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Am Fam Physician. 2022;105(1):84-85

Author disclosure: No relevant financial relationships.

Clinical Question

Are intradermal injections of autologous platelet-rich plasma an effective treatment for androgenic pattern hair loss?

Evidence-Based Answer

Platelet-rich plasma injections more effectively increase hair density vs. usual treatment in men with androgenic alopecia. (Strength of Recommendation [SOR]: A, three meta-analyses of randomized controlled trials [RCTs] and cohort studies.) Platelet-rich plasma injections in men are also more effective than minoxidil, 5-alpha reductase inhibitors, and bimatoprost, but not low-level laser therapy. (SOR: A, network meta-analysis of RCTs.) Platelet-rich plasma injections pose little risk of serious adverse events. (SOR: A, meta-analysis of RCTs and cohort studies.) Platelet-rich plasma would be considered an off-label use because it does not have approval from the U.S. Food and Drug Administration for the treatment of androgenic alopecia.

Evidence Summary

A 2020 systematic review and meta-analysis of 13 RCTs (N = 343) examined the effectiveness of platelet-rich plasma injections for androgenic alopecia.1 Seven studies (n = 171; participants were 18 to 65 years of age and 58% were men) examined hair density changes from baseline. One study randomized people to platelet-rich plasma vs. placebo injections in an unblinded fashion. In the other six trials, patients blinded to treatment assignment randomly received injections of platelet-rich plasma on one-half of their head and a placebo on the other. In one study, minoxidil or finasteride (Propecia) was added to both the placebo and platelet-rich plasma injection groups. Patients had two to five platelet-rich plasma injections over the course of two months, with follow-up of three to six months. At follow-up, hair density per cm2 was compared with baseline. Pooled data favored the platelet-rich plasma group with a mean difference of 30.4 (95% CI, 1.8 to 58.9). Normal hair density is approximately 160 to 250 hairs per cm2. Considerable heterogeneity was noted (I2 = 100%). Variations in platelet-rich plasma preparation, injection frequency and methods, and time to follow-up should also be noted as potential confounding factors.

A 2020 systematic review and meta-analysis of 30 RCTs and cohort studies (N = 687) compared one to six treatments of platelet-rich plasma for up to six months with placebo, minoxidil with finasteride, placenta extract, unspecified medical treatment, or no comparison in men and women 18 to 72 years of age.2 Four RCTs and one clinical controlled trial allowed for quantitative analysis; placebo was the control in four studies, and a different platelet-rich plasma method was the control for the fifth. All five trials (n = 123; 54% of participants were men) were analyzed for hair density, and two of the RCTs (n = 70; 43% of participants were men) were analyzed for hair thickness compared with baseline. The studies noted mean differences of 27.9 (95% CI, 14.9 to 40.8) for hair density and 28.8 (95% CI, 12.5 to 45) for hair thickness, both favoring platelet-rich plasma. Heterogeneity was low for hair density (I2 = 21%) and high for hair thickness (I2 = 97%). Three of the five RCTs in this meta-analysis were included in the review by Dervishi and colleagues,1 with a 59% overlap of patients. Risk-of-bias assessment included in the meta-analysis demonstrated a low risk of bias in three trials, uncertain risk in one, and high risk in one. One-half of the 30 studies reported on adverse events as a secondary outcome, with no adverse events reported to be “severe.”

A systematic review and network meta-analysis of 40 RCTs published between 1986 and 2019 (N = 7,545; 75% of participants were men; mean ages were 25 to 56 years) compared platelet-rich plasma treatments, which were given for up to three months with 14 to 39 weeks of follow-up, with other usual treatments.3 No trials met inclusion criteria for platelet-rich plasma treatment in women. The network analysis comparing nonsurgical treatments in men was comprised of 30 RCTs (n = 5,679), four of which included platelet-rich plasma trials (n = 122). The network analysis comparators included low-level laser therapy, oral finasteride (1 mg daily), oral dutasteride (Avodart; 0.5 mg daily), minoxidil solution (2% or 5% twice daily), bimatoprost (various formulations), or placebo. Primary outcomes included hair density per cm2 and a surface under the cumulative ranking curve (SUCRA) score. Platelet-rich plasma was significantly more effective vs. all comparators except low-level laser therapy (mean difference = 12.2 hairs per cm2 favoring platelet-rich plasma; 95% CI, −7.6 to 32.1). The authors deemed the evidence to be low quality and concluded that they could not make a recommendation for or against the use of platelet-rich plasma. The only high-quality evidence was associated with 5% minoxidil.

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Help Desk Answers provides answers to questions submitted by practicing family physicians to the Family Physicians Inquiries Network (FPIN). Members of the network select questions based on their relevance to family medicine. Answers are drawn from an approved set of evidence-based resources and undergo peer review. The strength of recommendations and the level of evidence for individual studies are rated using criteria developed by the Evidence-Based Medicine Working Group (https://www.cebm.net).

The complete database of evidence-based questions and answers is copyrighted by FPIN. If interested in submitting questions or writing answers for this series, go to https://www.fpin.org or email:  questions@ fpin.org.

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

A collection of FPIN’s Help Desk Answers published in AFP is available at https://www.aafp.org/afp/hda.

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