Metformin Not Better Than Oral Contraceptive for Treating PCOS-Related Hirsutism

By Will Boggs MD

September 08, 2020

NEW YORK (Reuters Health) - Metformin monotherapy might be less effective than oral contraceptive pills (OCPs) for treating hirsutism in women with polycystic ovary syndrome (PCOS), according to a new Cochrane review.

In fact, "OCP alone or metformin alone is less effective than combining the 2 treatments for improving hirsutism," Dr. Michael F. Costello of the University of New South Wales and Royal Hospital for Women and IVF Australia, in Sydney, told Reuters Health by email.

Both metformin and OCPs are commonly used to treat the features of PCOS, and some have suggested that metformin might be safer and more effective long-term, Dr. Costello and colleagues note in the Cochrane Database of Systematic Reviews.

The team included 44 randomized controlled trials (RCTs) of 2,047 adult women (39 trials) and 206 adolescent women (five trials) in their analysis.

The evidence quality ranged from very low to low because of poor reporting of study methods and a lack of both precision and consistency in the results.

Metformin monotherapy appeared to be less effective than OCP monotherapy for improving hirsutism in overweight adult women, but the outcomes were uncertain among women with normal BMI (<25 kg/m2) and among obese women (BMI>30 kg/m2).

While severe gastrointestinal adverse events appeared to be more common with metformin than with OCP, metformin appeared to decrease the incidence of other severe adverse events.

Metformin monotherapy and OCP monotherapy appeared to be less effective in improving hirsutism than did their combination.

Among secondary outcomes, menstrual patterns were better with OCP monotherapy than with metformin monotherapy, but acne improved to a similar extent with the two monotherapies. Evidence regarding any impact of these treatments on BMI was rated very low quality.

Based on the limited data, it remains unclear whether there is a difference between metformin and OCP treatment on hirsutism and adverse events in adolescent women.

"OCP is superior to metformin for menstrual regulation and hirsutism," Dr. Costello said. "Metformin is superior to the OCP for effect on BMI (i.e., reducing or improving BMI) in obese women with PCOS, where it reduces BMI by about 2.3 kg/m2 on average."

"Further large well-designed RCTs that stratify for BMI are needed to evaluate metformin versus the OCP and combinations in women with PCOS, in particular adolescent women," the authors conclude.

SOURCE: Cochrane Database of Systematic Reviews, online August 13, 2020.