Abstract
Background
There is a paucity of data comparing 30-day morbidity and mortality of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one anastomosis gastric bypass (OAGB). This study aimed to compare the 30-day safety of SG, RYGB, and OAGB in propensity score-matched cohorts.
Materials and methods
This analysis utilised data collected from the GENEVA study which was a multicentre observational cohort study of bariatric and metabolic surgery (BMS) in 185 centres across 42 countries between 01/05/2022 and 31/10/2020 during the Coronavirus Disease-2019 (COVID-19) pandemic. 30-day complications were categorised according to the Clavien–Dindo classification. Patients receiving SG, RYGB, or OAGB were propensity-matched according to baseline characteristics and 30-day complications were compared between groups.
Results
In total, 6770 patients (SG 3983; OAGB 702; RYGB 2085) were included in this analysis. Prior to matching, RYGB was associated with highest 30-day complication rate (SG 5.8%; OAGB 7.5%; RYGB 8.0% (p = 0.006)). On multivariate regression modelling, Insulin-dependent type 2 diabetes mellitus and hypercholesterolaemia were associated with increased 30-day complications. Being a non-smoker was associated with reduced complication rates. When compared to SG as a reference category, RYGB, but not OAGB, was associated with an increased rate of 30-day complications. A total of 702 pairs of SG and OAGB were propensity score-matched. The complication rate in the SG group was 7.3% (n = 51) as compared to 7.5% (n = 53) in the OAGB group (p = 0.68). Similarly, 2085 pairs of SG and RYGB were propensity score-matched. The complication rate in the SG group was 6.1% (n = 127) as compared to 7.9% (n = 166) in the RYGB group (p = 0.09). And, 702 pairs of OAGB and RYGB were matched. The complication rate in both groups was the same at 7.5 % (n = 53; p = 0.07).
Conclusions
This global study found no significant difference in the 30-day morbidity and mortality of SG, RYGB, and OAGB in propensity score-matched cohorts.
Subject terms: Obesity, Obesity
Introduction
Sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one anastomosis gastric bypass (OAGB) are the three commonest bariatric procedures worldwide [1]. There is currently no randomised controlled trial (RCT) comparing these three procedures in the scientific literature. There are several RCTs comparing two of these three procedures [2, 3] but they were not powered to evaluate differences in morbidity or mortality.
30-day morbidity and mortality is a recognised outcome measure for the evaluation of surgical safety and has been used in surgical literature for several decades [4]. There are large studies comparing 30-day morbidity and mortality of RYGB and SG. Alizadeh et al. [5] reported from an analysis of Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) data in the United States that RYGB was associated with higher 30-day morbidity (4.4% vs 2.3%; adjusted odds ratio (AOR) 0.53; p < 0.01) and 30-day mortality (0.2% vs 0.1%; AOR 0.58; p = 0.07) in comparison with SG. However, there is no large data in the scientific literature comparing 30-day morbidity and mortality of SG and OAGB or RYGB and OAGB.
Notwithstanding the lack of such large data, these direct database comparisons are often flawed due to significant differences in the baseline population. Propensity score matching is a valid tool for comparing non-randomised populations by matching them for confounding variables [6]. To the best of our knowledge, there is only one published study comparing 30-day morbidity and mortality of SG and RYGB [7]; and one comparing RYGB and OAGB [8] in propensity score-matched populations. Both of these studies emanate from the MBSAQIP database. In their study, Kapur et al. [7] found lower adverse events with SG in comparison with RYGB. However, the study by Docimo et al. [8] comparing the 30-day morbidity of OAGB and RYGB had too few patients to be meaningful. It is probably because the MBSAQIP database is not likely to have large numbers of OAGB, a procedure not endorsed by the American Society for Metabolic and Bariatric Surgery.
Global 30-day outcomes after bariatric surgEry duriNg thE COVID-19 pAndemic (GENEVA) study [9] is a large, multinational, observational study evaluating 30-day morbidity and mortality of bariatric and metabolic surgery (BMS) during the Coronavirus Disease-2019 (COVID-19) pandemic. The global reach of the study, a large number of patients, and significant numbers of OAGB procedures submitted to this study present a unique opportunity to compare 30-day morbidity and mortality of SG, OAGB, and RYGB in propensity score-matched cohorts.
Methods
Study design and population
The GENEVA study is an international, multicentre, observational cohort study of BMS performed between 1/05/2020 and 31/10/2020 [9]. The current study included all consecutive patients who underwent a primary SG or RYGB or OAGB during this period. Detailed methods have been published previously [9–11]. Data collection included patients’ demographics, details of surgery performed, and in-hospital as well as 30-day morbidity and mortality. Complications were categorised using the Clavien–Dindo (CD) Classification system for reporting surgical complications [12].
Statistical methods
Only patients with a complete data entry were included in the analysis. Continuous data were presented as median and interquartile range. Frequencies were used to summarise categorical variables. To examine differences between the three individual procedure types, the Fisher’s exact test was used for categorical variables and Kruskal–Wallis analysis of variance testing for continuous variables.
Propensity score matching was completed in a step-wise fashion. Pairwise propensity matching was performed to robustly assess the quality of matching. Standardized mean difference (SMD) was used statistic to examine the balance of covariate distribution between treatment groups. Patients were matched using the following features: sex, Type 2 diabetes mellitus (T2DM) status (No diabetes; diet controlled; oral hypoglycaemics; insulin therapy), hypertension, hypercholesterolaemia, obstructive sleep apnoea, smoking status, age, and baseline body mass index (BMI).
The patients were matched against individuals that had other surgeries using the “nearest” method which utilises a greedy search to match each sample with their nearest neighbour. The distance was calculated using the Mahalanobis distance, which estimates the distribution closest for each point [13]. This procedure was performed in R (R Core Team 2021) using the Matchlt package [14, 15]. The outcome variable was the presence of a complication at 30-days follow-up.
Multivariate analysis was performed to strengthen the resulting statistics from univariate analysis, correcting the influence of each variable on the outcome measured. Multivariate models were created using all the variables used for propensity score matching plus ethnicity (white ethnicity vs other ethnic groups), presence of any co-morbidity, and other unspecified co-morbidity (other than those listed above). Patients were then analysed using a generalised linear model in R (R Core Team 2021) [14].
Results
A total of 470 surgeons from 179 centres in 42 countries submitted data on 7092 adult patients who underwent primary BMS between 1st May 2020 and 31st October 2020 at the participating centres. Of these, complete 30-day morbidity and mortality data were available for 7084 (99.88%) by the 10th of December 2020.
Basic demographics
Of the 7084 patients, 300 patients underwent other procedures and were excluded. A further 14 patients were excluded due to missing values. Complete data were available for a total of 6,770 patients who underwent a primary SG or RYGB or OAGB (SG n = 3983; RYGB n = 2085, OAGB n = 702). Demographic details for all the patients, who underwent any of these three primary procedures are included in Table 1. There were multiple significant differences in baseline demographics between the three groups as detailed in Table 1. RYGB patients were significantly older than patients in the other two cohorts while patients receiving OAGB were more likely to suffer from co-morbidities (Table 1). Patients undergoing SG had the lowest rate of each of these co-morbidities as detailed in Table 1.
Table 1.
Baseline demographics of all patients undergoing a primary SG or RYGB or OAGB (unmatched cohort—14 patients excluded due to incomplete data).
| Characteristic | SG (n = 3983) | OAGB (n = 702) | RYGB (n = 2085) | p value |
|---|---|---|---|---|
| Median Age (years) | 38 (29.2–47.0) | 40 (33.0–50.0) | 43 (34–52) | <0.001a |
| Median BMI (kg/m2) | 41.91 (38.14–46.77) | 43.11 (38.87–48.77) | 41.87 (38.67–45.73) | <0.001a |
| Sex (Female) | 2883 (72%) | 496 (71%) | 1589 (76%) | <0.001b |
| Non-Smoker | 2906 (73%) | 528 (75%) | 1502 (72%) | 0.24b |
| T2DM | 649 (16%) | 229 (33%) | 484 (23%) | <0.001b |
| Diet controlled | 204 (5%) | 74 (11%) | 107 (5%) | |
| Oral hypoglycaemics | 370 (9%) | 106 (15%) | 277 (13%) | |
| Insulin therapy | 75 (2%) | 49 (7%) | 100 (5%) | |
| Hypercholesterolaemia | 763 (19%) | 224 (32%) | 476 (23%) | <0.001b |
| Hypertension | 1101 (28%) | 272 (39%) | 720 (35%) | <0.001b |
| Obstructive sleep apnoea | 975 (24%) | 229 (33%) | 517 (25%) | <0.001b |
SG sleeve gastrectomy, RYGB Roux-en-Y gastric bypass, OAGB one anastomosis gastric bypass, BMI body mass index, T2DM Type 2 diabetes mellitus.
aKruskal–Wallis test.
bFisher’s exact test.
30-day morbidity and mortality in the full cohort (unmatched; Table 2)
Table 2.
Complications according to primary procedure and CD (Clavien–Dindo) classification system in the full unmatched cohort.
| Characteristic | SG (n = 3983) | OAGB (n = 702) | RYGB (n = 2085) | p value |
|---|---|---|---|---|
| All 30-day complications | 233 (5.8%) | 53 (7.5%) | 166 (8.0%) | 0.006a |
| CD 0 | 3750 (94.1%) | 649 (92.4%) | 1919 (92.0%) | – |
| CD 1 | 84 (2.1%) | 11 (1.6%) | 62 (3.0%) | – |
| CD 2 | 63 (1.6%) | 17 (2.4%) | 48 (2.3%) | – |
| CD 3.1 | 16 (0.4%) | 7 (1.0%) | 8 (0.4%) | – |
| CD 3.2 | 50 (1.3%) | 12 (1.7%) | 31 (1.5%) | – |
| CD 4.1 | 13 (0.3%) | 3 (0.4%) | 15 (0.7%) | – |
| CD 4.2 | 3 (0.1%) | 0 | 2 (0.1%) | – |
| CD 5 (Mortality) | 4 (0.1%) | 3 (0.4%) | 0 | 0.016a |
CD Clavien–Dindo, SG sleeve gastrectomy, OAGB one anastomosis gastric bypass, RYGB Roux-en-Y gastric bypass.
aFisher’s exact test.
The overall complication rate was 6.7% (452/6770) (Table 2). RYGB patients had the highest rate of any complication during the 30-day follow-up (8.0% with RYGB vs 7.5% for OAGB and 5.8% for SG (p = 0.006)). There were seven post-operative mortalities (0.1%) (4 with SG, 3 with OAGB, and nil with RYGB; p = 0.016; Fisher’s exact test).
Multivariate analysis of unmatched cohort (Table 3)
Table 3.
Results of multivariate logistic regression on full unmatched cohort.
| Variable | Unmatched patients | |
|---|---|---|
| Odds ratio | 95% CI | |
| Age | 1.000 | 1.000–1.001 |
| BMI | 1.000 | 0.999–1.001 |
| Sex (Male) | 1.011 | 0.997–1.025 |
| Diabetes (No) | 1.010 | 0.984–1.037 |
| Diabetes (oral hypoglycaemics) | 0.981 | 0.961–1.000 |
| Diabetes (insulin) | 1.047* | 1.011–1.083 |
| Hypertension | 1.007 | 0.992–1.022 |
| Hypercholesterolaemia | 1.024* | 1.009–1.040 |
| Obstructive Sleep Apnoea | 1.012 | 0.998–1.027 |
| Non-Smoker | 0.984* | 0.971–0.998 |
| White ethnicity | 1.010 | 0.996–1.025 |
| Other co-morbidity | 1.004 | 0.991–1.017 |
| Surgery (OAGB) | 1.009 | 0.989–1.030 |
| Surgery (RYGB) | 1.018* | 1.005–1.032 |
BMI body mass index, OAGB one anastomosis gastric bypass, RYGB Roux-en-Y gastric bypass, CI confidence interval.
*Significant values where p < 0.05.
On multivariate regression modelling, insulin-dependent T2DM (OR 1.047; 95% CI 1.011–1.083), and hypercholesterolaemia (OR 1.024; 95% CI 1.009–1.040) (Table 3 and Fig. 1) were associated with increased 30-day complications. Being a non-smoker was associated with reduced complication rates (OR 0.984; 95% CI 0.971–0.998). When compared to SG as the reference category, RYGB, but not OAGB, was associated with an increased rate of 30-day complications (OR 1.018; 95% CI 1.005–1.032 for RYGB and OR 1.009; 95% CI 0.989–1.030 for OAGB).
Fig. 1.
Multivariate regression results prior to patient matching.
30-day morbidity and mortality in the propensity score-matched cohort (Tables 4–6)
Table 4.
A comparison of sleeve gastrectomy (SG) and one anastomosis gastric bypass (OAGB) before and after propensity score matching.
| Characteristic | SG (702) | OAGB (702) | Standardised difference pre-matching (95% CI) | Standardised difference post-matching (95% CI) |
|---|---|---|---|---|
| Median Age (years) | 40 (33–49) | 40 (33–50) | 0.203 (0.122–0.283) | 0.011 (−0.093–0.116) |
| Median BMI (kg/m2) | 42.87 (38.79–48.45) | 43.11 (38.87–48.77) | 0.132 (0.052–0.212) | 0.017 (–0.087–0.122) |
| Sex (Female) | 501 (71%) | 496 (71%) | 0.038 (−0.042–0.119) | 0.016 (−0.089–0.12) |
| Non-Smoker | 527 (75%) | 528 (75%) | 0.051 (−0.029–0.132) | 0.003 (−0.101–0.108) |
| T2DM | 229 (33%) | 229 (33%) | 0.407 (0.326–0.488) | 0 (−0.105–0.105) |
| Diet controlled | 74 (11%) | 74 (11%) | ||
| Oral hypoglycaemics | 106 (15%) | 106 (15%) | ||
| Insulin therapy | 49 (7%) | 49 (7%) | ||
| Hypercholesterolaemia | 224 (32%) | 224 (32%) | 0.296 (0.215–0.376) | 0 (−0.105–0.105) |
| Hypertension | 270 (38%) | 272 (39%) | 0.237 (0.157–0.318) | 0.006 (−0.099–0.11) |
| Obstructive sleep apnoea | 230 (33%) | 229 (33%) | 0.181 (0.101–0.261) | 0.003 (−0.102–0.108) |
SG sleeve gastrectomy, OAGB one anastomsis gastric bypass, T2DM Type 2 diabetes mellitus, CI confidence interval.
Table 6.
A comparison of one anastomosis gastric bypass (OAGB) and Roux-en-Y gastric bypass (RYGB) before and after propensity score matching.
| SG (n = 702) | OAGB (n = 702) | p valuea | SG (2085) | RYGB (2085) | p valuea | |
|---|---|---|---|---|---|---|
| 30-day complication | 51 (7.3%) | 53 (7.5%) | 0.68 | 127 (6.1%) | 166 (7.9%) | 0.09 |
| CD 0 | 651 (92.7%) | 649 (92.4%) | 1958 (94%) | 1919 (92%) | ||
| CD 1 | 18 (2.6%) | 11 (1.6%) | 41 (2%) | 62 (3%) | ||
| CD 2 | 10 (1.4%) | 17 (2.4%) | 36 (2%) | 48 (2%) | ||
| CD 3.1 | 7 (1.0%) | 7 (1.0%) | 10 (0%) | 8 (0%) | ||
| CD 3.2 | 10 (1.4%) | 12 (1.7%) | 25 (1%) | 31 (1%) | ||
| CD 4.1 | 3 (0.4%) | 3 (0.4%) | 9 (0%) | 15 (1%) | ||
| CD 4.2 | 1 (0.1%) | 0 | 3 (0%) | 2 (0%) | ||
| CD 5 | 2 (0.3%) | 3 (0.4%) | 3 (0%) | 0 (0%) |
CD Clavien–Dindo, SG sleeve gastrectomy, OAGB one anastomosis gastric bypass, RYGB Roux-en-Y gastric bypass.
aFisher’s exact test.
SG vs OAGB
In total, 702 pairs were matched with a reduction in SMDs for all matched variables (8/8) (Table 4). The overall complication rate in the SG group was 51 (7.3%) as compared to 53 (7.5%) in the OAGB group (Table 7). The difference was not significant (p = 0.68).
Table 7.
Complications in propensity score-matched populations.
| SG (702) | OAGB (702) | p valuea | SG (2085) | RYGB (2085) | p valuea | OAGB (702) | RYGB (702) | p valuea | |
|---|---|---|---|---|---|---|---|---|---|
| 30-day complication | 51 (7.3%) | 53 (7.5%) | 0.68 | 127 (6.1%) | 166 (7.9%) | 0.09 | 53 (7.5%) | 53 (7.5%) | 0.07 |
| CD 0 | 651 (92.7%) | 649 (92.4%) | 1958 (94%) | 1919 (92%) | 649 (92%) | 649 (92%) | |||
| CD 1 | 18 (2.6%) | 11 (1.6%) | 41 (2%) | 62 (3%) | 11 (2%) | 23 (3%) | |||
| CD 2 | 10 (1.4%) | 17 (2.4%) | 36 (2%) | 48 (2%) | 17 (2%) | 10 (1%) | |||
| CD 3.1 | 7 (1.0%) | 7 (1.0%) | 10 (0%) | 8 (0%) | 7 (1%) | 4 (1%) | |||
| CD 3.2 | 10 (1.4%) | 12 (1.7%) | 25 (1%) | 31 (1%) | 12 (2%) | 9 (1%) | |||
| CD 4.1 | 3 (0.4%) | 3 (0.4%) | 9 (0%) | 15 (1%) | 3 (0%) | 7 (1%) | |||
| CD 4.2 | 1 (0.1%) | 0 | 3 (0%) | 2 (0%) | 0 (0%) | 0 (0%) | |||
| CD 5 | 2 (0.3%) | 3 (0.4%) | 3 (0%) | 0 (0%) | 3 (0%) | 0 (0%) |
CD Clavien–Dindo, SG sleeve gastrectomy, OAGB one anastomosis gastric bypass, RYGB Roux-en-Y gastric bypass.
aFisher’s exact test.
SG vs RYGB
In total, 2085 pairs were matched with a reduction in SMDs for seven of the eight matched variables (Table 5). The overall complication rate in the SG group was 127 (6.1%) as compared to 166 (7.9%) in the RYGB group (Table 7). The difference was not significant (p = 0.09).
Table 5.
A comparison of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) before and after propensity score matching.
| Characteristic | SG (2085) | RYGB (2085) | Standardised difference pre-matching (95% CI) | Standardised difference post-matching (95% CI) |
|---|---|---|---|---|
| Median Age (years) | 42.00 (33.00–51.00) | 43.00 (34.00–52.00) | 0.362 (0.309–0.415) | 0.069 (0.008–0.129) |
| Median BMI (kg/m2) | 42.19 (38.70–46.14) | 41.87 (38.67–45.73) | 0.096 (0.043–0.149) | 0.064 (0.003–0.125) |
| Sex (Female) | 1604 (77%) | 1589 (76%) | 0.088 (0.035–0.141) | 0.017 (−0.044–0.078) |
| Non-smoker | 1499 (72%) | 1502 (72%) | 0.021 (−0.032–0.074) | 0.003 (−0.058–0.064) |
| T2DM | 0.215 (0.161–0.268) | 0.06 (−0.001–0.121) | ||
| Diet controlled | 107 (5%) | 107 (5%) | ||
| Oral hypoglycaemics | 277 (13%) | 277 (13%) | ||
| Insulin therapy | 75 (4%) | 100 (5%) | ||
| Hypercholesterolaemia | 477 (23%) | 476 (23%) | 0.09 (0.037–0.143) | 0.001 (−0.06–0.062) |
| Hypertension | 722 (35%) | 720 (35%) | 0.149 (0.096–0.202) | 0.002 (−0.059–0.063) |
| Obstructive sleep apnoea | 543 (26%) | 517 (25%) | 0.007 (−0.046–0.06) | 0.029 (−0.032–0.089) |
CD Clavien–Dindo, SG sleeve gastrectomy, RYGB Roux-en-Y gastric bypass, CI confidence interval, BMI body mass index, T2DM Type 2 diabetes mellitus.
OAGB vs RYGB
In total, 702 pairs were matched with a reduction in SMDs in four of the eight matched variables (4/8) (Table 6). The overall complication rate in both the groups was the same 53 (7.5%; p = 0.07; Table 7).
Discussion
This study shows that there is no significant difference in 30-day morbidity and mortality of SG, RYGB, and OAGB in propensity score-matched cohorts from a large, global dataset collected during the COVID-19 pandemic. Though RYGB was associated with higher 30-day morbidity in comparison with reference SG (OR 1.018; 95% CI 1.005–1.032) in the unmatched cohort on multivariate analysis, the difference disappeared after propensity score matching (p = 0.09). In comparison, OAGB was not associated with higher 30-day morbidity in comparison with SG on either multivariate analysis (OR 1.009; 95% CI 0.989–1.030) or propensity score-matched comparison (p = 0.68).
RCTs comparing different bariatric procedures often have weight loss [2] or diabetes control [16] as their endpoints. Some [16] do not even clearly report 30-day morbidity and mortality with different bariatric procedures let alone classifying surgical complications adequately according to the widely used and accepted CD Classification [12]. We cannot, therefore, derive any scientifically valid conclusions regarding complication rates of different procedures from these RCTs.
Outside of RCTs, perceptions regarding relative safety and efficacy of different procedures for different patient groups may introduce potential bias. For example, in this study, we found 33.0% of patients undergoing OAGB were suffering from T2DM compared to 23.0% undergoing RYGB and 16.0% undergoing SG in the unmatched cohorts. This selection bias may be partly accounted for by fact that the randomised studies have shown superior (non-significant as they were not powered to evaluate these) outcomes in terms of diabetes improvement with OAGB in comparison with RYGB [2] and with RYGB in comparison with SG [17]. This is important because T2DM is known to be associated with complications after bariatric surgery [18, 19] and in our study, Insulin-dependent T2DM was independently associated with 30-day morbidity on multivariate analysis of the unmatched cohort.
Similarly, in the unmatched cohort, hypercholesterolaemia was present in 19.0% of patients undergoing SG in comparison with 32.0% of those undergoing OAGB and 23.0% of those undergoing RYGB. However, after matching, in the analysis of SG and OAGB, the hypercholesterolaemia rates in the two groups were the same at 32.0 and 23.0% in the analysis of SG and RYGB. This is also important because hypercholesterolaemia was independently associated with 30-day morbidity on multivariate analysis of the unmatched data and differences in hypercholesterolaemia rates in the unmatched cohort may well have accounted for some of the observed differences in 30-day morbidity. Others [20] have also found dyslipidaemia to be a predictor of complication after bariatric surgery.
Standardised mean differences in age, BMI, sex, smoking status, hypertension rates all reduced after matching for both the matched comparisons involving SG in this study. Given that all of these characteristics are known to be associated with increased morbidity after bariatric surgery [21–29], differences in these baseline characteristics may have been in part responsible for why the observed difference in morbidity between SG and RYGB or OAGB disappeared after matching. At the same time, and probably because of the fewer number of bypass procedures in the GENEVA database, matching failed to reduce SMDs for age, sex, smoking status, and hypertension in the comparison between OAGB and RYGB in this study. This may partly account for the observed lack of difference in 30-day morbidity between the two procedures. Future studies on this topic need to be mindful of this.
There is no published study comparing the 30-day morbidity of SG with that of OAGB in propensity score-matched cohorts. This may be due to continued reservations [30] amongst some surgeons about OAGB. Furthermore, and as mentioned above in the Introduction section, there is only one propensity score-matched study [8] in the scientific literature comparing the 30-day safety of OAGB with that of any other procedure (RYGB in this case) and that study only had 279 pairs of OAGB and RYGB. One could argue this is not a large enough sample to study differences in morbidity.
There is only one study [7] in the published literature comparing the 30-day morbidity of SG with that of RYGB. Interestingly that study showed lower complication rates with SG in contrast to our findings. It is however worth noting that these authors do not report standardised mean difference in propensity score-matched populations and given the large numbers matched, it was inevitable that their matching was not perfect with significant difference between the matched populations with regards to important confounding variables such as age, BMI, smoking, insulin-dependent T2DM, etc.
This study represents the first large propensity-matched comparison of 30-day morbidity and mortality of SG, RYGB, and OAGB. This data was collected from a large worldwide collaborative study of real-world bariatric surgical practice. Data completion rates were extremely high with 30-day follow data available for 97.9% of patients across the entire cohort and this represents a significant strength of this study.
Non-randomised design and self-reported complication rates are two major weaknesses of this study. However, it is not easy to randomise to different procedures with 30-day morbidity as an endpoint and anonymous data collection strategy used in this study may have diminished the desire to under-report complications. Another weakness of this study is that differences in complication rates, though statistically not significant, maybe clinically relevant. Indeed, larger studies may even find statistical significance.
Conclusion
The present analysis shows that there is no significant difference in 30-day morbidity and mortality of SG, OAGB, and RYGB in propensity-matched cohorts.
Supplementary information
Author contributions
Conceptualisation: RS and KM. Data curation: RS, TW, and JS. Data analysis: VRC, GVG, and CL. Tables and figures: RS, VRC, and CL. Manuscript writing and proof reading: all authors.
Funding
This study is funded by Bariatric Unit, University Hospital Birmingham NHS Foundation Trust.
Competing interests
The authors declare no competing interests.
Footnotes
A full list of author affiliations appears at the end of the paper.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
These authors contributed equally: Rishi Singhal, Victor Roth Cardoso, Tom Wiggins.
Contributor Information
Rishi Singhal, Email: singhal_rishi@hotmail.com.
GENEVA Collaborators:
Michał Pędziwiatr, Piotr Major, Piotr Zarzycki, Athanasios Pantelis, Dimitris P. Lapatsanis, Georgios Stravodimos, Chris Matthys, Marc Focquet, Wouter Vleeschouwers, Antonio G. Spaventa, Carlos Zerrweck, Antonio Vitiello, Giovanna Berardi, Mario Musella, Alberto Sanchez-Meza, Felipe J. Cantu, Jr, Fernando Mora, Marco A. Cantu, Abhishek Katakwar, D. Nageshwar Reddy, Haitham Elmaleh, Mohammad Hassan, Abdelrahman Elghandour, Mohey Elbanna, Ahmed Osman, Athar Khan, Laurent layani, Nalini Kiran, Andrey Velikorechin, Maria Solovyeva, Hamid Melali, Shahab Shahabi, Ashish Agrawal, Apoorv Shrivastava, Ankur Sharma, Bhavya Narwaria, Mahendra Narwaria, Asnat Raziel, Nasser Sakran, Sergio Susmallian, Levent Karagöz, Murat Akbaba, Salih Zeki Pişkin, Ahmet Ziya Balta, Zafer Senol, Emilio Manno, Michele Giuseppe Iovino, Ahmed Osman, Mohamed Qassem, Sebastián Arana-Garza, Heitor P. Povoas, Marcos Leão Vilas-Boas, David Naumann, Alan Li, Basil J. Ammori, Hany Balamoun, Mohammed Salman, Amrit Manik Nasta, Ramen Goel, Hugo Sánchez-Aguilar, Miguel F. Herrera, Adel Abou-mrad, Lucie Cloix, Guilherme Silva Mazzini, Leonardo Kristem, Andre Lazaro, Jose Campos, Joaquín Bernardo, Jesús González, Carlos Trindade, Octávio Viveiros, Rui Ribeiro, David Goitein, David Hazzan, Lior Segev, Tamar Beck, Hernán Reyes, Jerónimo Monterrubio, Paulina García, Marine Benois, Radwan Kassir, Alessandro Contine, Moustafa Elshafei, Sueleyman Aktas, Sylvia Weiner, Till Heidsieck, Luis Level, Silvia Pinango, Patricia Martinez Ortega, Rafael Moncada, Victor Valenti, Ivan Vlahović, Zdenko Boras, Arnaud Liagre, Francesco Martini, Gildas Juglard, Manish Motwani, Sukhvinder Singh Saggu, Hazem Al Momani, Luis Adolfo Aceves López, María Angelina Contreras Cortez, Rodrigo Aceves Zavala, Christine D’Haese RN, Ivo Kempeneers, Jacques Himpens, Andrea Lazzati, Luca Paolino, Sarah Bathaei, Abdulkadir Bedirli, Aydın Yavuz, Çağr Büyükkasap, Safa Özaydın, Andrzej Kwiatkowski, Katarzyna Bartosiak, Maciej Walędziak, Antonella Santonicola, Luigi Angrisani, Paola Iovino, Rossella Palma, Angelo Iossa, Cristian Eugeniu Boru, Francesco De Angelis, Gianfranco Silecchia, Abdulzahra Hussain, Srivinasan Balchandra, Izaskun Balciscueta Coltell, Javier Lorenzo Pérez, Ashok Bohra, Altaf K. Awan, Brijesh Madhok, Paul C. Leeder, Sherif Awad, Waleed Al-Khyatt, Ashraf Shoma, Hosam Elghadban, Sameh Ghareeb, Bryan Mathews, Marina Kurian, Andreas Larentzakis, Gavriella Zoi Vrakopoulou, Konstantinos Albanopoulos, Ahemt Bozdag, Azmi Lale, Cuneyt Kirkil, Mursid Dincer, Ahmad Bashir, Ashraf Haddad, Leen Abu Hijleh, Bruno Zilberstein, Danilo Dallago de Marchi, Willy Petrini Souza, Carl Magnus Brodén, Hjörtur Gislason, Kamran Shah, Antonio Ambrosi, Giovanna Pavone, Nicola Tartaglia, S. Lakshmi Kumari Kona, K. 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Supplementary information
The online version contains supplementary material available at 10.1038/s41366-021-01048-1.
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