Interaction effect of psoriasis and chronic kidney disease on the risk of all-cause mortality: a prospective cohort study of NHANES data

The association between psoriasis, chronic kidney disease (CKD) and mortality remains unclear. This study aimed to examine the combined impact of psoriasis and CKD on mortality in a representative sample of US adults.The data for this analysis came from 13 208 participants of the National Health and Nutrition Examination Survey conducted between 2003-06 and 2009-14. Psoriasis was determined through self-reported questionnaire data, while CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or urinary albumin to creatinine ratio (UACR) ≥30 mg/g. A four-level variable was created using the information on psoriasis and CKD, and survival probability was estimated using the Kaplan-Meier method. The survival analysis was conducted using weighted Cox proportional hazards regression models.In a 9.83-year average follow-up period, 539 deaths occurred, with a prevalence of psoriasis in CKD at 2.94% and an all-cause mortality rate of 33.30%. In the multivariable analyses, individuals with both psoriasis and CKD had hazard ratios (HRs) of 5.38 (95% CI 2.43-11.91) for all-cause mortality compared with those with neither psoriasis nor CKD. Participants with both psoriasis and low eGFR had an HR of 6.40 (95% CI 2.01-20.42), while those with both psoriasis and albuminuria had an HR of 5.30 (95% CI 2.24-12.52). A significant interaction between psoriasis, CKD and all-cause mortality was found in the fully adjusted model (P = .026), and a significant synergistic effect between psoriasis and albuminuria was discovered (P = .002). However, the interaction effects between psoriasis, low eGFR and all-cause mortality were only observed in the unadjusted model (P = .036).Screening for psoriasis in individuals at risk for developing CKD may help in risk stratification for all-cause mortality related to psoriasis. The assessment of UACR may be useful in identifying psoriasis at increased risk for all-cause mortality.