Meta-analysis describes the relative effectiveness of common treatments for androgenetic alopecia
To date, the relative effectiveness of the 3 treatments, minoxidil and the 5α reductase (5-ARI) inhibitors finasteride and dutasteride, has remained largely unknown.
In a new study, researchers have shared their findings on the relative effectiveness of 3 commonly used treatments for male androgenetic alopecia (GAA) based on data from more than 20 studies including various forms and dosages of the treatments.
To date, the relative effectiveness of the 3 treatments, minoxidil and the 5α reductase (5-ARI) inhibitors finasteride and dutasteride, has remained largely unknown. The new findings, say the researchers, add to the literature on the comparative effectiveness of treating AGA.
“Many studies have investigated the efficacy of minoxidil and 5-ARIs for the treatment of AGA in humans; however, evidence of their relative effectiveness is sparse. For example, there are no controlled trials on the effectiveness of oral minoxidil for male AGA,” the group explained, writing in JAMA Dermatology. “Recently, the relative effectiveness of oral and topical minoxidil has been examined using network meta-analysis (NMA), but to our knowledge, no study has determined the comparative effectiveness of these 2 agents with that local and systemic dutasteride and finasteride.”
Drawing on the results of 23 trials, the researchers compared data from 15 different regimens of the 3 treatments, concluding that oral dutasteride 0.5 mg/day is likely the most effective treatment for these patients, followed by:
- Oral finasteride 5 mg/day
- Oral minoxidil 5 mg/day
- Oral finasteride 1 mg/day
- 5% minoxidil topical solution
- 2% minoxidil topical solution
- Oral minoxidil 0.25 mg/day
Throughout their analysis, the researchers found that off-label use of dutasteride 0.5 mg/day produced the most significant increases in total hair count at 24 weeks compared to the amount of finasteride approved by the FDA at 1 mg/day and 3 forms of minoxidil. (0.25 mg/day, 5 mg/day and 2% solution). Oral minoxidil has not been approved for the treatment of hair loss, although vendors use it off-label, and both topical strengths of the treatment have received FDA approval.
According to the researchers, the improved efficacy of dutasteride for this parameter compared to finasteride could be attributed to the fact that dutasteride is more potent in inhibiting the type 1 isoenzyme of 5-α reductase and the type 2 isoenzyme.
At 48 weeks, the greatest increase in total hair count was observed with finasteride 5 mg/day, which was significantly more effective than topical minoxidil 2%. There were no data available for oral dutasteride or minoxidil for this outcome.
The researchers also looked at the impact on terminal hair count, finding that at 24 weeks, 5 mg/day of minoxidil was more effective in increasing terminal hair count than 0.25 mg/day of treatment and compared at its 2 topical concentrations. It was also more effective than 1 mg/day of finasteride.
At 48 weeks, finasteride 1 mg/day was associated with the greatest increase in terminal hair count compared to the two topical forms of minoxidil.
“The relative efficacy of 3 or more therapies can arguably be determined more effectively with NMAs than by head-to-head trials; furthermore, this statistical tool allows researchers to produce evidence of comparative efficacy without constraints ethics,” commented the researchers. “However, unlike actual randomized trials, meta-analytic procedures cannot determine causation.
Gupta A, Venkataraman M, Talukder M, Bamimore M. Relative efficacy of minoxidil and 5-α reductase inhibitors in the treatment of androgenetic alopecia in male patients: a network meta-analysis. JAMA Dermatol. Published online February 2, 2022. doi: 10.1001/jamadermatol.2021.5743