Association of Insurance Coverage With Adoption of Sleeve Gastrectomy vs Gastric Bypass for Patients Undergoing Bariatric Surgery

Abstract

IMPORTANCEInstrumental variables can control for selection bias in observational research. However, valid instruments are challenging to identify. OBJECTIVE To evaluate regional variation in sleeve gastrectomy following insurance coverage implementation as an instrumental variable in comparative effectiveness research. DESIGN, SETTING, AND PARTICIPANTS This serial cross-sectional study included adult patients in a national Medicare claims database who underwent sleeve gastrectomy or Roux-en-Y gastric bypass from 2012 to 2017. Data analysis was performed from January to June 2021. EXPOSURES Laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass. MAIN OUTCOMES AND MEASURESThe association of the instrumental variable with treatment (ie, undergoing sleeve gastrectomy), as well as mortality, complications, emergency department visits, hospitalization, reinterventions, and surgical revision. RESULTSA total of 76 077 patients underwent bariatric surgery, of whom 44 367 underwent sleeve gastrectomy (mean [SD] age, 56.9 [11.9] years; 32 559 [73.5%] women) and 31 710 underwent gastric bypass (mean (SD) age, 55.9 (11.8) years; 23 750 [74.9%] women). After insurance coverage initiation, there was substantial regional and temporal variation in adoption of sleeve gastrectomy.Prior-year state-level utilization of sleeve gastrectomy was highly associated with undergoing sleeve gastrectomy (Kleibergen-Paap Wald F statistic, 910.3). All but 2 patient characteristics (race and diagnosis of depression) were well-balanced between the top and bottom quartiles of the instrumental variable. Regarding 1-year outcomes, compared with patients undergoing gastric bypass, patients undergoing sleeve gastrectomy had a lower 1-year risk of mortality (0.

Policy Interventions to Enhance Medical Care for People With Obesity in the United States—Challenges, Opportunities, and Future Directions

“…On the patient side, expanded coverage may eliminate financial barriers in the way of accepting MBS-though the vast majority of Americans have coverage for this form of surgery, in contrast to anti-obesity medications. 56 The Critical Challenge: Dispelling Stigma Expanding access to anti-obesity pharmacotherapies, cognitive behavioral therapy, nutritional therapy, and MBS is a prudent, necessary, and relatively easily implemented policy intervention to augment care for people with obesity. But perhaps the most pervasive and insurmountable barrier to effective care for people with obesity in the United States is deep-seated weight stigma.…”

Potential Bias of Instrumental Variable Analysis in Comparative Effectiveness Research for Bariatric Surgery

“…Howard et al use state variation in bariatric procedure rates in the prior year to project whether a patient seeking care in the study year receives sleeve gastrectomy (vs gastric bypass). Geographical variation in procedure rates is 1 of the 4 most commonly used IVs in comparative effectiveness research, but prior research has shown that this instrument is likely biased by IV-outcome confounders .…”

“…Geographical variation is strongly associated with variables that are correlated with health outcomes, such as race and ethnicity, urban vs rural status, and access to other health interventions . In fact, Howard et al found that Black patients undergoing bariatric procedures were more likely to live in areas with higher sleeve gastrectomy rates (and were therefore assigned to the sleeve gastrectomy treatment group by the IV) than White patients. A 2019 JAMA Surgery study found that Black patients had higher rates of complications and health care utilization following bariatric surgery than White patients, even when controlling for surgery type.…”

“…The authors ask: “Can the effects of national insurance coverage decisions serve as an instrumental variable in comparative effectiveness research?” However, the insurance coverage decision was not the instrumental variable used in this study. Howard et al were not able to measure insurance coverage, and their data suggest that all regions elected to cover sleeve gastrectomy (ie, there was no variability in coverage). Therefore, the variation they used for the instrument stems from regional differences in the adoption of the procedure following coverage, which is likely related to health system, physician, and patient characteristics that are related to outcomes.…”

“…For instance, Black patients are less likely to receive major surgical procedures than White patients in the US, and it is well-established that Black race (which is correlated with social and structural determinants of health, including systemic racism) is associated with higher morbidity and mortality . In JAMA Network Open , Howard and colleagues use instrumental variable (IV) analysis as a method to control for selection bias in the comparative effectiveness of 2 bariatric surgery procedures (laparoscopic sleeve gastrectomy and laparoscopic gastric bypass) among Medicare beneficiaries. But, as the authors note, “although effective in their ability to reduce bias, instrumental variables can be difficult to identify.”…”