Effect of cold air cooling on the incidence of postinflammatory hyperpigmentation after Q-switched Nd:YAG laser treatment of acquired bilateral nevus of Ota-like macules

Abstract

Objective: To investigate the effect of cold air cooling on the incidence of postinflammatory hyperpigmentation (PIH) after laser treatment in Asian patients. Design: Randomized, controlled, split-face study. Setting: Skin laser center of a university hospital. Patients: Twenty-three Thai women with acquired bilateral nevus of Ota-like macules. Interventions: Patients were treated using a 1064-nm Q-switched Nd:YAG laser at an average fluence of 7.0 J/cm2 using a 3-mm spot size. The same laser fluence was used on both sides of the face in individual patients. One randomly selected face side of each patient was cooled using a cold air cooling device during and 30 seconds before and after laser irradiation, and the other side was irradiated without cooling. Main Outcome Measures: Occurrence of PIH was objectively evaluated by measuring the melanin index using a spectrometer, and it was subjectively assessed by 2 non-treating physicians before treatment and once weekly for 4 weeks. Results: Of the 21 patients who completed the study, 13 (62%) and 5 (24%) developed PIH on the cooled and uncooled sides, respectively. One patient (5%) had PIH on both the cooled and uncooled sides, and 2 (10%) did not experience PIH. The cooled sides were significantly more likely to become hyperpigmented after laser irradiation than the uncooled sides (relative risk, 2.6; 95% confidence interval, 1.13-6.00; P=.03). The clinical evaluation corresponded to the spectrometer reading. Conclusion: Epidermal cooling with cold air is associated with an increased risk of PIH after Q-switched Nd: YAG laser treatment. Trial Registration: clinicaltrials.gov Identifier: NCT00287001. ©2007 American Medical Association. All rights reserved.