Oral contraceptive use and fracture risk-a retrospective study of 12,970 women in the UK

Abstract

In the present retrospective case-control study, we compared 6485 women with fractures and 6485 women without fractures from 135 general practitioner offices in the UK. Women without bone fractures were statistically more likely to have been exposed to oral contraception, depending on their age and therapy duration.

Introduction: The aim of this analysis was to compare the risk of bone fracture in women using hormonal contraception with that in women who have never used hormonal contraception.

Methods: A total of 6485 women (mean age 37.8 years) with an initial diagnosis of fracture between January 2010 and December 2015 were identified in 135 doctors' offices in the UK Disease Analyzer database. In this nested case-control study, each case with a fracture was matched (1:1) to a control without a fracture for age, index year, and follow-up time. In total, 12,970 individuals were available for analysis. The main outcome of the study was the risk of fracture as a function of combined oral contraceptive (OC) therapy. Multivariate logistic regression models were used to determine the effect of OC therapy and its duration on the risk of fracture in the entire population and in four age-specific subgroups.

Results: Women without bone fractures were significantly more likely to have used oral contraception (OR 0.81). The usage of oral contraception was associated with a significantly lower risk of bone fracture (OR 0.81, 95% CI 0.74-0.90). This effect was strongest in the age groups 18-25 and 26-35 and in patients with an OC treatment duration of more than 1 year.

Conclusions: The present study revealed that women without bone fractures were significantly more likely to have had exposure to combined oral contraception, especially where the duration of intake was at least 5 years.

Keywords: Fracture risk; Oral contraceptives; UK; Women.