History of psoriasis response to sunlight does not predict outcome of UVB phototherapy.

We prospectively asked 146 consecutive patients starting narrow-band UVB (NB-UVB) for psoriasis about the effects of sunlight on their psoriasis. Eighty-eight (60%) patients reported improvement with sunlight, six (4%) reported worsening, and 52 (36%) had not noted any change in their psoriasis with sunlight exposure. Overall, 101 (69%) were recorded to reach clearance or minimal residual activity (MRA), 24 (16.5%) to achieve moderate improvement, and 21 (14.5%) had other recorded outcomes (mainly 'did not attend'), with UVB phototherapy. Forty-two (72%) of the 58 who did not report improvement with sunlight went on to clearance/MRA with UVB compared to 59/88 (67%) of those who did report improvement (95% confidence interval for difference in percentage improving, -10% to 20%, P = 0.49). Patients' replies to questions about how their psoriasis responds to sunlight do not appear to predict response to UVB phototherapy in our patient population.