Bariatric surgery associated with improved IBD outcomes

Bariatric surgery is associated with improved inflammatory bowel disease (IBD)-related outcomes among patients with inflammatory bowel disease and obesity, according to researchers writing on behalf of the Swedish Inflammatory Bowel Disease Register (SWIBREG) study group. They said the findings suggest a potential benefit from bariatric surgery among patients with concomitant obesity and inflammatory bowel disease.

The study authors noted that both IBD and obesity are increasing and up to 40% of patients with IBD may also have obesity. Bariatric surgery can reduce chronic inflammation and may therefore have an impact on existing IBD. In addition, previous studies have reported improvement in IBD-related symptoms for patients with ulcerative colitis after bariatric surgery, studies on surgery’s effect on patients with Crohn's disease have been contradictory. Furthermore, there have been some reports that surgery results in an increased risk of new incident IBD. Subsequently, concerns around the deterioration of IBD and Crohn's disease has results in some m surgeons believing these diseases are relative contraindications to bariatric surgery.

Therefore, researchers form the SWIBREG study group designed a study that compared IBD-related outcomes between patients with obesity and IBD with and without bariatric surgery (Roux-en-Y gastric bypass or sleeve gastrectomy).

This was a registry-based cohort study based on prospectively collected register data in Sweden. Data was collected form the Total Population Register, the National Patient Register, the Prescribed Drug Register, ESPRESSO (Epidemiology Strengthened by histopathology Reports in Sweden, containing gastrointestinal histopathology data for all pathology registers nationwide), the Swedish IBD register and the Scandinavian Obesity Surgery Registry (SOReg).

The primary outcome was a composite measure of first occurrence of IBD-related hospitalisation (IBD main diagnostic listing) and secondary outcomes were the above components considered separately: first IBD-related hospitalisation; start of systemic corticosteroid use; start of immunomodulatory therapy; start of new therapy with immunomodulator or biological agent; or major IBD-related surgery.

After applying exclusion criteria, 455 patients who underwent bariatric surgery and 2,811 patients with obesity who did not undergo bariatric surgery were available for matching. Patients were matched 1:1 with a two-stage matching process between those undergoing bariatric surgery with those who did not.

The study included 798 patients with inflammatory bowel disease and obesity: 399 who underwent bariatric surgery (145 Crohn's disease, 238 ulcerative colitis, 16 unclassified inflammatory bowel disease) and 399 who did not have surgery. Patients in the surgery group were more often women, younger, with a higher BMI and had more metabolic co-morbidities.

Outcomes

In the surgery group, 191 patients underwent Roux-en-Y gastric bypass (47.9%) and 208 had sleeve gastrectomy (52.1%). Mean absolute weight loss at one year after surgery was 36(10) kg (total weight loss 31(7)%) after RYGB, and 31(11) kg (total weight loss 27(8)%) after SG.

A postoperative complication occurred during the first 30 days after bariatric surgery in 32 patients (8.0%). The most common complication registered was leak or intra-abdominal abscess/infection, which occurred in nine patients (2.3%), followed by bleeding in six (1.5%).

IBD-related outcomes

Over a median observation period of 3.3 years, the composite primary endpoint occurred in 201 patients who had bariatric surgery (50.4%; incidence rate 11.9 (95% c.i. 10.2 to 13.5) per 100 person-years) and 226 patients in the no-surgery group (56.6%; incidence rate 15.1 (13.1 to 17.0) per 100 person-years) (adjusted hazard ratios (HR) 0.66, 95% c.i. 0.51 to 0.85) (Figure 1).

Figure 1: Kaplan–Meier failure curve for time to composite primary outcome. The primary outcome included first occurrence of IBD-related hospitalisation, start of systemic corticosteroid use, immunomodulatory therapy or new target therapy or major IBD-related surgery.

The HR for surgery versus no surgery was significantly lower for both patients with Crohn's disease (adjusted HR 0.63, 0.42 to 0.96) and those with ulcerative colitis (adjusted HR 0.64, 0.45 to 0.92). When stratified by type of bariatric surgery, similar patterns were seen, although statistical significance was reached after Roux-en-Y gastric bypass (unadjusted HR 0.73, 0.57 to 0.92; adjusted HR 0.53, 0.35 to 0.80), but not after sleeve gastrectomy after adjustment (unadjusted HR 0.73, 0.58 to 0.92; adjusted HR 0.73, 0.52 to 1.03).

For the secondary endpoints, there was a statistically significantly lower risk of IBD-related hospitalisation and systemic corticosteroid use among patients with ulcerative colitis, and a lower risk of starting targeted therapy for the overall IBD group, after surgery compared with the no-surgery group.

Including exact BMI in a second matching resulted in 221 patients in the surgery group and 221 matched patients who did not undergo bariatric surgery. During observation, 106 patients (48.0%) in the surgery group and 118 controls (53.4%) reached the composite endpoint (unadjusted HR 0.72, 95% c.i. 0.57 to 0.91; adjusted HR 0.72, 0.50 to 1.02).

“Bariatric surgery was associated with a lower risk of worsening IBD. The risk was reduced both in ulcerative colitis and in Crohn's disease,” the authors stated. “A similar tendency was seen after sleeve gastrectomy as well as Roux-en-Y gastric bypass, but the results were statistically significant only after Roux-en-Y gastric bypass surgery.

The findings were reported in the paper, ‘Outcomes of inflammatory bowel disease in patients with obesity following bariatric surgery: propensity score-matched cohort study’, published inn BJS Open. To access this paper, please click here