Pos0503 risk of cardioembolic ischaemic stroke among new users of oral bisphosphonates: a nested case-control study

Background Bisphosphonates have been associated with atrial fibrillation, but studies carried out thus far have not shown that they are also associated with an increased risk of ischaemic stroke (IS). None, however, separated by IS subtype (cardioembolic vs non-cardioembolic). Objectives The present study aimed to test the hypothesis that use of oral bisphosphonates (oBs) increases specifically the risk of cardioembolic IS. Methods A nested case-control study was performed using the Spanish primary healthcare database BIFAP (period: 2002-2015). Incident cases of IS were identified and classified as cardioembolic or non-cardioembolic. Five controls per case were randomly selected, matched for exact age, sex, and index date (first recording of IS). The association of IS (overall and by subtype) with the use of oBs within the last year before index date was assessed by computing the adjusted odds ratios (AOR) and their corresponding 95%CI using conditional logistic regression. Only oBs initiators were considered. (Figure 1). Results A total of 4,568 cardioembolic IS cases (matched with 21,697 controls) and 9,213 non-cardioembolic IS cases (matched with 44,212 controls) were included. For cardioembolic IS, the use of oBs was associated with an AOR of 1.35(1.10-1.66), in a duration dependent manner (AOR≤1year=1.10;0.82-1.49; AOR>1-3years=1.41;1.01-1.97; AOR>3years=1.81;1.25-2.62; p for trend=0.001). Such increased risk only appeared when patients used concomitantly calcium supplements and was completely blunted by anticoagulants. No increased risk was observed for non-cardioembolic IS (AOR=1.03;0.88-1.21). Conclusion The long-term use of oBs with calcium supplements increases the risk of cardioembolic IS, while leaves materially unaffected the risk of non-cardioembolic IS. Figure 1. Acknowledgements The authors would like to acknowledge the excellent collaboration of the primary care physicians (general practitioners/paediatricians), as well as the support from the regional health administrations providing BIFAP data. Disclosure of Interests None Declared.