• Wallis C Y Lau, Esther W Chan, Ching-Lung Cheung, Chor Wing Sing, Kenneth K C Man, Gregory Y H Lip, Chung-Wah Siu, Joanne K Y Lam, Alan C H Lee, and Ian C K Wong.
• Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
• JAMA. 2017 Mar 21; 317 (11): 1151-1158.

ImportanceThe risk of osteoporotic fracture with dabigatran use in patients with nonvalvular atrial fibrillation (NVAF) is unknown.ObjectiveTo investigate the risk of osteoporotic fracture with dabigatran vs warfarin in patients with NVAF.Design, Setting, And ParticipantsRetrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly diagnosed with NVAF from 2010 through 2014 and prescribed dabigatran or warfarin were matched by propensity score at a 1:2 ratio with follow-up until July 31, 2016.ExposuresDabigatran or warfarin use during the study period.Main Outcomes And MeasuresRisk of osteoporotic hip fracture and vertebral fracture was compared between dabigatran and warfarin users using Poisson regression. The corresponding incidence rate ratio (IRR) and absolute risk difference (ARD) with 95% CIs were calculated.ResultsAmong 51 496 patients newly diagnosed with NVAF, 8152 new users of dabigatran (n = 3268) and warfarin (n = 4884) were matched by propensity score (50% women; mean [SD] age, 74 [11] years). Osteoporotic fracture developed in 104 (1.3%) patients during follow-up (32 dabigatran users [1.0%]; 72 warfarin users [1.5%]). Results of Poisson regression analysis showed that dabigatran use was associated with a significantly lower risk of osteoporotic fracture compared with warfarin (0.7 vs 1.1 per 100 person-years; ARD per 100 person-years, -0.68 [95% CI, -0.38 to -0.86]; IRR, 0.38 [95% CI, 0.22 to 0.66]). The association with lower risk was statistically significant in patients with a history of falls, fractures, or both (dabigatran vs warfarin, 1.6 vs 3.6 per 100 person-years; ARD per 100 person-years, -3.15 [95% CI, -2.40 to -3.45]; IRR, 0.12 [95% CI, 0.04 to 0.33]), but not in those without a history (0.6 vs 0.7 per 100 person-years; ARD per 100 person-years, -0.04 [95% CI, 0.67 to -0.39]; IRR, 0.95 [95% CI, 0.45 to 1.96]) (P value for interaction, <.001).Conclusions And RelevanceAmong adults with NVAF receiving anticoagulation, the use of dabigatran compared with warfarin was associated with a lower risk of osteoporotic fracture. Additional study, perhaps including randomized clinical trials, may be warranted to further understand the relationship between use of dabigatran vs warfarin and risk of fracture.

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