Conversional bariatric surgery seems to be increasing in incidence in adults under 40

In a large retrospective study using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database, conversional bariatric surgery seems to be increasing in incidence in adults under 40, with notable differences in baseline characteristics of patients undergoing different conversional procedures as well as the reasons for conversion.

The study, carried out by researchers from the University of Alberta, Edmonton, Alberta, Canada, to understand indications for conversional surgery, compare cohorts undergoing conversion to various procedures, and then assess safety profiles of those undergoing conversion after the most common initial procedures, adjustable gastric banding (AGB) and sleeve gastrectomy (SG). The included procedures were those that were converted to SG, Roux-en-Y gastric bypass (RYGB), single anastomosis duodeno-ileal switch with sleeve gastrectomy (SADI-S) or biliopancreatic diversion and duodenal switch (BPD/DS).

“Most patients undergoing conversion have an index AGB or SG. For patients with index AGB, RYGB is associated with an increased complications than SG. For patients with index SG, conversion to RYGB and BPD/DS was associated with increase complications than SADI-S,” the study authors reported.

The primary aim of the study was to compare demographic factors and complication rates of younger adults (under 40) getting converted to another procedure. Secondary objectives included comparing complication rate of patients with conversion procedures for patients with common initial procedures. The two initial procedures assessed were AGB, for which SG and RYGB were compared, and SG, for which RYGB, SADI-S and BPD/DS were compared. For this second analysis, only patients who had a single prior procedure were included.

Outcomes

A total of 13,486 patients were included for analysis. Most patients were converted to RYGB (n=9812, 72.8%), followed by SG (n=2283, 16.9%), BPD (n=842, 6.2%) and SADI (n=549, 4.1%). Baseline characteristics revealed patients who were converted to SG were older (35.5±4.1 vs 34.8±4.3, p<0.001) and patients undergoing conversion to SADI-S and BPD/DS had higher BMI than SG and RYGB (48.1 vs 46.5 vs 45.4 vs 41.5, p<0.001).

Regarding comorbidities, there was an increase in patients being converted to BPD/DS and SADI-S, followed by SG and RYGB. For example, insulin-dependent diabetes mellitus (IDDM) was higher in BPD/DS and SADI-S (9.1 and 8.9%, respectively) compared to SG and RYGB (8.1 vs 6.1%, respectively, p<0.001). For GERD, patients were more likely to undergo RYGB (64.2%) if they had a history of GERD compared to the other procedures (28.1 to 31.4%, p<0.001). The number of conversions increased over the study period from 3,582 to 4,998 from 2020 to 2022, largely driven by increases in patients undergoing conversional RYGB (2,411 to 3,778) and SADI-S (133 to 240).

The most common reasons for conversion were GERD (37.0%), weight gain (33.2%) and inadequate weight loss (19.0%). Conversion secondary to GERD was most common in those converted to RYGB (n=4781, 48.7%). For patients undergoing SG, SADI-S and BPD/DS, the most likely reason for conversion was inadequate weight loss and weight gain. Inadequate weight loss and weight gain was the reason for conversion in 27.4% and 44.6% for those being converted to SG, 39.9% and 49.7% for SADI-S, and 42.0% and 46.1% for BPD/DS. These findings were statistically significant among all reasons for conversion (p<0.001).

For patients with primary AGB (n=3240), most underwent conversion to SG (n=2,027, 62.6%) or RYGB (n=1,112, n=34.3%). Among patients with primary SG (n=9,616), most underwent conversion to RYGB (n=8,474, 88.1%). Of patients with primary RYGB (n=170), patients underwent conversion to BPD/DS (n=74, 43.5%) and SG (n=63, 37.1%).

Regarding serious complications, they were highest (5.1%) in the BPD/DS and RYGB groups (5.3 and 5.9%) vs. SG and SADI-S (2.1 and 2.7%, p<0.001). The rate of individual complications tended to be higher in BPD/DS cohort and less with SG. Complications included anastomotic leak which was highest in BPD/DS and SADI-S (1.3 and 1.1% vs overall 0.6%, p=0.010) and bleed which was highest in the BPD/DS and RYGB groups (1.5 and 1.6% vs overall 1.4%, p<0.001). Re-interventions were higher in non-SG conversions (1.2-2.1%) vs SG conversions (0.6%, p<0.001).

“As prevalence of obesity continues to rise and more people are undergoing metabolic and bariatric surgery earlier in life, the rate of bariatric conversion surgery will also likely rise. Currently no consensus exists about best procedure for conversion, and this study may aid in discussions and future discussions regarding this topic,” the researchers concluded. “As revisional surgery can pose significant technical challenges and can carry vastly differing postoperative effects for patients, creation of consensus and decision-aids can help surgeons, multidisciplinary teams and patients when engaging with such populations.”

The findings were reported in the paper, ‘Bariatric conversional surgery in younger adults ≤40: Who gets converted and comparative risks of conversion to subsequent procedures’, published in SOARD. To access this paper, please click here