Cost effectiveness analyses (CEAs) of bariatric procedures are critical given the cost of the procedures, their potential for saving future costs related to comorbid health conditions and worker productivity and the growing population of operative candidates. Economic evaluations of bariatric procedures have so far been limited9
, with only one formal CEA of bariatric procedures5
evaluating RYGB, and none for LRYGB and LAGB. LAGB is increasing in popularity, has minimal operative mortality compared with LRYGB but less is known about its weight loss efficacy over time and in the community at large. Furthermore there have been only a few small, comparative studies of LAGB and LRYGB10
. The main elements influencing the cost effectiveness of these procedures is associated weight loss and postoperative morbidity. Since these procedures have different rates of adverse and perhaps positive outcomes, comparing them can be problematic. CEA is an ideal methodology to balance these two sets of outcomes. Using this analytic tool probability and cost estimates associated with competing management strategies (using actual and modeled data) can be used to compare different strategies with an overall metric of cost/QALY. In this study we found that both bariatric procedures were cost-effective at less than $25,000 for all base-case scenarios. This finding was similar to those of previous CEAs5, 11
We also found that LAGB was more cost-effective than RYGB, with lower ICER compared to non-operative interventions and in certain populations LAGB was cost saving. The benefits of LAGB were related to its lower associated mortality rate and dependent on it having significant and sustained weight loss over time.
A major component of a cost-effectiveness analysis is the determination of the survival benefit of the intervention. When evaluating survival benefits of obesity surgery, the mortality rate associated with the procedure is balanced against a long-term survival benefit. In a population based study, the 30-day mortality rate of gastric bypass in Washington State was nearly 2%, twice the highest mortality rate previously reported9
. However, patients surviving the first postoperative year had a significant survival benefit over non-operated patients. Researchers reported at the 2006 International Congress on Obesity16
that RYGB results in 40% less chance of mortality rate than matched non-operated cohorts. This was also exemplified in a retrospective study with 9-year follow-up that showed overall annual mortality of 1% among 154 patients that underwent RYGB compared with 4.5% annual mortality among 78 morbidly obese patients referred for RYGB who did not undergo the operation for personal or financial reasons12
. Utilizing a modeled analysis of survival benefit, Pope and colleagues13
reported a 2.3–2.6 year and 3.3–3.4 year gain in life expectancy for women and men, respectively, aged 30–60 years undergoing RYGB.
On the other hand, LAGB has very low perioperative mortality (<1%, ), but may have a lower extent of excess body weight loss compared to RYGB in the first 3 years after placement. In a recent retrospective series, patients that underwent LRYGB had 66% excess weight loss after 3 years versus 39.3% in LAGB14
. There was no difference in excess body weight loss between LRYGB and LAGB 5 years after the operation (58.6% vs. 49%, P=0.84), however the researchers conceded that low patient follow-up at 5 years makes true comparison faulty. Two research abstracts presented at the 2006 International Congress on Obesity indicated a 62–73% reduction in mortality for LAGB patients compared to a matched cohort15
. These reports suggest LAGB may extend survival in a fashion similar to RYGB. In our modeled analysis we found that despite a lower extent of weight loss in LAGB, it was more cost-effective than LRYGB. A recent systematic review of the weight loss achieved with different procedures16
, showed similar percentage of excess body weight loss with LAGB and RYGB. However, most of these studies are flawed by limited number of patients with long-term follow up beyond 3 years. We assessed the cost effectiveness of these procedures with varying weight loss using a two-way sensitivity analysis ().
Two-way sensitivity analysis of cost-effectiveness of LAGB and LRYGB
Cost is a main issue for the broader use of bariatric surgery. Although the benefits of bariatric surgery on weight reduction and the impact on obesity-related comorbidities have been shown, many health insurance companies are limiting the use of these procedures. While the cost of bariatric surgery needs to be evaluated, the cost of non-operative intervention including diet, exercise and medication also needs to be considered when directing healthcare policy. Reportedly, Americans spend over 92 billion dollars annually on obesity-related healthcare, including non-surgical interventions, all of which have been shown to be ineffective over time3
. Our research group recently compared the costs of operative and non-operative interventions and found that the operative interventions are cost savings when applied to a population of morbidly obese patients17
Clinicians and purchasers of healthcare services are engaged in a discussion to determine the best approach to the treatment of obesity. Cost and effectiveness are some of the elements that help determine this issue but all healthcare decisions should be individualized to the unique needs of the patient and practice environment. Finally, the results of a cost effectiveness analysis may not be a good argument for the health insurance companies in the United States since many insurance contracts are terminated within 3–4 years. Given that limited timeline, some have suggested that from a business perspective coverage of a bariatric procedure would be like sustaining the “upfront” costs of the operation and its complications without the long-term benefits of the reduced healthcare costs due to the weight loss and reduction in obesity related comorbidities. When taken from the broader perspective of the Federal and State governments and large employers (who finance most healthcare costs in the United States) these economic considerations are relevant to the competing crises of spiraling healthcare costs and the loss of productivity related to obesity.
This study has several limitations. Future costs, life expectancy and quality of life are based on the weight loss achieved by the procedures. While for RYGB there are studies with 7 year follow up, there are only a few studies reporting the weight loss of LAGB after 3 years. We assumed that following the initial 3 years after surgery the BMI remains stable. Weight gain after this period will reduce the cost effectiveness of the procedures. In order to make conservative estimate of the cost-effectiveness of the bariatric procedures, patients undergoing non-operative management were assumed to have a stable BMI. The estimates of life expectancy, future costs and quality of life are based on data from the NHANES III and the Framingham studies. These studies include data on BMI up to 37.5. We assumed a linear correlation between the BMI and these parameters (life expectancy, future costs and quality of life) for estimation for BMIs of 40–60. Data on life expectancy supports this linear relationship18
, but data on BMI greater than 45 is limited. This may represent a conservative bias if the outcomes for patients with higher BMIs are worse than the linear projection we assumed. Furthermore, the probabilities and costs that underlie this model are not BMI or age specific because there are few reports that suggest that probabilities and costs are related to BMI or age. However, if these probabilities and costs are associated with advancing BMI or age then the model may underestimate the impact of these on patients with advanced BMI or age and the implication of this bias is difficult assess. In this study we considered the relationship between obesity and 5 chronic conditions: hypertension, hypercholesterolemia, type 2 diabetes mellitus, coronary heart disease and stroke. Results of previous research19
suggest that these conditions account for approximately 85% of the total economic burden of obesity. This may also represent a conservative bias since other comorbid conditions not considered in this model may be reduced by weight loss. Finally, although our model incorporated complications of surgery in the usual care cost calculation, rates of these complications may vary between sites and may be difficult to assess accurately in a modeled analysis