The 1998 Propecia Clinical Trials: Methodology and Results

The Kaufman et al. 1998 publication in the Journal of the American Academy of Dermatology reported the pivotal Phase III trials that supported FDA approval of finasteride 1 mg (Propecia) for male androgenetic alopecia in December 1997. Two identically designed 12-month randomized, double-blind, placebo-controlled trials were conducted in the US and internationally, enrolling approximately 1,553 men total.

Study Design

Parameter	Details
Design	Two identically designed, parallel-group, double-blind RCTs
Population	Men 18–41 years old with mild-to-moderate vertex AGA (Norwood–Hamilton II vertex to V)
Total participants	~1,553 (US study n=1,215; international study n=338)
Treatment arms	Finasteride 1 mg/day vs. placebo; 1:1 allocation
Duration	12 months
Primary efficacy endpoint	Hair count in a defined 1-inch circular area of the vertex scalp at 12 months
Secondary endpoints	Patient self-assessment (questionnaire), investigator assessment (photographic), scalp coverage

Key Results

Outcome	Finasteride 1 mg	Placebo
Hair count change at 12 months (vertex)	+7.1 hairs/cm²	−10.6 hairs/cm²
Net difference	17.7 hairs/cm² advantage for finasteride
Investigator assessment: improved/no change	83%	28%
Investigator assessment: visible improvement	48%	7%
Patient self-assessment: improved	66%	28%
Scalp coverage by photographic assessment	Significantly superior to placebo	—

Limitations

• Participants limited to men 18–41; may not generalize to older men with longer-standing AGA
• Primary endpoint focused on vertex AGA; frontal hairline data were secondary
• 12-month duration; long-term maintenance required data from subsequent 5-year and 10-year studies
• Sponsored by Merck & Co. (manufacturer); standard for pivotal industry-funded RCTs

See also: What is finasteride | Results timeline

Sources

• Kaufman KD, et al. “Finasteride in the treatment of men with androgenetic alopecia.” J Am Acad Dermatol. 1998;39(4):578–589.