Treatment of acne scars with fractional carbon dioxide laser in Asians: a retrospective study to search for predicting factors associated with efficacy.

Ablative fractional laser treatment has been extensively used for resurfacing atrophic acne scars. However, few studies have investigated how the parameters set during laser procedures affect efficacy. In this retrospective study, we examined the relationship between efficacy and Fitzpatrick skin type, gender, age, follow-up duration, energy, and treatment sessions utilizing ablative fractional carbon dioxide (CO) laser in Asians with Fitzpatrick skin types III-IV. We then analyzed the relationship between outcome and adverse effects including hyperpigmentation. Three blinded dermatologists used the ECCA (Echelle d'Evaluation Clinique des Cicatrices d'Acnluation Clinique des Cicospectively review 82 of 1034 patients who presented at our institution for atrophic acne scar treatment between August 2013 and August 2019. Factors associated with efficacy, including age, gender, Fitzpatrick skin type, energy, treatment sessions, follow-up duration, and pigmentation, were analyzed. 82 patients met inclusion criteria. Patients underwent one to three CO laser treatment sessions. Parameter settings for individual patients were consistent across treatments. Mean ECCA scores decreased from 102.70 ± 24.95 to 87.28 ± 24.48 (p ≤ 0.001). The number of treatment sessions and duration of pigmentation lasting shorter than 3 months positively correlated with better outcomes. All patients had erythema, which lasted longer than 3 months in 16 patients (19.51%). Post-inflammatory hyperpigmentation (PIH) affected 60 patients (73.17%) and lasted longer than 3 months in 26 patients (31.71%). One patient experienced hypopigmentation (1.22%), while 8 experienced acne flare-up (9.76%). Post-laser scars occurred in 2 patients (2.44%). Our data suggest that in atrophic acne scar treatment in Asians using fractional CO laser, 3 treatment sessions and duration of hyperpigmentation within 3 months have better outcomes regardless of energy, gender, age, Fitzpatrick skin type, follow-up duration, and disease course.