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. 2021 Oct 6;156(12):1160–1169. doi: 10.1001/jamasurg.2021.4981

Comparative Safety of Sleeve Gastrectomy and Gastric Bypass Up to 5 Years After Surgery in Patients With Severe Obesity

Ryan Howard 1,2,✉, Grace F Chao 3,4,5, Jie Yang 2, Jyothi Thumma 2, Karan Chhabra 2,3,6, David E Arterburn 7, Andrew Ryan 2,8,9, Dana A Telem 1,2,10, Justin B Dimick 1,2,10
PMCID: PMC8495604  PMID: 34613354

Key Points

Question

What is the long-term comparative safety of sleeve gastrectomy vs gastric bypass?

Findings

This cohort study of a national sample of 95 405 Medicare beneficiaries found that sleeve gastrectomy was associated with a lower risk of mortality, complications, and overall reintervention 5 years after surgery. However, the risk of surgical revision was higher among patients undergoing sleeve gastrectomy.

Meaning

Results suggest that the safety benefits of sleeve gastrectomy persist up to 5 years after surgery; this information may help patients and surgeons make informed treatment decisions.

This cohort study investigates the safety of sleeve gastrectomy vs gastric bypass up to 5 years after surgery in patients with severe obesity.

Abstract

Importance

Sleeve gastrectomy is the most widely used bariatric operation; however, its long-term safety is largely unknown.

Objective

To compare the risk of mortality, complications, reintervention, and health care use 5 years after sleeve gastrectomy and gastric bypass.

Design, Setting, and Participants

This retrospective cohort study included adult patients in a national Medicare claims database who underwent sleeve gastrectomy or gastric bypass from January 1, 2012, to December 31, 2018. Instrumental variables survival analysis was used to estimate the cumulative incidence of outcomes up to 5 years after surgery.

Exposures

Laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass.

Main Outcomes and Measures

The main outcome was risk of mortality, complications, and reinterventions up to 5 years after surgery. Secondary outcomes were health care use after surgery, including hospitalization, emergency department (ED) use, and total spending.

Results

Of 95 405 patients undergoing bariatric surgery, 57 003 (60%) underwent sleeve gastrectomy (mean [SD] age, 57.1 [11.8] years), of whom 42 299 (74.2%) were women; 124 (0.2%) were Asian; 10 101 (17.7%), Black; 1951 (3.4%), Hispanic; 314 (0.6%), North American Native; 43 194 (75.8%), White; 534 (0.9%), of other race or ethnicity; and 785 (1.4%), of unknown race or ethnicity. A total of 38 402 patients (40%) underwent gastric bypass (mean [SD] age, 55.9 [11.7] years), of whom 29 050 (75.7%) were women; 109 (0.3%), Asian; 6038 (15.7%), Black; 1215 (3.2%), Hispanic; 278 (0.7%), North American Native; 29 986 (78.1%), White; 373 (1.0%), of other race or ethnicity; and 404 (1.1%), of unknown race or ethnicity. Compared with patients undergoing gastric bypass, at 5 years after surgery, patients undergoing sleeve gastrectomy had a lower cumulative incidence of mortality (4.27%; 95% CI, 4.25%-4.30% vs 5.67%; 95% CI, 5.63%-5.69%), complications (22.10%; 95% CI, 22.06%-22.13% vs 29.03%; 95% CI, 28.99%-29.08%), and reintervention (25.23%; 95% CI, 25.19%-25.27% vs 33.57%; 95% CI, 33.52%-33.63%). Conversely, patients undergoing sleeve gastrectomy had a higher cumulative incidence of surgical revision at 5 years (2.91%; 95% CI, 2.90%-2.93% vs 1.46%; 95% CI, 1.45%-1.47%). The adjusted hazard ratio (aHR) of all-cause hospitalization and ED use was lower for patients undergoing sleeve gastrectomy at 1 year (hospitalization, aHR, 0.83; 95% CI, 0.80-0.86; ED use, aHR, 0.87; 95% CI, 0.84-0.90) and 3 years (hospitalization, aHR, 0.94; 95% CI, 0.90-0.98; ED use, aHR, 0.93; 95% CI, 0.90-0.97) after surgery but similar between groups at 5 years (hospitalization, aHR, 0.99; 95% CI, 0.94-1.04; ED use, aHR, 0.97; 95% CI, 0.92-1.01). Total health care spending among patients undergoing sleeve gastrectomy was lower at 1 year after surgery ($28 706; 95% CI, $27 866-$29 545 vs $30 663; 95% CI, $29 739-$31 587), but similar between groups at 3 ($57 411; 95% CI, $55 239-$59 584 vs $58 581; 95% CI, $56 551-$60 611) and 5 years ($86 584; 95% CI, $80 183-$92 984 vs $85 762; 95% CI, $82 600-$88 924).

Conclusions and Relevance

In a large cohort of patients undergoing bariatric surgery, sleeve gastrectomy was associated with a lower long-term risk of mortality, complications, and reinterventions but a higher long-term risk of surgical revision. Understanding the comparative safety of these operations may better inform patients and surgeons in their decision-making.

Introduction

Sleeve gastrectomy is the most common bariatric procedure performed in the US.1,2 Composing less than 10% of bariatric procedures in 2010, it now accounts for over 60% of all bariatric procedures.3 Its popularity is owed largely to its excellent short-term safety profile, efficacious weight loss and comorbidity resolution, and technical ease compared with gastric bypass, which is the second most common bariatric operation.4,5,6,7,8 Sleeve gastrectomy is also recognized as a safe surgical option for high-risk patient groups, such as older patients with multiple comorbidities.9,10 Together, sleeve gastrectomy and gastric bypass represent the 2 most frequently performed bariatric operations.11

Although its short-term safety and long-term weight loss efficacy are well described, less is known regarding the long-term safety of sleeve gastrectomy compared with gastric bypass. Although existing randomized clinical trials have followed patients long term, they are limited by a small sample size and may be underpowered to detect differences in rare outcomes.5,6,8,12 For example, the Laparoscopic Gastric Bypass Vs Sleeve Gastrectomy to Treat Morbid Obesity (SLEEVEPASS) and Swiss Multicenter Bypass of Sleeve Study (SM-BOSS) trials did not demonstrate a significant difference in mortality, reoperation, or reintervention between these 2 procedures at 5 years after surgery.8,13 Recent observational studies have been able to analyze larger samples of patients using national registries and claims data; however, they are subject to unmeasured confounding and selection bias given their observational design.14,15 A novel approach to mitigating this limitation is to use an instrumental variables analysis, which uses an exogenous factor affecting treatment choice, but not outcome, to control for potential confounding.16 Although recent studies have used this approach to demonstrate the superior short-term safety of sleeve gastrectomy, whether these early trends persist in the long term is unclear.17,18 Additionally, even less is known about the long-term safety of bariatric procedures in the Medicare population, where obesity and its related diseases affect more than one-third of individuals.19 Although the Centers for Medicare & Medicaid Services now cover both sleeve gastrectomy and gastric bypass for Medicare beneficiaries, no study to date has evaluated the long-term comparative safety of these procedures in this population. As a result, the Medicare Evidence Development and Coverage Advisory Committee has expressed low confidence in existing evidence for bariatric surgery in older patients and those with disabilities and has highlighted the need for more data regarding patient outcomes.20

Therefore, we conducted the following study to describe 5-year outcomes in a large cohort of Medicare beneficiaries undergoing sleeve gastrectomy and gastric bypass. The Medicare data set provides large-scale, nationally representative information about a patient population in which bariatric surgery outcomes are understudied. We used an instrumental variables approach with state-level variation in sleeve gastrectomy as our instrumental variable. We hypothesized that extending this approach to a large, diverse cohort of patients 5 years after surgery could offer an informative, real-world comparison of the long-term safety of these 2 procedures.

Methods

Data Source and Study Population

In this cohort study, we used 100% fee-for-service Medicare claims (Part A, Part B, outpatient, and home health agency) for patients undergoing laparoscopic sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass from January 1, 2012, to December 31, 2018. Eligible patients were identified using Current Procedural Terminology codes 43775, 43644, and 43645, previously described International Classification of Diseases, Ninth Revision (ICD-9) and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) procedure codes, and matching diagnosis codes for severe obesity.17 Although patients with kidney failure were included in the study cohort, patients were excluded if their Medicare entitlement was specifically attributable to end-stage kidney disease, given that these patients represent a subpopulation with significantly higher mortality, morbidity, and health care spending.18,21,22 Patients were also excluded if they had a diagnosis code associated with gastric or small-bowel cancer. For clinical outcomes, patients were excluded if they did not have 3-month continuous enrollment before their index admission. For health care spending outcomes, patients were included if they had 3-month continuous enrollment before their index admission as well as continuous enrollment for 1, 3, or 5 years after surgery. Participant race and ethnicity were included in the Medicare claims database used for this study, and therefore, those identifiers were used to identify participant race and ethnicity. We chose to include these data because bariatric surgery outcomes have been demonstrated to differ by race and ethnicity. Race and ethnicity comprised the following patient categories: Asian, Black, Hispanic, North American Native, White, other, and unknown. As a secondary analysis of deidentified administrative claims data, this study was determined to be exempt from regulation and the need for patient consent by the University of Michigan institutional review board. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

Primary Outcomes

The primary outcomes of interest were the cumulative incidence of mortality, complications, and reinterventions up to 5 years after surgery. Clinically significant complications associated with bariatric surgery were defined using ICD-9 and ICD-10 diagnosis and procedure codes based on previously published work (eTables 3 and 4 in the Supplement).23 Complication categories included splenic, hemorrhagic, anastomotic, wound-related, obstruction-related, pulmonary, cardiac, neurologic, genitourinary, thromboembolic, shock, and unexpected reoperations.

Reinterventions were defined based on prior work in order to meaningfully compare our results with those previously published (eTable 2 in the Supplement).14,15,24 Reinterventions were grouped into 5 categories: revision, reoperation, enteral access, vascular access, and other interventions.

Revisions included any operation that involved modifying the index bariatric procedure, such as conversion to another bariatric procedure (eg, conversion of sleeve gastrectomy to gastric bypass), gastrectomy, or anastomotic revision. Reoperations included any abdominal operation potentially related to the index bariatric procedure, but not directly affecting bariatric physiology, such as abdominal wall hernia repair, biliary procedures, internal hernia repair, and paraesophageal hernia repair. Reoperations within the first 30 days of the index bariatric procedure were excluded, as these may represent delayed claims for procedures performed with the index operations.17 For example, when a ventral hernia repair is performed concurrently with the index operation, the claim for that additional procedure may appear at a later date, resulting in overestimation of early reoperation.24 Enteral access included any surgical, endoscopic, or interventional enteral access procedures. Vascular access included any vascular access procedures to reflect the need for parenteral nutrition. Other interventions included any other interventional procedures, such as drainages, aspiration, diagnostic laparoscopy, etc.

Secondary Outcomes

The secondary outcome of interest was health care use in the 5 years after surgery, represented as all-cause emergency department (ED) use, all-cause hospitalization, and health care expenditures. Emergency department use was identified using a revenue center code algorithm previously described by the Research Data Assistance Center.14 Emergency department use resulting in hospital admission was categorized as hospitalization only. Health care expenditures were calculated at 1, 3, and 5 years using cumulative Medicare spending after and including the index operation, excluding non-Medicare expenditures. Price standardization was performed to 2018 US dollars, adjusting for intentional Medicare price differences for the same services.25,26,27,28

Statistical Analysis

Analytic Approach Overview

Descriptive statistics were calculated for patient demographic information including age, sex, and race, as well as year of operation and patient comorbidities. Univariate statistics were calculated using the χ2 test or t test as appropriate to compare baseline differences between the 2 groups. The primary analysis for this study used a Cox proportional hazards model with instrumental variables to estimate the adjusted hazards ratio (aHR) for the outcomes of interest in sleeve gastrectomy compared with gastric bypass. The use of instrumental variables in survival analysis has been previously described as a novel way to control for unmeasured confounding.29,30 The model included all variables from Table 1 as covariates (ie, age, sex, race, year, and all comorbidities), as these factors have been shown to be significantly associated with outcomes after bariatric surgery.17,18,31,32,33 Patients were censored if they disenrolled from Medicare or reached the end of the study period. Outcomes were treated independently, and competing-risk regression models were not used.

Table 1. Cohort Characteristics.
Characteristic No. (%)
Gastric bypass (n = 38 402) Sleeve gastrectomy (n = 57 003)
Age, mean (SD), y 55.9 (11.7) 57.1 (11.8)
Women 29 050 (75.7) 42 299 (74.2)
Men 9352 (24.4) 14 704 (25.8)
Race
Asian 109 (0.3) 124 (0.2)
Black 6038 (15.7) 10 101 (17.7)
North American Native 278 (0.7) 314 (0.6)
White 29 986 (78.1) 43 194 (75.8)
Other 373 (1.0) 534 (0.9)
Unknown 404 (1.1) 785 (1.4)
Ethnicity
Hispanic 1215 (3.2) 1951 (3.4)
Year of operation
2012 8417 (21.9) 519 (0.9)
2013 6593 (17.2) 6727 (11.8)
2014 5672 (14.8) 8904 (15.6)
2015 5100 (13.3) 10 102 (17.7)
2016 4493 (11.7) 10 407 (18.3)
2017 4267 (11.1) 10 831 (19.0)
2018 3861 (10.1) 9513 (16.7)
Comorbidities
Hypertension 29 513 (76.9) 43 253 (75.9)
Diabetes without chronic complications 17 094 (44.5) 20 745 (36.4)
Depression 11 562 (30.1) 14 861 (26.1)
Chronic pulmonary disease 10 914 (28.4) 15 062 (26.4)
Hypothyroidism 6895 (18.0) 10 364 (18.2)
Liver disease 5691 (14.8) 7424 (13.0)
Diabetes with chronic complications 4182 (10.9) 5212 (9.1)
Psychoses 3013 (7.9) 3619 (6.4)
Deficiency anemias 2435 (6.3) 3293 (5.8)
Fluid and electrolyte disorders 2395 (6.2) 2923 (5.1)
Congestive heart failure 2338 (6.1) 3736 (6.6)
Kidney failure 2308 (6.0) 3428 (6.0)
Other neurologic disorders 2145 (5.6) 3114 (5.5)
Rheumatoid arthritis/collagen vascular disease 1495 (3.9) 2596 (4.6)
Peripheral vascular disease 698 (1.8) 919 (1.6)
Pulmonary circulation disease 477 (1.2) 409 (0.7)
Valvular disease 683 (1.8) 1113 (2.0)
Coagulopathy 354 (0.9) 497 (0.9)
Weight loss 162 (0.4) 140 (0.3)
Paralysis 195 (0.5) 337 (0.6)
Solid tumor without metastasis 93 (0.2) 162 (0.3)
Chronic blood loss anemia 76 (0.2) 69 (0.1)
Lymphoma 39 (0.1) 76 (0.1)
AIDS 43 (0.1) 85 (0.2)
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Initial analysis using Schoenfeld residuals testing revealed that several outcome variables violated the proportional hazards assumption in the Cox regression. This assumption states that the effect of a treatment does not change over time and therefore has a single HR for the duration of the study period.34 Therefore, we included an interaction term with time for covariates in the model that were nonproportional as well as the treatment variable in order to present the aHRs for primary and secondary outcomes at 1, 3, and 5 years after surgery.35 Estimates from the Cox proportional hazards models with covariates set to their mean value were used to calculate the adjusted cumulative incidence of each outcome.15

In addition to evaluating outcomes in the overall cohort, we also stratified the study cohort by Medicare entitlement due to those aged 65 years or older and entitlement due to disability, as prior work has shown that outcomes differ between these 2 groups.18 For these groups, the aHRs at 1, 3, and 5 years were calculated as described previously.

Instrumental Variable Assumptions and Modeling

The instrumental variable for this analysis was state-level sleeve gastrectomy use relative to gastric bypass in the prior year. In order to be valid, an instrument must (1) be highly associated with selection of treatment and (2) affect outcomes of interest only through treatment choice rather than through any other clinical or contextual factors.36 A complete description of the validity and balance of these instrumental variables is available in the eMethods, eFigure, and eTables 1 and 2 in the Supplement. In brief, we found a very strong association of prior year use rate with treatment, as reflected by an F statistic of 910.22. The minimum F statistic of a strong instrument is generally accepted as 10.37 Second, lagged local treatment patterns reflect patient comorbidities and care decisions from a previous time period and are unrelated to current outcomes. Moreover, the validity of this instrument in bariatric surgery comparative effectiveness has been demonstrated in previously published research.17,18

The instrumental variables–adjusted analysis additionally controlled for all variables in Table 1. All multivariable regression analyses accounted for clustering at the state level, as this was the level at which Medicare Local Coverage Determinations went into effect. All statistical tests were performed using SAS, version 9.4 (SAS Institute Inc) and Stata, version 15.1 (StataCorp LLC). Tests were 2-sided, and significance was set at P < .05. Correction for multiple outcomes was not performed, in keeping with our previously reported shorter-term outcomes.17,18 Robust SEs were used to account for state-level heteroscedasticity.

Results

We identified 95 405 Medicare patients who underwent bariatric surgery between January 1, 2012, and December 31, 2018, of whom 57 003 (60%) underwent sleeve gastrectomy and 38 402 (40%) underwent gastric bypass. Patients who underwent sleeve gastrectomy had a mean (SD) age of 57.1 (11.8) years and included 42 299 women (74.2%), 124 Asian patients (0.2%), 10 101 Black patients (17.7%), 1951 Hispanic patients (3.4%), 314 North American Native patients (0.6%), 43 194 White patients (75.8%), 534 patients who identified as other (0.9%), and 785 patients of unknown race or ethnicity (1.4%). Patients who underwent gastric bypass had a mean (SD) age of 55.9 (11.7) years and included 29 050 women (75.7%), 109 Asian patients (0.3%), 6038 Black patients (15.7%), 1215 Hispanic patients (3.2%), 278 North American Native patients (0.7%), 29 986 White patients (78.1%), 373 patients who identified as other (1.0%), and 404 patients of unknown race or ethnicity (1.1%). The share of sleeve gastrectomy during the study period rose from 5.8% (519 of 8936) in 2012 to 71.1% (9513 of 13 374) in 2018. Full demographic characteristics and comorbidities are displayed in Table 1. Median time to follow-up for primary outcomes in this study was 479 days (IQR, 185-942 days) for sleeve gastrectomy and 496 days (IQR, 165-1107 days) for gastric bypass.

We present the aHRs for outcomes after sleeve gastrectomy compared with gastric bypass in Table 2 (unadjusted results are presented in eTable 5 in the Supplement). Mortality was less likely after sleeve gastrectomy than gastric bypass at 1, 3, and 5 years, which corresponds to a cumulative incidence of mortality of 1.13% for sleeve gastrectomy (95% CI, 1.12%-1.13%) vs 1.50% for gastric bypass (95% CI, 1.50%-1.51%) at 1 year, 2.61% (95% CI, 2.60%-2.62%) vs 3.47% (95% CI, 3.46%-3.49%) at 3 years, and 4.27% (95% CI, 4.25%-4.30%) vs 5.67% (95% CI, 5.63%-5.69%) at 5 years (Figure 1A). Complications were also less likely after sleeve gastrectomy at 1, 3, and 5 years, corresponding to a cumulative incidence of complications of 10.95% (95% CI, 10.93%-10.96%) vs 14.72% (95% CI, 14.71%-14.74%) at 1 year, 17.23% (95% CI, 17.21%-17.25%) vs 22.88% (95% CI, 22.85%-22.90%) at 3 years, and 22.10% (95% CI, 22.06%-22.13%) vs 29.03% (95% CI, 28.99%-29.08%) at 5 years (Figure 1B).

Table 2. Adjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years.

Outcome Adjusted hazard ratio (95% CI)a
1 y 3 y 5 y
Mortality 0.68 (0.61-0.76) 0.78 (0.70-0.88) 0.84 (0.74-0.95)
Complication 0.73 (0.68-0.77) 0.73 (0.67-0.79) 0.73 (0.67-0.80)
Hospitalization 0.83 (0.80-0.86) 0.94 (0.90-0.98) 0.99 (0.94-1.04)
Emergency department use 0.87 (0.84-0.90) 0.93 (0.90-0.97) 0.97 (0.92-1.01)
Reintervention 0.67 (0.63-0.72) 0.74 (0.68-0.80) 0.77 (0.71-0.85)
Revision 1.34 (1.06-1.69) 2.53 (1.89-3.39) 3.41 (2.44-4.74)
Enteral access 0.50 (0.42-0.60) 0.58 (0.46-0.72) 0.62 (0.48-0.80)
Vascular access 0.96 (0.84-1.09) 1.06 (0.88-1.29) 1.12 (0.88-1.41)
Reoperation 0.59 (0.55-0.63) 0.63 (0.58-0.69) 0.66 (0.59-0.73)
Abdominal wall hernia 0.74 (0.66-0.83) 0.87 (0.78-0.98) 0.94 (0.82-1.08)
Biliary 0.61 (0.55-0.67) 0.55 (0.48-0.62) 0.52 (0.45-0.60)
Internal hernia 0.07 (0.04-0.11) 0.05 (0.03-0.09) 0.05 (0.02-0.09)
Paraesophageal hernia 2.47 (1.78-3.41) 2.92 (2.08-4.10) 3.16 (2.16-4.63)
Other 0.38 (0.34-0.42) 0.39 (0.34-0.45) 0.40 (0.34-0.46)
Other intervention 0.88 (0.76-1.01) 0.91 (0.76-1.08) 0.92 (0.76-1.12)
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a

Instrumental variables–adjusted analysis controlling for age, sex, race and ethnicity, year of surgery, and comorbidities in the Cox proportional hazards model. Covariates that violated the proportional hazards assumption were interacted with time.

Figure 1. Cumulative Incidence of Mortality, Complication, All-Cause Hospitalization, and All-Cause Emergency Department Use Comparing Sleeve Gastrectomy and Gastric Bypass.

Figure 1.

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For mortality (A), complication (B), hospitalization (C), and emergency department use (D), complication categories included splenic, hemorrhagic, anastomotic, wound-related, obstruction-related, pulmonary, cardiac, neurologic, genitourinary, thromboembolic, shock, and unexpected reoperations. A list of complications is included in eTable 1 in the Supplement. Estimates from the Cox proportional hazards models with covariates set to their mean value were used to calculate the adjusted cumulative incidence of each outcome.

The adjusted risk of any reintervention was lower after sleeve gastrectomy at 1, 3, and 5 years, corresponding to a cumulative incidence of 7.64% (95% CI, 7.63%-7.65%) vs 10.58% (95% CI, 10.57%-10.59%) at 1 year, 17.88% (95% CI, 17.86%-17.90%) vs 24.20% (95% CI, 24.17%-24.23%) at 3 years, and 25.23% (95% CI, 25.19%-25.27%) vs 33.57% (95% CI, 33.52%-33.63%) at 5 years for sleeve gastrectomy vs gastric bypass (Figure 2A). The adjusted risk of reoperation was also lower after sleeve gastrectomy at 1, 3, and 5 years (Figure 2B). However, sleeve gastrectomy was associated with a higher risk of revision, with an aHR of 3.41 (95% CI, 2.44-4.74) at 5 years. This difference in the cumulative incidence of revision between the 2 groups increased at each time point, from 0.84% (95% CI, 0.84%-0.84%) vs 0.42% (95% CI, 0.42%-0.42%) at 1 year, 2.02% (95% CI, 2.01%-2.02%) vs 1.01% (95% CI, 1.01%-1.02%) at 3 years, and 2.91% (95% CI, 2.90%-2.93%) vs 1.46% (95% CI, 1.45%-1.47%) at 5 years (Figure 2C). Additionally, the risk of paraesophageal hernia repair was higher after sleeve gastrectomy. Enteral access after sleeve gastrectomy was less likely at 1, 3, and 5 years; however, there was no significant difference in the risk of vascular access between the 2 groups (Figure 2D). Results stratified by Medicare entitlement group (disability vs age 65 years or older) are presented in eTables 6-8 in the Supplement. These stratified results generally follow the results of the overall cohort, except that the risk of revision at 5 years was lower among beneficiaries entitled by age (aHR, 1.55; 95% CI, 1.01-2.09 vs aHR, 3.25; 95% CI, 2.51-4.00 for disability entitlement).

Figure 2. Cumulative Incidence of Reintervention, Reoperation, Revision, and Enteral Access Comparing Sleeve Gastrectomy and Gastric Bypass.

Figure 2.

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A, Reinterventions included any of the following categories: revision, reoperation, enteral access, vascular access, and other interventions. B, Reoperations included any abdominal operation potentially related to the index bariatric procedure but not directly affecting bariatric physiology. C, Revisions included any operation that involved modifying the index bariatric procedure. D, Enteral access included any surgical, endoscopic, or interventional enteral access procedures. Estimates from the Cox proportional hazards models with covariates set to their mean value were used to calculate the adjusted cumulative incidence of each outcome.

Regarding postoperative health care use, all-cause hospitalization and ED use were less likely at 1 and 3 years after sleeve gastrectomy, but this difference was not significant at 5 years for either outcome (1-year hospitalization, aHR, 0.83; 95% CI, 0.80-0.86; ED use, aHR, 0.87; 95% CI, 0.84-0.90 and 3-year hospitalization, aHR, 0.94; 95% CI, 0.90-0.98; ED use, aHR, 0.93; 95% CI, 0.90-0.97 vs 5-year hospitalization, aHR, 0.99; 95% CI, 0.94-1.04; ED use, aHR, 0.97; 95% CI, 0.92-1.01) (Figure 1C and 1D). Total health care expenditures were lower after sleeve gastrectomy at 1 year ($28 706; 95% CI, $27 866-$29 545 vs $30 663; 95% CI, $29 739-$31 587), however, there was no significant difference in expenditures at 3 years ($57 411; 95% CI, $55 239-$59 584 vs $58 581; 95% CI, $56 551-$60 611) or at 5 years ($86 584; 95% CI, $80 183-$92 984 vs $85 762; 95% CI, $82 600-$88 924) (Figure 3).

Figure 3. Total Health Care (Medicare) Spending.

Figure 3.

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Total health care spending in 2018 price standardized dollars. Error bars represent 95% CIs.

aIndicates P < .05.

Discussion

In this large, retrospective cohort study of patients undergoing bariatric surgery, sleeve gastrectomy was associated with a lower risk of mortality, complications, reintervention, and other adverse events compared with gastric bypass up to 5 years after surgery. Despite these benefits, the rate of surgical revision at 5 years was higher for patients who underwent sleeve gastrectomy, and total health care spending was equivalent between groups. To our knowledge, this is the first study to describe 5-year outcomes after bariatric surgery in a national population of patients with Medicare, in whom bariatric surgery is becoming increasingly common.38 Overall, these results suggest that previously reported trends in early outcomes were sustained up to 5 years after surgery.

The use of bariatric surgery as a treatment for obesity and obesity-related diseases has increased exponentially in recent decades.1 Although sleeve gastrectomy and gastric bypass have been shown to achieve similar weight loss and comorbidity resolution, trials such as SM-BOSS and SLEEVEPASS were unable to detect a difference in postoperative mortality, morbidity, or reintervention between the 2 procedures.8,13 More recent retrospective, observational studies have benefited from larger sample sizes and have suggested that patients undergoing sleeve gastrectomy may have a lower incidence of reinterventions or reoperations; however, these findings have been marginal and are subject to significant confounding.39,40,41 For example, Courcoulas et al15 performed a large, observational study of 5-year outcomes after these 2 procedures. Their analysis similarly found that the risk of reoperation, reintervention, endoscopy, and hospitalization was lower for patients undergoing sleeve gastrectomy. The need for surgical revision after sleeve gastrectomy, however, has remained a potential disadvantage of this operation. Although their study did demonstrate a trend toward increased risk of revision after sleeve gastrectomy, this result was nonsignificant. Similarly, they found no significant difference in 5-year mortality between the 2 operations.

To our knowledge, this was the first large study to demonstrate a long-term difference in mortality for these 2 procedures: 5 years after surgery, the cumulative incidence of mortality for patients undergoing sleeve gastrectomy was 4.27% compared with 5.67% for patients undergoing gastric bypass. This absolute difference in 5-year mortality of 1.4 percentage points translates to a 32.8% relative difference in mortality between the 2 procedures and a number needed to harm of 71. Consequently, had all patients in the current study undergone sleeve gastrectomy, we can estimate that roughly 540 fewer deaths would have occurred at the 5-year time point. This increased risk of mortality may be driven by the increased incidence of complications after gastric bypass, which is in line with other large observational studies.7 Nevertheless, this mortality difference should also be understood within the context of other potential benefits of bypass, such as superior weight loss and, in the current study, a lower incidence of surgical revision.42,43 This highlights the need for additional long-term studies to better understand the competing risks and benefits of these 2 ubiquitous operations.

Although the current study did not investigate clinical outcomes such as weight loss, comorbidity resolution, and medication discontinuation after surgery, trends in long-term health care spending may offer insight into the comparative effectiveness of these procedures. Despite the differences in long-term outcomes between these procedures, total health care spending was only lower for sleeve gastrectomy in the first postoperative year. Previous studies have also corroborated the cost equivalency of these 2 procedures after the initial postoperative period.18 Insofar as adverse events drive health care spending, one might expect the lower cost of sleeve gastrectomy to be sustained for all 5 years. Therefore, there may be other drivers of health care spending not under examination in the current study that account for this lack of a difference. For example, studies have found that gastric bypass may offer superior weight loss and comorbidity resolution, especially for patients with severe obesity.42,43 Lower health care spending associated with these health benefits may offset the higher spending associated with increased health care use. Alternatively, the increased incidence of surgical revision among patients who underwent sleeve gastrectomy may negate potential savings, especially given the intensive evaluation that often precedes revision.44 This is also consistent with the observation that revision tends to occur 2 to 3 years after surgery, at which point spending equilibrated between procedures.44,45 Although the current study demonstrated long-term economic trends associated with these procedures, future studies are needed to understand the drivers of these trends.

This study builds on 2 previous studies that used instrumental variable methods to investigate short-term outcomes after sleeve gastrectomy and gastric bypass. Chhabra et al17 performed the first instrumental variables analysis of these 2 operations in commercially insured adults and found a similar reduction in complications and reinterventions 2 years after sleeve gastrectomy, but an increased absolute risk of revision. Chao et al18 performed an instrumental variables analysis of 3-year outcomes among Medicare patients stratified by Medicare entitlement (disability vs age 65 years or older). Although complications, health care use, and overall reinterventions were less common after sleeve gastrectomy at 3 years for both groups, mortality was only lower in patients entitled to Medicare through disability. Similarly, that study demonstrated that sleeve gastrectomy had an increased absolute risk of revision at 3 years for disabled Medicare beneficiaries only. In the current study, this trend continued at 5 years after surgery, with a significant increase in risk of revision among disabled Medicare beneficiaries, but only a marginal increase at 5 years among older beneficiaries. Therefore, although the safety benefits of sleeve gastrectomy over gastric bypass may be generalizable to patients of older age, the risk of revision may not be as significant in this population. The current study not only provides longer-term outcomes, but demonstrates how trends in outcomes change over time and among important subgroups.

Strengths and Limitations

This study had some advantages, namely, a large sample size and use of econometric techniques to control for confounding. This study also had some limitations. The use of Medicare claims to construct the study cohort may have limited the generalizability of our findings. Specifically, we observed a higher incidence of complications and other adverse outcomes than has been previously reported.23,46 The larger effect size we observed is likely due to several factors, including longer-term follow-up time relative to previous studies as well as the relative age of the cohort, which was a decade older than in similar studies.15,17 In fact, studies that have continued to monitor patients up to 5 years after surgery, such as the SLEEVEPASS trial, have actually reported similar complication rates to those reported here.13 Moreover, this larger effect size may be due to more complete capture of long-term clinical events, given that Medicare tends to have superior continuous enrollment compared with commercial plans.47 Given the dramatic rise in use of bariatric surgery among patients with Medicare, understanding short-term and long-term outcomes in this population is critical. Conversely, understanding long-term outcomes in younger patients without disability is equally important. Another limitation was the lack of clinical granularity in administrative claims data, as highlighted by our inability to discern drivers of health care spending during the study period. For example, this study did not analyze clinical outcomes such as weight loss and comorbidity resolution, which are crucial to understanding the comparative effectiveness of these 2 procedures and should be the focus of future work. Additionally, use of instrumental variables generates a local average treatment effect for marginal patients, and therefore, these results are less applicable to patients who have a relatively strong indication for one procedure vs the other. Moreover, it should be noted that, similar to other studies that analyze large administrative data sets, this study was likely overpowered to detect differences that, though statistically significant, had little to no clinical significance, and readers should interpret the magnitude and uncertainty of these differences accordingly. Last, despite the use of instrumental variables, this study was limited by its observational, nonrandomized design.

Conclusions

Among this large cohort of Medicare beneficiaries, sleeve gastrectomy was associated with a lower long-term risk of death, complications, and overall reintervention compared with gastric bypass over a 5-year period. This further supports the comparative safety of sleeve gastrectomy vs gastric bypass. However, patients undergoing sleeve gastrectomy were more likely to require surgical revision 5 years after surgery. Longer-term randomized clinical trials and observational studies are warranted to confirm these findings. Understanding the risk profile of various bariatric operations may further help patients and surgeons make the most appropriate decisions regarding plans of care.

Supplement.

eMethods

eFigure. State-Level Sleeve Gastrectomy Utilization Among the 10 Largest States From 2011-2018

eTable 1. Association of Instrument With Treatment

eTable 2. Covariate Balance Grouped by Actual Treatment (Sleeve Gastrectomy vs Gastric Bypass) and Grouped by Top (4th) and Bottom (1st) Quartiles of Prior-Year Sleeve Gastrectomy Utilization (Instrumental Variable)

eReferences

eTable 3. Complication Categories

eTable 4. Reintervention Categories and CPT Codes

eTable 5. Unadjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years

eTable 6. Cohort Characteristics by Disability and Age Entitlement to Medicare

eTable 7. Adjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years Among Disabled Medicare Beneficiaries

eTable 8. Adjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years Among Elderly (Age ≥65 years) Medicare Beneficiaries

Click here for additional data file. (498.8KB, pdf)

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplement.

eMethods

eFigure. State-Level Sleeve Gastrectomy Utilization Among the 10 Largest States From 2011-2018

eTable 1. Association of Instrument With Treatment

eTable 2. Covariate Balance Grouped by Actual Treatment (Sleeve Gastrectomy vs Gastric Bypass) and Grouped by Top (4th) and Bottom (1st) Quartiles of Prior-Year Sleeve Gastrectomy Utilization (Instrumental Variable)

eReferences

eTable 3. Complication Categories

eTable 4. Reintervention Categories and CPT Codes

eTable 5. Unadjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years

eTable 6. Cohort Characteristics by Disability and Age Entitlement to Medicare

eTable 7. Adjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years Among Disabled Medicare Beneficiaries

eTable 8. Adjusted Hazard Ratios for Outcomes of Sleeve Gastrectomy vs Gastric Bypass at 1, 3, and 5 Years Among Elderly (Age ≥65 years) Medicare Beneficiaries

Click here for additional data file. (498.8KB, pdf)

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