Olsen Finasteride 5-year Trial: A Plain-English Overview of What It Established

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See the public record for Finasteride

The five-year report was published in the European Journal of Dermatology in 2002 by the Finasteride Male Pattern Hair Loss Study Group [1]. The earlier 1998 report of the one- and two-year results appeared in the Journal of the American Academy of Dermatology [2].

The design was two 1-year, placebo-controlled Phase III trials that randomized 1,553 men with male pattern hair loss to finasteride 1 mg per day or placebo, followed by up to four 1-year, placebo-controlled extension studies in which 1,215 men continued [1]. The Propecia label describes the same programme: of the men who completed the first 12 months of the two vertex baldness trials, 1,215 continued in double-blind, placebo-controlled 12-month extensions, and 547 men received Propecia in both the initial study and the first extension year [3].

What five years showed

Hair improvement on finasteride was durable across the five years and the difference from placebo was statistically significant on every endpoint, while placebo-treated men lost hair progressively [1]. The authors concluded that 1 mg per day for five years was well tolerated, produced durable hair growth, and slowed the further progression of hair loss that occurs without treatment [1]. Before this report, efficacy and safety beyond two years had not been published for this population [1].

The hair-count numbers, read correctly

Hair was counted in a 1-inch diameter circle, 5.1 cm2, on balding vertex scalp, with an average baseline of 876 hairs [2]. Finasteride was 107 hairs above placebo at one year and 138 above at two years, with P<0.001 for all comparisons, while placebo-treated men lost hair progressively [2]. Those figures are differences between the finasteride and placebo groups, not the finasteride group's own change from baseline.

Safety

In the three controlled 12-month trials of finasteride 1 mg (945 men on the drug, 934 on placebo, all aged 18 to 41), decreased libido was reported by 1.8% of men on finasteride versus 1.3% on placebo, erectile dysfunction by 1.3% versus 0.7%, and ejaculation disorder by 1.2% versus 0.7% [3]. Taken together, 3.8% of men on finasteride reported at least one of these versus 2.1% on placebo (p=0.04) [3]. Resolution occurred in the men who stopped because of these effects and in most of those who continued, and the incidence of each fell to 0.3% or lower by the fifth year of treatment [3]. The five-year report itself stated that finasteride was generally well tolerated and that no new safety concerns emerged during long-term use [1].

Safety reporting in this field has been criticised. A 2015 meta-analysis of 34 finasteride trials for androgenetic alopecia found that none had adequate safety reporting [4]. A 2019 meta-analysis of 15 placebo-controlled trials covering 4,495 men estimated the relative risk of sexual dysfunction at 1.66 with finasteride 1 mg (95% CI 1.20 to 2.30) [5]. The current Propecia label lists depression, suicidal ideation and behavior, and sexual dysfunction that continued after stopping as postmarketing reports. The label says these reports are voluntary, come from a population of uncertain size, and a causal relationship cannot reliably be established [3].

Who the results apply to

Participants were men aged 18 to 41 with mild to moderate, but not complete, hair loss; 88% were Caucasian, and the two trials that were extended enrolled men with vertex hair loss [3]. Men over 41, men with complete baldness and women were not included, and Propecia is not indicated for women or children [3]. The label also states that efficacy in bitemporal recession has not been established [3].

What happens when treatment stops

The Propecia label says that withdrawal of treatment leads to reversal of effect within 12 months, and that continued use is recommended to sustain benefit, which should be re-evaluated periodically [3]. Daily use for three months or more is generally necessary before benefit is observed [3]. Finasteride is a Type II 5-alpha-reductase inhibitor; a 1 mg tablet suppresses serum DHT by 65% within 24 hours [3].

What the five-year summary does not state

The abstract of the five-year report states that improvements were significant versus placebo on all endpoints over five years, but it does not give a year-five hair-count difference [1]. The precise hair-count figures quoted on this page come from the one- and two-year report [2].