Abstract
BACKGROUND: Metabolic syndrome has been associated with both gallstones and psoriasis, suggesting a potential biological linkage between gallstones and psoriasis. However, the association between gallstones and psoriasis has not yet been studied. OBJECTIVES: To investigate the association between gallstones and psoriasis. METHODS: This was a prospective cohort study [Nurses' Health Study II (1991-2005)]. Women aged 25-42 years who were free from psoriasis at baseline and who responded to a 2005 follow-up questionnaire regarding their diagnosis of psoriasis were included (n = 89,230). The relative risk (RR) of developing psoriasis or psoriatic arthritis (PsA), which were self-reported and validated by supplemental questionnaires, was measured. RESULTS: In this population, 2206 participants had gallstones confirmed by a history of cholecystectomy at baseline. A total of 642 individuals had a diagnosis of incident psoriasis, of whom 157 had concomitant PsA. After adjusting for known risk factors of psoriasis besides body mass index (BMI), a baseline history of cholecystectomy-confirmed gallstones was associated with increased risk of psoriasis [multivariate-adjusted RR 2·20, 95% confidence interval (CI) 1·56-3·10] and concomitant PsA (multivariate-adjusted RR 4·41, 95% CI 2·70-7·18). After additionally adjusting for BMI, the fully adjusted RRs associated with a history of cholecystectomy-confirmed gallstones were 1·70 (95% CI 1·20-2·41) for psoriasis and 2·96 (95% CI 1·80-4·89) for PsA. CONCLUSIONS: Personal history of gallstones was associated with an increased risk of psoriasis and PsA, independent of obesity, in a cohort of U.S. women.