Efficacy of Q-Switched and picosecond lasers for acquired bilateral nevus of Ota-like macules: a systematic review and exploratory dose-response meta-analysis.

Acquired bilateral nevus of Ota-like macules (ABNOM) is a common dermal melanocytosis predominantly affecting East Asian women. Q-switched (QS) and picosecond (PS) lasers are widely used, but their comparative efficacy and dose-response relationships have not been quantified. We conducted the first systematic review and dose-response meta-analysis to compare PS versus QS laser efficacy for isolated ABNOM. Eleven databases were searched from inception to May 27, 2026. Forty studies (50 treatment arms) of predominantly single-arm case series were included. The primary analysis used generalized linear mixed models (GLMM) for ≥ 75% clearance, complemented by dose-response meta-regression with cluster-robust standard errors. Pooled ≥ 75% clearance was 47.8% (95% CI 13.4-84.4) for PS and 53.1% (95% CI 30.3-74.6) for QS lasers (P = 0.95). Each additional treatment session was associated with a 3-fold increased odds of clearance (OR 3.2; 95% CI 2.4-4.3; P < 0.001). As an exploratory analysis, the dose-response relationship was monotonic across sessions 1-7. The PS estimate was fragile, ranging from 47.8% to 88.7% across sensitivity analyses. GRADE evidence certainty was very low. Treatment session number, rather than laser type, appeared more strongly associated with clearance. However, this dose-response finding remains hypothesis-generating due to very low certainty of evidence and requires validation in randomized trials. The absence of a statistically significant difference between laser types does not establish equivalence; PS efficacy estimates were highly fragile and based on sparse data. Wavelength may be an independent determinant of clearance and warrants further comparative study.