Investigation of suitable starting doses of narrowband UVB in Asian vitiligo patients: a pilot study

Background: Phototherapy is the preferred treatment modality for active and generalized vitiligo. One of the widely accepted consensus on starting dose of phototherapy is using a uniform dose of 280 mJ/cm² regardless of patients' Fitzpatrick skin phototype (SPT). However, in many clinical experiences with Asian vitiligo patients, the protocol seems suboptimal. Objective: To gather more evidence on establishing a higher starting dosage for Asian vitiligo patients undergoing phototherapy. Methods: We enrolled generalized vitiligo patients with lesions sized adequate enough for phototest. Minimal erythema dose (MED) of vitiligo lesion and non-lesion was measured along with melanin index (MI). Results: Relatively, a wide range of MED and MI was observed even among patients with similar SPT. The range of MED for lesional skin was 300–700 mJ/cm² and the MED for non-lesion was 500–800 mJ/cm². Correlation was noted between lesional MED and non-lesional MI (Spearman correlation, ρ = 0.664 [P < 0.036]) and mean lesional MED was approximately 65% of mean non-lesional MED. Conclusion: Results from phototest and tolerability of patients to doses higher than 280 mJ/cm² may indicate that higher starting doses might be appropriate for Asian vitiligo patients.