Comparative appraisal with meta-analysis of picosecond versus nanosecond lasers for hyperpigmented disorders and...

To compare the efficacy and safety of picosecond lasers (PSLs) versus nanosecond lasers (NSLs) for treatment of hyperpigmented disorders and tattoos, we conducted a systematic review of literature. PubMed, Web of Science and Cochrane library (from inception to December 2024) were searched for articles. The primary outcome was the treatment success rate (≥ 75% clearance of pigment), and the secondary outcomes were the visual analogue scale (VAS) to assess pain and the rates of adverse events. We analyzed 20 randomized controlled trials and 1 retrospective comparative study comprising a total of 971 patients. For efficacy, PSLs and NSLs had comparable clearance for endogenous hyperpigmentation (RR 1.06, 95% CI [0.85, 1.31], P = 0.60), but PSLs tend to have superiority (RR 1.39, 95% CI [0.99, 1.94], P = 0.05) for exogenous hyperpigmentation. For pain assessment, the mean value of VAS for PSLs and NSLs was between 1.5 and 5.61 and 1.0 to7.9. Both lasers were tolerable and PSLs led to less pain (P < 0.01). Adverse events including post-inflammatory hyperpigmentation (PIH) and post-inflammatory hypopigmentation (PIHo) were much more obvious in Asian than European patients. Meanwhile, compared with NSLs, PSLs had significantly less rate of PIH (P = 0.02; I² = 28%) and PIHo (P = 0.002; I² = 13%). This systematic review suggests that PSLs had comparable efficacy with NSLs. Regarding safety, the superior profile of PSLs is currently best supported in Asian cohorts; data remain sparse for other phototypes.