P1-369 The association between oral contraceptive use and bone mass in both young and older women

Introduction The association between oral contraceptive use and bone mass remains inconclusive. Aim To describe the associations between current and ever use of OC, bone mass and vertebral deformity in population-based samples of women. Methods Data were collected from women aged 26–36 years (n=687) in the Childhood Determinants of Adult Health study and aged 50–80 years (n=491) in the Tasmanian Older Adult Cohort study. OC use was assessed by questionnaire. Bone mass and vertebral deformity were measured by either quantitative ultrasound or dual-energy x-ray absorptiometry. Analysis Multivariable linear regression analysis was employed to examine the associations between OC use and bone mass with adjustment for confounders. Logistic regression analysis was used to investigate the associations between OC use and the presence of vertebral deformity. Results In young women, current OC use was associated with higher broadband ultrasound attenuation (BUA, β=0.21), speed of sound (SOS, β=0.23) and quantitative ultrasound index (QUI, β=0.23) (all, p Conclusion OC use is consistently associated with higher bone mass in both young and older women in these population-based samples.