title: Platelet-rich plasma for androgenetic alopecia: Does it work? Evidence from meta analysis.
abstract: BACKGROUND
  The use of platelet-rich plasma (PRP) has increased among different surgical specialities for the treatment of various conditions. Androgenetic alopecia is a common condition, with severe attendant psychosocial implications. PRP injections for hair restoration have become a popular practice among plastic surgeons. We performed a meta-analysis comparing local injection of platelet-rich plasma versus control to evaluate this issue in order to investigate the effectiveness of PRP local injections for androgenetic alopecia.
  
  
  METHODS
  A systematic literature search was performed. Primary outcome was the increase in number of hairs. Secondary outcomes were the increase in hair thickness and the percentage increase in hair number and thickness. We performed random-effect analysis.
  
  
  RESULTS
  Six studies involving 177 patients were retrieved and included in the present analysis. A significantly locally increased hair number per cm2was observed after PRP injections versus control (mean difference (MD) 17.90, 95%CI 5.84-29.95, P=.004). Similarly, a significantly increased hair thickness cross section per 10-4mm2(MD 0.22, 95%CI 0.07-0.38, P=.005) favoring PRP group. The pooled results did not show statistically significant differences in percentage increase in hair number (MD 24.12%, 95%CI -12.76-60.99, P=.20) and hair thickness (MD 32.63%, 95%CI -16.23-81.48, P=0.19) among patients treated with PRP.
  
  
  CONCLUSIONS
  Local injection of PRP for androgenic alopecia might be associated with an increased number of hairs and some hair thickness improvement in the treated areas with minimal morbidity. The results of this meta-analysis should be interpreted with caution as it consists of pooling many small studies. Larger randomized studies can verify this perception.
authors.affiliation: Department of Plastic and General Surgery, Turku University Hospital, Turku, Finland.|Department of Surgery, Welfare District of Forssa, Forssa, Finland.
authors.forename: Salvatore
authors.identifier: http://orcid.org/0000-0001-5981-6870
authors.initials: S
authors.lastname: Giordano
authors.affiliation: Department of Plastic Surgery, Jiménez Diaz Foundation and the Autonomous University of Madrid, Madrid, Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: Romeo
authors.affiliation: Department of Orthopaedics and Traumatology, Turku University Hospital and the University of Turku, Turku, Finland.
authors.forename: Petteri
authors.initials: P
authors.lastname: Lankinen
mesh_terms: D000505:Alopecia / Q000628:therapy*; D018859:Hair Follicle; D006801:Humans; D007271:Injections, Intradermal; D053657:Platelet-Rich Plasma; D045506:Therapeutic Uses
chemical_list: D045506:Therapeutic Uses
keywords: androgenetic alopecia; hair growth; hair restoration; platelet-rich plasma(PRP)