Monophasic versus biphasic hyaluronic acid filler for correcting nasolabial folds: a systematic review and meta-analysis.

Background Hyaluronic acid (HA) fillers are the most popular dermal fillers for wrinkle correction and facial rejuvenation. Recently, there has been an interest toward classifying HA fillers based on the cross-linking properties into monophasic (MHA) and biphasic (BHA) fillers. We aimed to compare the efficacy and safety outcomes between MHA and BHA fillers for the correction of nasolabial folds (NLFs). Methods We searched Medline, Embase, and CENTRAL for randomized controlled trials (RCTs) that compared MHA filler to BHA filler for individuals with moderate-to-severe bilateral NLFs. We sought to evaluate the following outcomes: Wrinkle severity rating scale (WSRS), pain on visual analog scale (VAS), global aesthetic improvement scale (GAIS), and adverse events. The standardized mean difference (SMD) was used to represent continuous outcomes while risk ratio (RR) was used to represent dichotomous outcomes. Results A total of 11 RCTs that enrolled 935 participants deemed eligible. MHA filler revealed a significant improvement in the overall WSRS score and GAIS score compared to BHA filler (SMD = -0.38, 95% CI -0.49 to -0.27 and SMD = 0.34, 95% CI 0.24-0.45, respectively). No significant difference was noted between MHA and BHA fillers in terms of pain score or adverse events (SMD = -0.39, 95% CI -0.81-0.03 and RR = 1.00, 95% CI 0.89-1.12, respectively). Conclusions MHA filler showed discernable cosmetic results and comparable effective and tolerability to BHA filler.