Comparison of 4-Year Health Care Expenditures Associated With Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy

Key Points Question Do the 4-year health care expenditures associated with Roux-en-Y gastric bypass (RYGB) differ from those associated with sleeve gastrectomy? Findings In this population-based, matched cohort study of 1624 patients receiving either RYGB or sleeve gastrectomy in Ontario, Canada, there was no statistically significant difference in mean health care expenditures between RYGB and sleeve gastrectomy 4 years after the procedures ($33 682 vs $33 948, respectively). Meaning These results may help to inform patients, surgeons, and policy makers on the relative values of RYGB and sleeve gastrectomy.


Introduction
Recognition that pharmacotherapy and lifestyle changes alone will not produce clinically significant, sustainable weight loss has fueled increasing demand for bariatric surgery. 1 Compared with no surgery, long-term randomized 2 and nonrandomized 3 evidence has shown durable outcomes over time after bariatric surgery. Five-year follow-up of 2 randomized clinical trials 4,5 has also shown similar body weights, rates of type 2 diabetes remission, and reoperation rates among patients randomized to RYGB vs sleeve gastrectomy, the 2 most common bariatric procedures. These findings are in contrast to those from 2 large observational studies from the US 6,7 that found relatively lower reoperation and reintervention rates with sleeve gastrectomy in the 5 years after bariatric surgery.
However, few studies have compared the long-term health care expenditures associated with the 2 procedures. As such, the relative cost-effectiveness of the 2 procedures is unknown, which is an important gap in knowledge, because several countries (eg, Canada, United Kingdom, Australia) require both clinical and cost-effectiveness evidence for public reimbursement of health care technologies. The primary objective of this study was to compare the 4-year health care expenditures of matched cohorts of patients undergoing RYGB vs sleeve gastrectomy in a universal, publicly insured health care system. Our hypothesis was that health care expenditures would be similar in the 2 groups during the 4 years after surgery. Secondary objectives were to identify factors independently associated with 4-year health care expenditures and to compare RYGB and sleeve gastrectomy in terms of subsequent hospitalizations, bariatric procedures, and all-cause mortality.

Study Setting and Population
We undertook a population-based, matched cohort study of residents of Ontario, Canada, who underwent publicly funded bariatric surgery with RYGB or sleeve gastrectomy from March 1, 2010, to March 31, 2015, and who consented to participate in the Ontario Bariatric Registry. Briefly, the Ontario Bariatric Registry [8][9][10][11][12][13][14][15] has collected real-world data since 2010 on all consenting patients eligible for publicly funded bariatric surgery in Ontario, Canada's most populous province. In Ontario, individuals with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of at least 40 or a BMI of at least 35 with obesity-related comorbid conditions (eg, type 2 diabetes) are eligible for publicly funded RYGB, which is the primary bariatric surgery offered to patients with BMI of less than 60. Sleeve gastrectomy is also publicly reimbursed when RYGB is not possible owing to small-bowel disease and/or adhesions or previous surgery or when sleeve gastrectomy is performed as a planned staged surgery in patients with a BMI of greater than 60 to enable the patient to lose weight. 16 As described elsewhere, 14,15 patient-level records of the Ontario Bariatric Registry were linked with administrative health care records housed at ICES. These data sets were linked using unique encoded identifiers and analyzed at ICES, Toronto, Ontario. ICES is an independent, not-for-profit research institute whose legal status under Ontario's health information privacy law allows it to collect and analyze health care and demographic data

Statistical Analyses
Data were analyzed from from May 5, 2020, to May 20, 2021. As in previous work comparing health care expenditures associated with RYGB vs no surgery in Canada, 15 we matched on a propensity score to create comparable cohorts of patients receiving RYGB vs sleeve gastrectomy. Variables included in the score were age, sex, BMI, year of surgery, geographical location (ie, 14 local health integration networks), census neighborhood income quintile, Ontario Marginalization Index, 18 number of major Aggregated Diagnostic Groups (ADG; derived from the Johns Hopkins ACG System, version 10.0), potentially confounding chronic medical conditions derived from validated administrative data case definitions (eg, chronic kidney disease, coronary artery disease, type 2 diabetes, hypertension, hypercholesterolemia, and mood and anxiety disorders), total health care expenditures in the 5 years preceding the index surgery date, and number of days in the hospital and number of emergency department visits in the 365 days preceding the index date. We implemented greedy nearest-neighbor matching, which matches individuals based on the logit of their propensity score and surgical status (ie, RYGB or sleeve gastrectomy) using a caliper width of 0.2 of the SD. The cohorts were compared before and after 1:1 matching using standardized mean differences, where differences greater than 0.1 are generally considered meaningful. 19  To preserve the matched-pair nature of the data, 21  ). An intention-to-treat approach was used, in that patients remained in the group associated with their index bariatric procedure until such time as they lost health insurance coverage (eg, emigrated), died, or reached the end of the 4-year follow-up period. To comply with ICES privacy requirements, table cells for which fewer than 6 individuals contributed to the data were suppressed.

Determinants of Health Care Expenditures
The results of the multivariable GEE regressions presented in Table 4 confirmed that there was no association between the type of bariatric surgery procedure and 4-year overall health care expenditures. However, sleeve gastrectomy was associated with a 7% increase in 4-year costs for elective hospitalization (rate ratio, 1.07; 95% CI, 1.01-1.14) and a 7% decrease in physician costs (rate  also associated with greater costs (eg, BMI of 50-59 and number of ADGs), but the magnitude of the increase was smaller. Table 4 provides the details of the regression analyses.

Discussion
To our knowledge, this is the first study comparing long-term health care expenditures among patients undergoing RYGB vs sleeve gastrectomy. We found no statistically significant differences in 4-year overall health expenditures between matched cohorts of patients undergoing RYGB and sleeve gastrectomy. However, we found a positive association between sleeve gastrectomy and the 4-year costs associated with elective hospitalizations and a negative association with 4-year physician costs. We identified important patient-level factors associated with health care  expenditures, such as history of chronic kidney disease, coronary artery disease, and mental illness admissions, which need further investigation to better understand the costs and outcomes associated with these groups of patients. Other results indicated that after 4 years, the 2 bariatric procedures did not differ significantly in terms of all-cause mortality and all types of rehospitalizations, but fewer subsequent bariatric procedures and more nonelective readmissions were associated with RYGB.

Strengths and Limitations
Our study has several strengths. First, we had access to all publicly funded bariatric surgical procedures in Ontario and administrative databases accounting for all Ontario publicly funded health care expenditures. Therefore, we were able to compare RYGB and sleeve gastrectomy in terms of both inpatient and outpatient health care expenditures before and after the index procedures. We also used propensity score matching to compare sleeve gastrectomy and RYGB, thus providing a rigorous evaluation of the short-and long-term costs associated with RYGB and sleeve gastrectomy. health care expenditures in the 5 years before the index surgery. To provide further context, we used several multivariable regression models to compare expenditures between RYGB and sleeve gastrectomy in terms of hospitalizations, physician services, and other use of health care services.
Although we separated elective vs nonelective hospitalizations in our analyses, we did not examine the underlying reasons for health care use and associated expenditures (eg, surgical complications vs elective joint replacement, which is now possible owing to weight loss after the bariatric procedure).
This is an important avenue for future research. The results of this study are also based on an early cohort of sleeve gastrectomy performed from 2010 to 2015, and the generalizability of these results to more recent patients or those outside Ontario is unknown. Unfortunately, we did not have access to more recent data from the Ontario Bariatric Registry, which would have allowed us to document the outcomes associated with sleeve gastrectomy performed more recently (eg, during the last 5 years