The aim of the study was to evaluate whether combined oral contraceptives (COCs) can be used as hormone therapy (HT) to preserve bone mineral density (BMD) in women with premature ovarian insufficiency (POI).
An observational study of women with POI comparing the use of COC (ethinylestradiol 30 μg + levonorgestrel, continuously) with: low-dose HT (continuous conjugated estrogen 0.625 mg plus medroxyprogesterone or continuous estradiol [E2] 1 mg + norethisterone), high-dose HT (continuous conjugated estrogen 1.25 mg + medroxyprogesterone or continuous E2 2 mg + norethisterone), tibolone 2.5 mg, or no treatment. Bone density scans were performed every 2 ± 1 years. The difference between final and initial (delta) BMD values was calculated for the lumbar spine, total femur, and femoral neck. Generalized estimating equations were used to analyze the effect of treatment over time. Variables without normal distribution were transformed into ranks.
Overall, 420 scans (210 deltas) of 119 women were analyzed. The women were 30.3 ± 9.2 years old (mean ± SD). BMD deltas at the lumbar spine and total femur were grater in the COC and high-dose HT groups. At the lumbar spine, the differences between two scans were greater in the COC group when compared to low-dose HT group: −0.043 (95% CI −0.062 to −0.024), untreated: −0.056 (−0.080 to −0.032), and tibolone: −0.050 (−0.094 to −0.006) groups. Total femur BMD decreases and the delta were lower in the low-dose HT group −0.038 (−0.052 to −0.024) when compared to COC.
Continuous COC was associated with increased BMD in women with POI compared to low-dose HT, with similar improvement in the COC and high-dose HT groups.