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.