The use of combined oral contraceptive pills (COCP) and metformin, either as monotherapy or combined, was evaluated for the treatment of polycystic ovary syndrome (PCOS) in a recent systematic review published in the journal Clinical Endocrinology.

Study authors systematically searched electronic databases for applicable randomized controlled trials that assessed these therapies for the management of hormonal and clinical features of PCOS. “Outcomes were prioritized as critical for informing a decision about an intervention or important or not important, according to GRADE,” they explained, adding, “Outcomes prioritized by women and health professionals included: irregular cycles, insulin resistance, weight, BMI, thromboembolic events and gastrointestinal effects.”

A total of 56 eligible studies were included in the review. Analysis of low quality evidence in adolescents revealed metformin to be more effective in managing BMI compared with COCP (mean difference [MD]: -4.02 [-5.23, -2.81]; P <.001), while COCP was found to be superior to metformin for menstrual regulation (MD: -0.19 [-0.25, -0.13; P <.00001).

Results obtained from low quality evidence in adults not only showed metformin to be more effective compared with placebo for BMI (MD ‐0.48 [‐0.94, ‐0.02], P =.04), but also more efficacious vs COCP for fasting insulin (MD: 4.00 [2.59, 5.41], P =.00001). Data analysis from this evidence also revealed COCP to be more effective than metformin for irregular cycles (MD: 12.49 [1.34, 116.62], P =.03). Additionally, COCP was found to be more efficacious alone than in combination with an anti-androgen for BMI (MD: ‐3.04 [‐5.45, ‐0.64], P =.01).

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Safety data obtained during the analysis revealed metformin to be associated with mild gastrointestinal adverse events. The study authors noted that when outcomes were sub-grouped according to a patient’s BMI, differences in statistical significance were observed.  

“Overall, COCP offers effective PCOS treatment ameliorating hyperandrogenism and cycle irregularity with no advantage of specific subtypes of COCP,” the study authors concluded. They added, “We clarify the role of metformin alone or in combination with COCP showing it is useful for the management of metabolic features of PCOS specifically weight, hormonal, and metabolic outcomes, especially in women with PCOS with a BMI≥25kg/m².”

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