Background Depo-Provera is one of the most widely-used contraceptives. The side-effects includes loss in bone mineral density (BMD), increasing fracture risk (1,2). It is not known if conventional fracture risk factors impact fracture risk in these patients.

Objectives We set out to determine if the usual risk factors for fracture are associated with increased risk of fragility fractures in patients exposed to Depo-Provera.

Methods Patients referred for bone densitometry at a scanner in North West of England were analysed. Femoral and vertebral BMD, height, weight and body mass index (BMI) were recorded, in addition to: age, diagnosis of rheumatoid arthritis, smoking status, alcohol consumption, family history of fractures, history of secondary osteoporosis, corticosteroid use, total average proportion fat, average tissue thickness, fat mass, and lean mass. Patients with exposure to Depo-Provera were selected for analysis. Initially patients with and without a fracture were compared using Chi-squared test and T-test. Logistic models were fitted univariately and adjusted for age to analyse association between traditional risk factors and fracture.

Results 304 females (103 currently and 201 previously on Depo-Provera) were included. 62 (20.4%) had sustained had least one fragility fracture. There was no significant difference in fracture risk between those currently and previously on Depo-Provera (p=0.176 95% CI). Decreased left femoral BMD significantly impacted fracture risk (p=0.035 95% CI). All other factors investigated did not significantly increase fracture risk in this cohort.(see table below)

Conclusions Our study suggests that fragility fractures in patients taking Depo-Provera are not associated with the usual risk factors for fractures. To our knowledge, this is the first study demonstrating fracture risk in such patients to be independent of conventional risk factors. This therefore indicates an as yet unidentified mechanism of increased fracture risk. Study limitations include the small number of fractures and lack of data on length of treatment with Depo-Provera. Further research is needed into the mechanisms by which the drug gives rise to increased fracture risk, independent of other factors.

References

1. Contraception. United States; 2011 Nov;84(5):e31–7.

2. Obstet Gynecol. United States; 2008 Oct;112(4):788–99.

References

Disclosure of Interest None declared