818 209−4012.90Dominant
      PA3.62758815310 9115.03831824812 079−11684.23Dominant
      Mixed22.517 240843125 67122.715 860824824 1081563–0.68Dominated
      All15.912 183832320 50615.611 953824820 2013051.94A$157
      ICER indicates incremental cost-effectiveness ratio; NICU, neonatal intensive care unit; PA, physical activity.
      Overall costs per base case from Table 3 ICER.
      Effect difference as in Table 3.

      Sensitivity Analysis

      Deterministic sensitivity analysis

      Deterministic (one-way) sensitivity analysis was conducted on all interventions combined (including mixed). The tornado graph is presented in Figure 2. The most influential parameters in the one-way sensitivity analysis were risk ratios and costs of cesarean delivery, intervention costs, GDM and hypertensive disorders of pregnancy risk ratios, and vaginal birth costs. Tornado graphs for diet, diet and physical activity, and physical activity are shown in Appendix Figures 2 to 4 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013. The cesarean delivery risk ratio had the highest effect on each of these intervention types.
      Figure thumbnail gr2
      Figure 2Summary of the deterministic sensitivity analysis results presented in a tornado chart. Blue bars represent lower limit values. Gray bars represent upper limit values.
      Cesarean indicates cesarean birth; CI, confidence interval; GDM, gestational diabetes mellitus; HDP, hypertensive disorders in pregnancy.

      Probabilistic sensitivity analysis

      Probabilistic sensitivity analyses were conducted for each intervention type separately (diet, diet and physical activity, physical activity) and all interventions combined. The cost-effectiveness plane with 10 000 iterations using gamma distributions for costs and log normal distributions for effects is presented in Table 2 and Figure 3. In addition, cost-effectiveness acceptability curves were presented in Appendix Figures 5 to 8 in Supplemental Materials found at https://doi.org/10.1016/j.jval.2021.07.013. For physical activity interventions, the probability of being cost saving was 54% compared with 28% for all interventions combined. For scenario 2, the probabilistic sensitivity analysis for all structured interventions (diet, diet and physical activity, physical activity) combined indicated a 95% CI of −A$29 284 to A$23 886, with 50.8% of values lying in the northeast quadrant and 49.2% of values in the southeast quadrant.
      Figure thumbnail gr3
      Figure 3Cost-effectiveness plane demonstrating the probability of cost-effectiveness with 10 000 iterations using gamma distributions for costs and lognormal distributions for effects of diet, physical activity, and diet plus physical activity compared with standard care.

      Discussion

      There is now a clear, level 1 evidence of the efficacy of lifestyle interventions in improving gestational weight gain and reducing adverse pregnancy outcomes.
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      Here, we modeled the cost-effectiveness of antenatal lifestyle interventions over a short time horizon in terms of preventing common maternal adverse outcomes (GDM, hypertensive disorders in pregnancy, and cesarean delivery). In the base case, structured physical activity interventions may be cost saving, and structured diet and “diet with physical activity” interventions may be cost-effective, dependent on willingness-to-pay thresholds. Mixed interventions were not cost-effective, with the ICER situated in the northwest quadrant (less effective, more costly). In scenario analysis, when structured interventions across diet, diet with physical activity, and physical activity interventions were analyzed together, these interventions appeared cost saving. When NICU costs were added to the model, all intervention types appeared cost saving except for mixed interventions (which were not cost-effective). These findings suggest that lifestyle interventions in pregnancy including structured diet, structured physical activity or diet, and physical activity with at least 1 component being structured are likely to be cost saving or cost-effective.
      Previous cost-effectiveness studies on antenatal lifestyle interventions have been largely negative, mainly because of inadequate sample size and failure to demonstrate individual study intervention efficacy on pregnancy outcomes.
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      ,
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      This study was based on the a priori model developed in our earlier research for maternal adverse events reliant on a more limited meta-analysis
      International Weight Management in Pregnancy (i-WIP) Collaborative Group
      Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials [published correction appears in BMJ. 2017 Aug 23;358:j3991].
      ,
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      and estimated intervention costs from only 1 lifestyle intervention.
      • Harrison C.L.
      • Lombard C.B.
      • Teede H.J.
      Limiting postpartum weight retention through early antenatal intervention: the HeLP-her randomised controlled trial.
      Here, we significantly advance knowledge by applying results from an updated meta-analysis on 117 trials
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      and comparing ICERs across a range of intervention types using the average of costing from individual interventions. The ICER for all interventions was A$1470 in our previous analysis
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      and A$3855 in the current analysis; differences were due to updated risk ratios in the meta-analyses and more reliable intervention cost estimates (we modelled all interventions and compared 4 intervention types over a larger pool of interventions). These results strongly support the cost-effectiveness of antenatal lifestyle interventions applying structured diet, physical activity, or diet and physical activity interventions.
      The deterministic sensitivity analysis suggested that cesarean delivery costs and effects had a large influence on cost-effectiveness in the model. Because cesarean delivery was experienced by 28% of women (similar to approximately 30% of births Australia-wide
      National core maternity indicators. Australian Institute of Health and Welfare.
      ), costs for cesarean deliveries were likely to have a significant impact. We also found that there was a significant effect on cesarean delivery rates from lifestyle interventions during pregnancy in the meta-analysis results.
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      Intervention costs also had a strong influence on the model, suggesting that the cost of delivering a lifestyle intervention at a population level needs to be carefully considered. Risk ratios for GDM and hypertensive disorders in pregnancy contributed to uncertainty, as did hospital costs for vaginal births. The probabilistic sensitivity analyses showed that CIs were wide; these results reflect highly variable costs in the real world.
      A key consideration in this analysis was that the model was limited to the clinical prioritized maternal outcomes, excluding neonatal outcomes. We have included the neonatal outcome of NICU in scenario analysis; however, future models may be able to include outcomes specific to the different intervention categories. For example, structured diet has the greatest impact on gestational weight gain and GDM, preterm delivery, large for gestational age, NICU admission, and total maternal and neonatal adverse outcomes.
      • Teede H.
      • Bailey C.
      • Moran L.
      • et al.
      Effect of antenatal lifestyle interventions including diet and physical activity on gestational weight gain and pregnancy outcomes: a systematic review and meta-analysis.
      Diet also reduced gestational weight gain by approximately 20%, which was more than physical activity alone. The effect of diet may influence postpartum weight retention, long-term obesity, and noncommunicable disease risk, with additional anticipated cost benefits. Finally, the model did not include broader maternal or neonatal benefits in pregnancy or outcomes over the longer term, such as prevention of maternal and childhood obesity and noncommunicable diseases. Including these approaches may improve the cost-effectiveness demonstrated here, as our results are likely to have underestimated the cost benefits of antenatal lifestyle interventions due to not having included these factors. Once long-term efficacy data are available, these outcomes would be important to include in future studies.
      Implementation and scale-up of the most effective lifestyle programs into routine healthcare have now been funded in Australia. The authorship team has influenced national guidelines for healthy lifestyle support in routine care,
      Physical activity and exercise guidelines for all Australians for pregnancy. Department of Health.
      and partnerships are in place with broad health services and implementation research underway.
      • Goldstein R.F.
      • Walker R.E.
      • Teede H.J.
      • Harrison C.L.
      • Boyle J.A.
      The healthy pregnancy service to optimise excess gestational weight gain for women with obesity: a qualitative study of health professionals’ perspectives.
      Early results suggest high efficacy and strong support from clinicians and women and high feasibility, with publications currently under review.

      Strengths and Limitations

      The strengths of this study were that the intervention effect was based on a large meta-analysis, intervention costs were estimated from more than 70 interventions, and estimates of the prevalence of complications were from a large health network data set. Nevertheless, a limitation was that interventions may differ substantially both within and across categories. Further research from our team is ongoing to determine which intervention components are most effective, which intervention types work for whom, and in what circumstances. Notably, owing to the nature of the aggregated study data in the meta-analysis, subanalysis by BMI category was not feasible. Subgroup analysis by BMI category was undertaken in our previous modeling publication where we found that interventions were more likely to be cost saving or cost-effective at higher weight.
      • Bailey C.
      • Skouteris H.
      • Harrison C.L.
      • et al.
      Cost effectiveness of antenatal lifestyle interventions for preventing gestational diabetes and hypertensive disease in pregnancy.
      Because actual costs for each intervention were not available, we estimated costs based on information supplied in each article on practitioner time in intervention delivery; however, 10 interventions could not be assessed because of insufficient information. Costs and effects may be less reliable for diet interventions because the effect estimates were based on only 9 interventions and costs on only 6 interventions. Costing patient pathways for each complication type was based on published data, guidelines and clinical expertise, but was challenging because of the large range of possible costs associated (for instance, a case of hypertensive disorder in pregnancy may result in an early induction with little extra cost or in prolonged costly hospital stays). Nonetheless, the cost estimates reflect real-world clinical scenarios. Finally, the model did not include broader benefits over the longer term, such as neonatal outcomes or maternal obesity and noncommunicable diseases, which are important for future studies.

      Conclusion

      Structured antenatal diet, physical activity, or diet with physical activity interventions appear cost saving or cost-effective based on willingness-to-pay thresholds when only clinically prioritized, short-term maternal outcomes are considered. Notably, we leveraged efficacy data on lifestyle interventions from a recent systematic review and meta-analysis of 117 intervention studies and estimated cost of each intervention. Other neonatal and longer-term benefits were not included in the model, suggesting that cost-effectiveness is likely to have been underestimated. These results support the implementation and scale-up of lifestyle interventions in pregnancy at the population level to improve the health of women and the next generation. This work is now extensively funded by the Australian Government and underway.

      Article and Author Information

      Author Contributions: Concept and design: Bailey, Skouteris, Hill, Teede, Ademi
      Acquisition of data: Bailey, Harrison, Thangaratinam, Teede, Ademi
      Analysis and interpretation of data: Bailey, Teede, Ademi
      Drafting of the manuscript: Bailey, Teede, Ademi
      Critical revision of manuscript for important intellectual content: Bailey, Skouteris, Harrison, Hill, Thangaratinam, Teede, Ademi
      Statistical analysis: Bailey, Teede, Ademi
      Provision of study materials or patients: Harrison, Teede
      Obtaining funding: Skouteris, Teede, Ademi
      Administrative, technical, or logistic support: Harrison, Thangaratinam, Teede
      Supervision: Hill, Skouteris, Teede, Ademi
      Conflict of Interest Disclosures: Dr Bailey reported receiving the Australian Government Research Training Program (RTP) Scholarship during the conduct of this study. Drs Hill and Teede reported receiving grants from the National Health and Medical Research Council during the conduct of the study. No other disclosures were reported.
      Funding/Support: Funding for this research has been provided from the Australian Government’s Medical Research Future Fund (MRFF). The MRFF provides funding to support health and medical research and innovation, with the objective of improving the health and well-being of Australians. MRFF funding has been provided to The Australian Prevention Partnership Centre under the MRFF Boosting Preventive Health Research Program. Further information on the MRFF is available at www.health.gov.au/mrff. The UK National Institute for Health Research supported the iWIP research.
      Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
      Ethics: No ethics approval was required.

      Acknowledgment

      We acknowledge Assistant Professor Emily Callander, Professor Danny Liew, Dr Catherine Keating, Clara Marquina, Dr Melanie Llloyd and the Monash Outcome Research and Health Economics team (MORE) for their support in completing this project.

      Supplemental Material

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