Depo-Provera use in teens tied to bone density drop

OB/GYN News, August 1, 2003 by Mitchel L. Zoler

PHILADELPHIA -- Two years of contraception with injectable medroxyprogesterone acetate in adolescent girls was associated with an average 6.8% reduction in bone mineral density, compared with controls in an observational study of 148 teens.

"A 6.8% reduction is clinically significant," Dr. Eduardo Lara-Torre said at the annual meeting of the North American Society for Pediatric and Adolescent Gynecology. "The most important question now is if treatment stops, does bone density normalize?" said Dr. Lara-Torre, a pediatric and adolescent gynecologist at the University of Louisville (Ky).

By itself, this finding should not prompt a change in the use of injectable medroxyprogesterone acetate (Depo-Provera) in adolescent girls, he told this newspaper. Further studies must assess whether the reduction in bone density associated with the drug's use is reversible, or if the effect can be blunted by treatments that increase bone mineral density (BMD), such as calcium supplements or drug interventions.

The study included girls in a pregnancy prevention clinic at the university. Each participant selected the contraceptive method she preferred: 58 girls selected injectable medroxyprogesterone acetate, 71 opted for an oral contraceptive pill, and 19 picked barrier contraception. The average age of the teens in the study was about 15 years old. BMD was determined for each girl at baseline and every 6 months with dual-energy x-ray absorptiometry.

After 6 months, the girls treated with medroxyprogesterone acetate had lost an average of 0.25% of their BMD, compared with their baseline level. In contrast, the girls treated with oral contraceptive pills gained an average of 2.35% of their BMD, and the girls who did not receive a contraceptive drug gained an average of 2.45% of their BMD.

The girls were followed for as long as 24 months, although there was considerable attrition. After 24 months, the 21 girls who remained in the medroxyprogesterone acetate group had an average 1.85% reduction in their BMD, compared with baseline. The five girls who remained in the oral contraceptive group had an average 1.01% reduction in their BMD, compared with baseline. And the six girls who remained in the barrier contraception group had an average 5.89% increase in their BMD, compared with baseline.

The average BMD difference between the medroxyprogesterone acetate and control groups was 6.8%; this difference was statistically significant.

MITCHEL L. ZOLER

Philadelphia Bureau