Metabolic syndrome and risk of incident psoriasis: prospective data from the HUNT Study, Norway

Background Metabolic syndrome has been associated with psoriasis in cross-sectional studies, but data from prospective studies are sparse. Objectives To examine prospectively whether metabolic syndrome and its components are associated with the risk of incident psoriasis in a large population-based study using objective measurements of cardiovascular disease risk factors. Methods We used data from two consecutive surveys of the HUNT Study, Norway (HUNT2, 1995-1997, and HUNT3, 2006-2008). In total 34 996 women and men aged >= 20 years without psoriasis in HUNT2 were followed up in HUNT3, and 374 incident cases of psoriasis were identified. We used Cox regression to estimate the adjusted relative risk (RR) of incident psoriasis with its 95% confidence interval (CI). Results Metabolic syndrome was associated with an RR for psoriasis of 1.66 (95% CI 1.30-2.14). To explore the influence of adiposity on this association, we first excluded waist circumference from the definition of metabolic syndrome (adjusted RR 1.54, 95% CI 1.14-2.07) and then adjusted for body mass index (RR 1.33, 95% CI 0.97-1.81). Analyses of the separate components of metabolic syndrome showed positive associations with risk of psoriasis for waist circumference, triglycerides and high-density lipoprotein (HDL) cholesterol, but not for blood pressure or blood glucose. There was also an increased risk of psoriasis for high total cholesterol. The increased risk associated with high triglycerides, HDL cholesterol and total cholesterol was attenuated after adjusting for body mass index. Conclusions In this large prospective study from a general population, we found that metabolic syndrome was associated with increased risk of incident psoriasis, and our results suggest that this positive association could, at least partly, be attributed to adiposity.