Response to treatment for psoriatic arthritis (PsA) may be impaired for people with obesity, particularly if they are starting a tumor necrosis factor (TNF) inhibitor, research suggests.
The study, presented in a poster at the ACR Convergence 2021 virtual meeting, included 310 PsA patients (56.1% women, mean age 51.8 years) with a BMI of 19 kg/m2 or higher who initiated treatment with a TNF inhibitor, interleukin (IL)-17 inhibitor, or oral small molecule (OSM) and were enrolled in the Psoriatic Arthritis Research Consortium between 2016 and 2020.
At baseline, the mean score on the clinical Disease Activity Index for Psoriatic Arthritis (cDAPSA) was 17.3 points, while the mean scores on the patient-reported RAPID3 and Psoriatic Arthritis Impact of Disease (PsAID) measures were 10.9 and 3.6 points, respectively.
Stratification by BMI category showed that patients with obesity (BMI ≥30 kg/m2; n=126) had a smaller improvement in disease activity than those who were overweight (BMI=25 to <30 kg/m2; n=99) or of normal weight (BMI=19 to <25 kg/m2; n=79), with a mean reduction of 1.42 versus 2.29 and 2.91 points , respectively, as measured on the cDAPSA.
The same pattern was observed when treatment response was assessed using RAPID3, with a mean decrease from baseline of 0.26 points for those in the obese BMI category versus 1.69 and 1.53 points among those in the overweight and normal weight BMI categories, respectively. The corresponding mean reduction in PsAID scores were 0.17 versus 0.72 and 0.58.
The between-group differences for any of the measures were not statistically significant before or after adjustment for age and sex, “potentially due to sample size,” according to Emily Purcell, from the University of Pennsylvania in Philadelphia, USA, and colleagues.
Among patients taking a TNF inhibitor, those with obesity had similar smaller improvements in response measures than those with overweight or normal weight. But there were no such differences between BMI groups among patients taking an IL-17 inhibitor or OSM.
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