Objective: To assess whether psychological distress affects treatment outcome in psoriasis.
Design: Cohort study of patients with psoriasis receiving psoralen-UV-A (PUVA) photochemotherapy.
Setting: Two university hospital dermatology departments.
Patients: One hundred twelve patients with chronic plaque psoriasis.
Main outcome measures: We assessed clinical severity of psoriasis, psychological distress, and other potential confounders of treatment outcome such as skin phototype, family history of psoriasis, and alcohol intake before starting PUVA therapy. Clinical severity of disease and response to therapy were assessed at every fourth appointment.
Results: Pathological or high-level worry was the only significant (P =.01) predictor of time taken for PUVA to clear psoriasis. Event curves of time to clearance significantly differed between high- and low-level worry groups (log rank test, 6.64; df = 1; P =.01). Patients in the high-level worry group cleared with PUVA treatment at a rate 1.8 times slower than that of the low-level worry group (ExpB = 1.81; 95% confidence interval, 1.13-2.90). Fiftieth percentile time to clearance of psoriasis in the high- and low-level worry groups showed a median difference of 19 days.
Conclusions: Psychological distress, in the form of excessive worrying, has a significant and detrimental affect on treatment outcome in patients with psoriasis. Patients with psoriasis who are classified as high-level worriers may benefit from adjunctive psychological intervention before and during treatment. These findings provide further evidence of the existence of a brain-skin axis.