Patients with both inflammatory bowel disease (IBD) and obesity starting on new biologic therapies do not face an increased risk for hospitalization, IBD-related surgery, or serious infection, reveals a multicenter U.S. study published online in American Journal of Gastroenterology.
“Our findings were a bit surprising, since prior studies had suggested higher clinical disease activity and risk of flare and lower rates of endoscopic remission in obese patients treated with biologics,” Siddharth Singh, MD, MS, director of the IBD Center at the University of California, San Diego, told this news organization.
“However, in this study we focused on harder outcomes, including risk of hospitalization and surgery, and did not observe any detrimental effect,” he said.
Based on the findings, Dr. Singh believes that biologics are “completely safe and effective to use in obese patients.”
He clarified, however, that “examining the overall body of evidence, I still think obesity results in more rapid clearance of biologics, which negatively impacts the likelihood of achieving symptomatic and endoscopic remission.”
“Hence, there should be a low threshold to monitor and optimize biologic drug concentrations in obese patients. I preferentially use biologics that are dosed based on body weight in patients with class II or III obesity,” he said.
Research findings
Dr. Singh and colleagues write that, given that between 15% and 45% of patients with IBD are obese and a further 20%-40% are overweight, obesity is an “increasingly important consideration” in its management.
It is believed that obesity, largely via visceral adiposity, has a negative impact on IBD via increased production of adipokines, chemokines, and cytokines, such as tumor necrosis factor (TNF) alpha and interleukin-6, thus affecting treatment response as well as increasing the risk for complications and infections.
However, studies of the association between obesity and poorer treatment response, both large and small, have yielded conflicting results, potentially owing to methodological limitations.
To investigate further, Dr. Singh and colleagues gathered electronic health record data from five health systems in California on adults with IBD who were new users of TNF-alpha antagonists, or the monoclonal antibodies vedolizumab or ustekinumab, between Jan. 1, 2010, and June 30, 2017.
World Health Organization definitions were used to classify the patients as having normal BMI, overweight, or obesity, and the risk for all-cause hospitalization, IBD-related surgery, or serious infection was compared between the groups.
The team reviewed the cases of 3,038 patients with IBD, of whom 31.1% had ulcerative colitis. Among the participants, 28.2% were classified as overweight and 13.7% as obese. TNF-alpha antagonists were used by 76.3% of patients.
Patients with obesity were significantly older, were more likely to be of Hispanic ethnicity, had a higher burden of comorbidities, and were more likely to have elevated C-reactive protein levels at baseline.
However, there were no significant differences between obese and nonobese patients in terms of IBD type, class of biologic prescribed, prior surgery, or prior biologic exposure.
Within 1 year of starting a new biologic therapy, 22.9% of patients required hospitalization, whereas 3.3% required surgery and 5.8% were hospitalized with a serious infection.
Cox proportional hazard analyses showed that obesity was not associated with an increased risk for hospitalization versus normal body mass index (adjusted hazard ratio, 0.90; 95% confidence interval, 0.72-1.13), nor was it associated with IBD-related surgery (aHR, 0.62; 95% CI, 0.31-1.22) or serious infection (aHR, 1.11; 95% CI, 0.73-1.71).
The results were similar when the patients were stratified by IBD type and index biologic therapy, the researchers write.
When analyzed as a continuous variable, BMI was associated with a lower risk for hospitalization (aHR, 0.98 per 1 kg/m2; P = .044) but not with IBD-related surgery or serious infection.
