Differences in body mass index among individuals with PsA, psoriasis, RA and the general population.

To compare obesity among individuals with PsA, psoriasis (PsO), RA and the general population (n), and identify correlates of obesity among individuals with PsO and PsA. We compared the BMI of patients with PsA (n = 644), PsO (n = 448), RA (n = 350) and the general population using age- and sex-adjusted linear and logistic regression analyses. We conducted multivariate analyses limited to PsO and PsA to determine correlates of BMI and obesity. The mean BMI (kilogram per square metre) for individuals with PsA, PsO, RA and the general population were 29.6, 27.9, 27.3 and 26.1, respectively. The proportion with obesity was 37, 29, 27 and 18% for individuals with PsA, PsO, RA and the general population, respectively. The differences in BMI were significant between all categories (P < 0.05) except between PsO and RA. Age- and sex-adjusted linear and logistic regression confirmed that these differences were significant. In multivariate logistic regression analyses adjusted for age, sex, smoking, PsO duration, psoriasis area severity index score, use of DMARDs, glucocorticoids and biologics, the odds of obesity were 61% higher for PsA patients than PsO patients (95% CI 1.10, 2.37). When we additionally adjusted for the physical component summary of the short form-36, the association was attenuated and became insignificant. Individuals with PsA have a higher mean BMI than those with PsO, RA or the general population. The BMI difference between PsA and PsO correlates with physical health.