IMPORTANCE Keratosis pilaris (KP) is a common skin disorder of follicular prominence and erythema that typically affects the proximal extremities, can be disfiguring, and is often resistant to treatment. Shorter-wavelength vascular lasers have been used to reduce the associated erythema but not the textural irregularity. OBJECTIVE To determine whether the longer-wavelength 810-nm diode laser may be effective for treatment of KP, particularly the associated skin roughness/bumpiness and textural irregularity. DESIGN, SETTING, AND PARTICIPANTS We performed a split-body, rater-blinded, parallel-group, balanced (1:1), placebo-controlled randomized clinical trial at a dermatology outpatient practice of an urban academic medical center from March 1 to October 1, 2011.We included all patients diagnosed as having KP on both arms and Fitzpatrick skin types I through III. Of the 26 patients who underwent screening, 23 met our enrollment criteria. Of these, 18 patients completed the study, 3 were lost to or unavailable for follow-up, and 2 withdrew owing to inflammatory hyperpigmentation after the laser treatment. INTERVENTIONS Patients were randomized to receive laser treatment on the right or left arm. Each patient received treatment with the 810-nm pulsed diode laser to the arm randomized to be the treatment site. Treatments were repeated twice, for a total of 3 treatment visits spaced 4 to 5 weeks apart. MAIN OUTCOMES AND MEASURES The primary outcome measure was the difference in disease severity score, including redness and roughness/bumpiness, with each graded on a scale of 0 (least severe) to 3 (most severe), between the treated and control sites. Two blinded dermatologists rated the sites at 12 weeks after the initial visit. RESULTS At follow-up, the median redness score reported by the 2 blinded raters for the treatment and control sides was 2.0 (interquartile range [IQR], 1-2; P =.11). The median roughness/bumpiness score was 1.0 (IQR, 1-2) for the treatment sides and 2.0 (IQR, 1-2) for the control sides, a difference of 1 (P =.004). The median overall score combining erythema and roughness/bumpiness was 3.0 (IQR, 2-4) for the treatment sides and 4.0 (IQR, 3-5) for the control sides, a difference of 1 (P =.005). CONCLUSIONS AND RELEVANCE Three treatments with the 810-nm diode laser may induce significant improvements in skin texture and roughness/bumpiness in KP patients with Fitzpatrick skin types I through III, but baseline erythema is not improved. Complete treatment of erythema and texture in KP may require diode laser treatment combined with other laser or medical modalities that address redness. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01281644.
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