Early Intervention With Low‐Fluence Q‐Switched 1064‐nm Nd:YAG Laser is Associated With Improved Clinical Outcomes in Postinflammatory Hyperpigmentation: A Retrospective Cohort Study
Huan Luo, Zhiyong Li, Xuanqi Feng, Jingyu Zhang, Xiao Luo, Hongxiang ChenBackground and Objectives
Traditional postinflammatory hyperpigmentation (PIH) management delays laser intervention until lesion stabilization, potentially forfeiting a critical therapeutic window. This study aimed to evaluate the efficacy and safety of early active (EA) phase initiation of low‐fluence Q‐switched 1064‐nm Nd:YAG laser treatment (4–8 weeks postonset) versus the relatively stable (RS) phase (> 8 weeks postonset).
Materials and Methods
In this single‐center retrospective cohort, 48 PIH patients were stratified by disease duration: 4–8 weeks postonset for the EA‐phase group ( n = 28) and > 8 weeks postonset for the RS‐phase group ( n = 20). All patients received three low‐fluence (1.8–3.0 J/cm 2 ) Q‐switched 1064‐nm sessions at 4‐week intervals. The primary endpoint was objective lesion diameter reduction at 3 months posttreatment, quantified via a multispectral imaging device. Secondary endpoints included the modified Post‐Acne Hyperpigmentation Index (mPAHPI), Physician Global Assessment (PGA), patient satisfaction scores, and safety.
Results
Early intervention was associated with significantly greater objective lesion diameter reduction rate (median 54.46% vs. 13.13%; p < 0.001), greater mPAHPI improvement rate (41.39% vs. 12.13%; p = 0.003), and greater PGA improvement rate (60.00% vs. 25.00%; p = 0.001). Primary multivariable linear regression identified early intervention as an independent predictor for greater objective diameter reduction (unstandardized B = 39.60; p < 0.001), mPAHPI improvement ( B = 23.68; p = 0.001), and PGA improvement ( B = 27.14; p = 0.001). Supporting logistic regression consistently indicated early intervention as an independent predictor of dichotomized clinical success (adjusted odds ratios: 4.815–14.108; all p s < 0.05). Early treatment was associated with significant resolution of baseline erythema (82.1% improvement; p = 0.016). Mild hypopigmentation occurred exclusively in the RS‐phase group (25.0%).
Conclusions
Initiating low‐fluence Q‐switched 1064‐nm laser therapy at 4–8 weeks after PIH onset is associated with enhanced pigment clearance and inflammation resolution compared with delayed intervention, suggesting the potential utility of a stage‐specific paradigm for PIH management.