Objectives
Both overall and central obesity has been associated with risk of psoriasis from prospective study. Data on the association between obesity and psoriatic arthritis (PsA) have been very sparse and no evidence on obesity measures and risk of incident PsA is available now. We aimed to evaluate the association between obesity and risk of incident PsA in a large cohort of women.
Methods
A total of 89,049 participants were included from the Nurses Health Study II over a 14-year time period (1991–2005). Information on BMI, weight change, and measures of central obesity (waist circumference, hip circumference, and waist-hip ratio) was collected during the follow-up. Incidence of clinician-diagnosed PsA was ascertained and confirmed by supplementary questionnaires.
Results
We identified 146 incident PsA cases during 1,231,693 person-years’ follow-up. Among total participants, BMI was monotonically associated with an increased risk of incident PsA. Compared with BMI less than 25.0, the relative risk (RR) was 1.83 for BMI 25.0 through 29.9 (95% confidence interval (CI): 1.15–2.89), 3.12 for BMI 30.0 through 34.9 (95% CI: 1.90–5.11), and 6.46 for BMI > 35.0 (95% CI: 4.11–10.16). There was a graded positive association between weight change from age 18, measures of central obesity, and risk of PsA (P for trend <0.001). The analysis among participants developing psoriasis during follow-up revealed a similar association (P for trend <0.01), indicating an increased risk of PsA associated with obesity among psoriatics.
Conclusion
In this study we provide further evidence linking obesity with risk of incident PsA among U.S. women.