A Randomized, Assessor-Blinded, Intraindividual Study on the Efficacy of Fractional Carbon Dioxide Laser Versus Long-Pulsed 1064 nm Nd:YAG Laser in the Treatment of Keratosis Pilaris

Clinical photos were taken at baseline and 4 weeks after the last laser session using a 48-megapixel camera (iPhone 15 Pro Max, Apple). Initial assessment of the photographs was performed by the primary investigator and reviewed and verified by a blinded-board certified dermatologist. The scoring system was adapted from the Physician's Global Assessment (PGA) scoring. Baseline clinical scores for follicular keratotic papules were graded as follows: grade 1, mild = 0-25%; grade 2, moderate = 26-50%; grade 3, severe = 51-75%; grade 4, very severe = 76-100%. Erythema and pigmentation were graded as none, faint, moderate, and intense (1 to 4). Clinical improvement or worsening was rated as follows: grade -4, severe worsening >75%; grade -3, marked worsening 51-75%; grade -2, moderate worsening 26-50%; grade -1, slight worsening 0-25%; grade 0, no improvement; grade 1 mild improvement 0%-25%; grade 2, moderate improvement 26%-50%; grade 3, marked improvement 51-75%; grade 4, excellent impr

A dermoscope (Illuco IDS-1100) with polarized and non-polarized modes was used to assess the dermoscopic findings. Dermoscopic photographs were initially assessed by the primary investigator and reviewed and verified by a blinded board-certified dermatologist with a certification in dermoscopy. Dermoscopic scores (0 to 5) for a fixed area on each treatment area were calculated at baseline and at follow-up, with perifollicular erythema graded as none, faint, moderate, and brownish (0 to 3). Coiled hair and hyperkeratosis were marked as present (1) or absent (0). These numbers were totaled per treatment area and were expressed as mean scores.

Pain scores were evaluated after each laser treatment using a 10-point visual analogue scale (VAS), where 0 indicated no pain and 10 indicated extreme pain. At the end of the study, participants rated their overall satisfaction with treatment on a 5-point scale, with 0 indicating no improvement and 4 indicating excellent improvement.

Patient satisfaction was graded at the end of the study based on their overall satisfaction with the laser treatment, as follows: 0 (unsatisfied), 1 (poor), 2 (fair), 3 (satisfied), 4 (extremely satisfied). This was adapted from the Client Satisfaction Questionnaire-4 (CSQ-4).