Background: Statins have been shown to downregulate immune mechanisms activated in psoriasis. However, previous studies on their potential role in preventing psoriasis have yielded conflicting results.
Objectives: To assess the relationship between adherence to statins and the risk of psoriasis.
Methods: This retrospective cohort study included 205,820 health plan enrollees in Israel (mean age 55 years; 54·1% women) who initiated statin treatment from January 1998 through to September 2009. Adherence to statins, measured by the proportion of days covered (PDC), throughout the entire follow-up period (mean 6·2 years) was recorded. Diagnosis codes of psoriasis were assigned by a dermatologist or rheumatologist, or at discharge from hospital.
Results: During 1·28 million person-years (PY) of follow-up (median 5·74 years per person; interquartile range 3·78-8·36), 5615 cases of psoriasis (incidence density rate 4·4 per 1000 PY) were recorded. Compared with patients who did not adhere to statins (PDC < 20%), patients covered by statins for 40-59% of the time had a significantly lower risk of psoriasis (P < 0·05), with hazard ratios (HRs) of 0·84 and 0·74 among men and women, respectively. Among patients who adhered better to statins (PDC ≥ 80%), HRs were 0·88 (95% CI 0·79-0·98) and 1·00 (95% CI 0·90-1·11) among men and women, respectively.
Conclusions: The results of the current study suggest that high and long-term adherence to statins is not associated with a meaningful reduction in the risk of developing psoriasis.
© 2015 British Association of Dermatologists.