The long-term cost-effectiveness of bariatric surgery for the treatment of severe obesity: a cost utility analysis from a societal perspective

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1 The long-term cost-effectiveness of bariatric surgery for the treatment of severe obesity: a cost utility analysis from a societal perspective Presented By: Erica Lester MD MSc

2 Disclosure I have no actual or potential conflict of interest in relation to this topic or presentation.

3 4-6 billion annually in Canada, estimates (2011) 4% health budget Reduced home/workforce productivity, life expectancy, quality of life, social programs Numerous interventions: lifestyle therapies, medications and surgery

4 Cost Effectiveness Generalizable to Canada?

5 What is the cost-effectiveness of bariatric surgery for the treatment of extreme obesity? In a pragmatic, Canadian context?

6 Methods

7 APPLES study Data The Alberta Population-based Prospective Evaluation of the Quality of Life Outcomes and Economic Impact of Bariatric Surgery (APPLES) study 500 extremely obese adults, all meeting NIH criteria Enrolled in multidisciplinary obesity management clinic Allocated to surgical, medical or no direct therapy treatment arms Data captured prospectively at 0, 6, 12, 18 and 24 months Interview/survey, clinical data cross-linked with administrative data

8 Empirical Data demographics anthropometrics comorbidities/medical history: (Hypertension, Diabetes etc) health related quality of life (EQ5D-3L) Occupation/time off work enrollment in government support programs (ex: short term disability) Patient borne costs Health care usage

9 Health Care Costs Ambulatory care in-patient care physician billing prescription and over-the-counter medication patient out-of pocket costs

10 Measurement of Patient Bourne Costs Medications (prescription and over the counter) transport assistance household care personal care mobility aids meal replacements physical trainers exercise programs nutrition programs diet programs private nursing care Physical therapy occupational therapy respiratory therapy other

11 Perspectives Public Health Payer Perspective: -inpatient/outpatient care costs, physician billing, prescription and over-the- counter medication, patient out-of pocket costs Societal Perspective -productivity loss (friction method) and health payer perspective costs

12 2 years Calculated costs and effects directly from APPLES data Surgery Therapy 2 year Cost/Effect Obesity Therapy Medical Therapy 2 year Cost/Effect Wait-listed Therapy 2 year Cost/Effect

13 >2 years to Lifetime HTN No Comorbidity Surgical Therapy DMDN HTN/DM Death

14 Extrapolating health states beyond 2 years Of mortality: Canadian mortality rates, varied by age/cycle and comorbidity status Of resolution of Hypertension/Diabetes: parametric survival analysis and Swedish Obesity Study Of acquiring Hypertension: Framingham Model Of acquiring Diabetes: Public Health Agency of Canada, adjusted for obesity class

15 Extrapolating Costs and Utility Quality of life: -Eq5D-3L scores extrapolated from data, compared to data from HCQA Costs: Public Health Payer Perspective: -costs associated with 2 nd year therapy minus therapy/study related costs (post-operative visits, medical visits at time intervals) Societal Perspective -friction approach: 2 nd year costs (until age retirement)

16 Discount & Sensitivity All costs and effects discounted at 5% 3% and 0% in sensitivity analysis Sensitivity Analysis: Deterministic, Scenario and Probabilistic analysis Treeage Pro 2011 All costs expressed in 2016 Canadian Dollars

17 Results

18 At 2 years, Surgery greatest QALY and Cost Public Health Payer Perspective Absolute Cost Incremental Cost Absolute QALY gain Incremental QALY gain ICUR (compared to lowest cost option) Wait list Medical Therapy ,822 Surgical Therapy , ,794

19 At 2 years, Surgery greatest QALY and Cost Societal Approach Absolute Cost Incremental Cost Absolute QALY gain Incremental QALY gain ICUR (compared to lowest cost option) Medical Therapy 39, Wait list 51,016 11, dominated Surgical Therapy 51, ,872

20 Sensitivity Analysis, Societal Perspective

21 Lifetime Time horizon, Bariatric Surgery Cost Effective Absolute Cost Incremental Cost QALY Incremental QALY ICER Health Care Perspective Wait list Surgical Therapy Medical Therapy dominated

22 Lifetime Time horizon, Bariatric Surgery Cost Saving Absolute Cost Incremental Cost QALY Incremental QALY ICER Societal Perspective Surgical Therapy Medical Therapy dominated Wait List dominated

23 Surgery Becomes most favorable at a WTP of $5000

24 PSA Lifetime Societal Evaluation

25 Results robust to Deterministic Sensitivity Analyses and Scenario Analyses Alternative Eq5D data Additional costs year prior surgery Lower costs medical/wait listed comorbid patients Cost of death Rate acquiring comorbidity Mortality Discount

26 Results robust to Deterministic Sensitivity Analyses and Scenario Analyses Alternative Eq5D data Additional costs year prior surgery Lower costs medical/wait listed comorbid patients Cost of death Rate acquiring comorbidity Mortality Discount

27 Substituting costs for comorbid wait-listed patients alters results Alternative costs for diabetic and hypertensive waitlisted patients Control Group Surgical Therapy Medical Therapy Dominated

28 Change in WTP threshold controls (waitlisted) to surgical treatment

29 When Compared to no therapy or medical therapy Health System Perspective At WTP $50,000, Surgery is cost effective at year 5 Surgery cost > wait list cost, but is more cost effective then medical therapy NMB $100,566 Societal Perspective At WTP $50,000, Surgery becomes cost effective at year 7 Surgery cost < wait list cost (becomes cost saving) at year 21 NMB $122,854

30 Discussion Despite parameterization to favor medical/no therapy, bariatric surgery is cost effective (ex lowest rate acquisition diabetes) Broaden perspective, surgery becomes cost saving Friction approach vs Human capital approach: Transfer payments and other potential societal costs Extrapolation with robust, high quality data Pragmatic approach Results robust to sensitivity analysis

31 Next Steps Real world data + Model Subgroup analysis Triaging and Prioritizing: constrained maximization (optimize who gets what therapy) External validation

32 Conclusions Bariatric Surgery is cost effective, when considered from both a health care and a societal perspective; The magnitude of effectiveness increases with timehorizon and from the broader perspective.

33 Thank you

34 Incremental Cost at 2 years No Therapy Health Care Perspective $2554 $13,822/QALY Medical Therapy $14,872 $109,794/QALY Surgical Therapy

36 Cost Effectiveness Bariatric Surgery At WTP $50,000 Health System Perspective Societal Perspective Societal Perspective=Cost Saving

37 Mean Change in BMI, Utility Percent Change Comorbidities Wait List Medical Therapy Surgical Therapy Mean Change BMI in kg/m (2.2) -2.5 (4.5) -7.4 (5.6) Mean Change EQ-5D 0.005(0.131) 0.073(0.135) 0.054(0.146) Resolution of Hypertension,% 3.0% 11.9% 28.3% Resolution of Diabetes,% 5.3% -3.8% 50.7%

38 APPLES Results

39 Lifetime Model Sensitivity Analysis HC-1 Additional Year of Cost, Surgery Therapy Control Group Surgical Therapy Medical dominated Alternative Eq5D data Control Group Surgical Therapy Medical Therapy dominated

40 Lifetime Model Sensitivity Analysis HC-2 Discount rates 3% Control Group Surgical Therapy Medical therapy dominated 0% Control Group Surgical Therapy Medical Therapy dominated

41 Lifetime Model Sensitivity Analysis SC-1 Additional Year of Cost, Surgery Therapy Surgical Therapy Medical Therapy dominated Wait List dominated Alternative Eq5D data Surgical Therapy Medical Therapy dominated Wait List dominated Alternative costs for diabetic and hypertensive waitlisted patients Control Group Surgical Therapy Medical Therapy Dominated

42 Lifetime Model Sensitivity Analysis SC-2 Discount rates 3% Surgical therapy Medical therapy dominated Control Group dominated 0% Surgical therapy Control Group dominated Medical therapy dominated

43 Model at 10 years 10 year model Base Case Publicly funded health care system perspective Wait list Medical Therapy Surgical Therapy Societal Perspective Medical Therapy Surgical Therapy Wait list

44 Transition Probabilities Source Variables used in determination Assumptions Mortality All patients Statistics Canada(23) Age, sex Patients exhibit same mortality probability regardless of comorbidity or BMI: conservative Diabetes resolution Surgical APPLES Age, sex SOS Medical and Waitlisted SOS - Diabetes acquisition All patients SOS study(14) Public Health Agency of Canada(19, 20) Ganz et al(18) BMI Baseline Canadian risk corresponds to obesity class 1: treatment arm rates adjusted for obesity class Hypertension resolution Surgical APPLES, compared to Age, sex SOS Medical and Waitlisted SOS - Assumed both groups had cure rate of zero Hypertension acquisition All patients Framingham Risk Model(15, 38) Public Health Agency of Canada(16) Shuger et al(17) Age, sex, blood pressure, smoking status, BMI Assumed no parental hypertension

45 Results-2 year Absolute Cost Incremental Cost Absolute Incremental ICER QALY gain QALY gain Health Care Perspective Wait list Medical Therapy ,822 Surgical Therapy , ,794 Societal Perspective Medical Therapy 39, Wait list 51,016 11, dominated Surgical Therapy 51,125 11, ,872 WTP:$50,000

46 NIH Criteria for Bariatric Surgery BMI > 40 or >35 with comorbidity Failure of non-operative treatment Absence of contraindications Well informed, compliant, motivated patient

49 2 years Calculated costs and effects directly from APPLES data Surgery Therapy Alive Dead 2 year Cost/Effect Obesity Therapy Medical Therapy Alive Dead 2 year Cost/Effect Wait-listed Therapy Alive Dead 2 year Cost/Effect

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