Clinical and Genetic Predictors of Response to Narrowband UVB for the Treatment of Chronic Plaque Psoriasis.

Br J Dermatol. 2010 Aug 13.
Ryan C, Renfro L, Collins P, Kirby B, Rogers S.
Department of Dermatology St Vincent's University Hospital, Dublin, Ireland.

Summary Background There is considerable variability in the number of exposures of narrowband UVB (NB-UVB) needed to clear psoriasis and in the duration of remission.

Objectives We assessed clinical parameters as predictors of the number of exposures needed to clear psoriasis and the duration of remission. The influence of genetic polymorphisms of the vitamin D receptor (VDR) on treatment response was also evaluated.

Patients and methods This was a prospective study of 119 patients with chronic plaque psoriasis treated with NB-UVB until clearance was achieved. They were then followed for up to one year or until relapse occurred. The frequency of the Fok1, Apa1, Bsm1, Taq1 and rs4516035 polymorphisms of the VDR gene was assessed in 93 of the 119 patients.

Results Of the 119 patients, 105 completed the course of phototherapy. Ninety-nine (94%) cleared in a median of 26 exposures (interquartile range 19-35) with a median remission duration of 16 weeks (interquartile range 9-22). Using an intention to treat analysis, 83% of the initial cohort (99 of 119 patients) achieved clearance. Factors significantly associated with a lower number of exposures to clearance included a lower baseline PASI (p=0.004), lower baseline DLQI (p=0.047), female sex (p=0.043), lower body weight (p=0.008), and a higher number of previous courses of TL01 (p=0.005). The only clinical factor influencing remission duration was number of exposures (p=0.0009) with a decreased remission duration in those who required a greater number of exposures to clear. The Taq 1 VDR polymorphism (rs731236) also significantly predicted remission duration (p=0.038). Patients homozygous for the C allele, which is associated with decreased activity of the VDR, had a shorter remission duration than those heterozygous for the allele (p=0.026) and those homozygous for the T allele (0.013).

Conclusion This study highlights the fact that both genetic and clinical parameters are important in determining treatment outcomes in psoriasis. PMID: 20716226