Increased risk of psoriasis following chronic rhinosinusitis without nasal polyps: a population‐based matched‐cohort study

Background Although chronic rhinosinusitis without nasal polyps (CRSsNP) and psoriasis both share immunological disturbances as pathological factors, no prior study has investigated the risk for psoriasis among patients with CRSsNP. Objectives To investigate the subsequent risk for psoriasis following a diagnosis of CRSsNP by utilizing a cohort study design and a population‐based dataset in Taiwan. Methods In total, 13 242 subjects with CRSsNP were included in the study cohort and 39 726 subjects were randomly extracted for the comparison cohort. We individually tracked each individual in this study (n = 52 968) for a 5‐year period following their index date to identify those subjects who received a subsequent diagnosis of psoriasis. Cox proportional hazards regression analysis was conducted to calculate the 5‐year risk of subsequent psoriasis following a diagnosis of CRS among the sampled subjects. Results The incidence rate of psoriasis during the 5‐year follow‐up period was 1·41 [95% confidence interval (CI) 1·14–1·71] per 1000 person‐years and 0·69 (95% CI 0·59–0·81) per 1000 person‐years for the study and comparison cohort, respectively. Stratified Cox proportional hazards regression revealed that the hazard ratio for psoriasis during the 5‐year follow‐up period for subjects with CRSsNP compared with the control group was 2·01 (95% CI 1·54–2·62) after adjusting for monthly income, geographical region, hypertension, diabetes, coronary heart disease and hyperlipidaemia, and censoring the cases who died during the 5‐year follow‐up period. Conclusion This study detected an increased risk for psoriasis among patients with CRSsNP.