(P-115) Comparison of Rheumatic Patients Across Body Mass Index Categories

Background: Abnormal body mass index (BMI) has been associated with worse rheumatic markers in psoriatic arthritis (PsA) and rheumatoid arthritis (RA).

Objectives: To describe PsA and RA patients in Switzerland, stratified by BMI category.

Methods: A descriptive cohort study in PsA and RA patients registered in the Swiss Clinical Quality Management in Rheumatic Diseases (SCQM) registry - 1996 to Aug. 2019 - was conducted. PsA and RA patients were analyzed as distinct cohorts, with similar approach. New users of biologics or targeted synthetic disease-modifying anti-rheumatic drugs (tsDMARDs) were included, and treatment start was index date. Patients without baseline BMI were excluded. Patients were stratified by BMI category at index, as underweight (BMI <18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), and obese (BMI≥30). The PsA underweight and normal weight categories were merged due to numbers. Obesity prevalence was compared to national figures from the Swiss Federal Statistical Office (FSO). Information on patient demographics, disease-specific characteristics, comedications and comorbidities at baseline were summarized, as well as age at disease onset. Patient characteristics across BMI categories were compared to the normal weight group. Secondarily, correlation between BMI and patient’s characteristics was assessed. Additionally, stratifying by BMI, prescription patterns and reasons for treatment stop were summarized.

Results: The study included 819 PsA [39.7% normal weight, 36.5% overweight, 23.8% obese] and 3217 RA patients [4.4% underweight, 46.8% normal weight, 31.8% overweight, 17.0% obese]. Obesity prevalence in PsA and RA was higher than the national average (11% in 2017, Swiss FSO). Comparing obese patients to those with normal weight, both PsA and RA obese patients had significantly (p < 0.05) higher C-reactive protein, worse disease activity score, and lower quality of life (QoL). Among PsA patients, the obese had significantly worse skin manifestation and pain vs to the normal weight group. While in RA, the obese had significantly higher erythrocyte sedimentation rate, fewer seropositive patients, higher tender joint counts, but similar swollen joint counts, vs the normal weight group. In both cohorts, anti-tumor necrosis factor alpha drugs were the most commonly prescribed biologic/tsDMARD treatment, and reasons for treatment discontinuation were generally similar across BMI categories.

Conclusions: Obesity prevalence in RA and PsA was higher than in the general population. Obese PsA/RA patients presented worse disease activity and poorer QoL than those with normal weight.