Synergistic effect of psoriasis and metabolic syndrome on risk of all-cause and cardiovascular mortality in US adults: a nationwide cohort study

Background Metabolic syndrome (MetS) is a common comorbidity in psoriasis. However, the associations between MetS, psoriasis and mortality remain largely unclear. Objectives To investigate the synergistic effect of MetS and psoriasis on total and cardiovascular disease (CVD) mortality in a representative sample of US adults. Methods In total, 14 930 participants from the 2003-2006 and 2009-2014 National Health and Nutrition Examination Survey were included in this prospective, nationwide cohort study. Participants were stratified into the psoriasis-/MetS- (reference) group, psoriasis-/MetS+ group, psoriasis+/MetS- group and psoriasis+/MetS+ group. Results Overall, 14 930 participants, 50.71% were male, with a mean age of 43 years, were included in the final analysis. The weighted percentages of participants in the psoriasis-/MetS-, psoriasis-/MetS+, psoriasis+/MetS- and psoriasis+/MetS+ groups were 72.77%, 24.36%, 1.94% and 0.93%, respectively. In total, 874 deaths (246 of which were related to CVD) occurred during a median follow-up of 110 months. Compared with the reference group, the hazard ratios in the psoriasis-/MetS+, psoriasis+/MetS- and psoriasis+/MetS+ groups were 1.788 [95% confidence interval (CI) 1.486-2.152], 0.858 (95% CI 0.431-1.707) and 2.050 (95% CI 1.028-4.092), respectively, for all-cause mortality, and 1.856 (1.350-2.552), 1.229 (95% CI 0.292-5.181) and 4.571 (95% CI 1.724-12.119), respectively, for CVD mortality. Subgroup analysis showed that this association was not influenced by participants' age, sex, physical activity, smoking, estimated glomerular filtration rate, or urinary albumin/creatinine ratio. Similar results were obtained in the sensitivity analysis of the main results. Conclusions Presence of comorbid MetS significantly increases all-cause and CVD mortality in patients with psoriasis. Dermatologists can potentially aid in reducing mortality rates in patients with psoriasis through targeted screening for MetS.