Bias against biologics in bariatric surgery: is it justified?

Obesity is a known risk factor for autoimmune disorders. Chronic steroid treatment among these patients poses greater surgical risk, but biological/immunomodulating agents (BIA) have allowed for safer alternatives. The effects of BIA monotherapy on postoperative complications following metabolic/bariatric surgery (MBS) have not been studied. We aimed to evaluate the effects of preoperative BIA use on post-metabolic/bariatric surgery outcomes.

We conducted a retrospective matched-pair cohort study of patients who underwent bariatric surgery between 2012 and 2024. Patients were stratified into two groups: those with autoimmune disorders on BIA monotherapy vs matched controls. Patients were matched by age, BMI, and surgery type (Roux-en-Y gastric bypass [RYGB] vs vertical sleeve gastrectomy [VSG]). Paired T-tests were used to compare continuous variables. McNemar's test was used to compare dichotomous variables.

Thirty patients (15 per group) were included in the study. Sixty percent of patients underwent VSG. Among biologic monotherapy patients, 46.7% had rheumatoid arthritis, and 66.7% of BIA were TNF inhibitors. BIAs were used within 12 months of surgery, stopped 6 weeks prior to surgery, and resumed 6 weeks after surgery. Although there was no difference in preoperative comorbidities, BIA group had a significantly higher ASA status (100% with ASA 3) compared to controls (60.0% with ASA 3, p = 0.03). Postoperatively, there were no differences in wound complications (6.7% BIA vs. 0% control, p = 1.00) or readmissions (0% BIA vs 6.7% control, p = 1.00). There were no anastomotic leaks, VTE, or death in either group. Six-month postoperative weight loss was equal between groups: (50.7 ± 15.4%EWL BIA vs 53.4 $\pm$ 19.8%EWL control, p = 0.89; %TWL (19.7 ± 6.1 [15.1-23.8] vs. 21.2 ± 5.9 [16.9-27.6], p = 0.78).

Despite higher ASA status, patients on BIA did not have increased postoperative complications, and had similar weight loss to control patients after MBS. Our data suggests that when managed appropriately, patients on BIA have similar benefits from MBS without added risk.