Non-vitamin K oral anticoagulants and risk of fractures: a systematic review and meta-analysis

Deficiency of protein C or protein S as a possible cause of osteoporosis

Proteins C and S are vitamin K-dependent anticoagulative factors that also exert a significant influence on bone quality. Clinical studies have linked the deficiency of proteins C and S to lower bone mineral density and the onset of femoral head osteonecrosis in children. Rare foundational studies analyzing this topic have demonstrated that activated protein C, upon binding to the endothelial protein C receptor expressed on the surface of osteoblasts, promotes osteoblast proliferation. It is also established that proteins C and S play crucial roles in proper collagen synthesis and in maintaining the number of osteoclasts and blood vessels. However, the association between protein C and/or S deficiency and the gradual onset of osteoporosis remains largely uninvestigated. Calculations based on data from peer-reviewed journals suggest that approximately one in every 10 individuals may develop osteoporosis due to congenital protein C or S deficiency. Moreover, when secondary causes of protein C and S deficiency are also considered, the proportion likely further increases. In this paper, we discuss the pathophysiological background of the potential relationship between protein C and S deficiency and the genesis of osteoporosis.

Evaluation of Fracture Risk Among Patients With Type 2 Diabetes and Nonvalvular Atrial Fibrillation Receiving Different Oral Anticoagulants

OBJECTIVE

Patients with type 2 diabetes are at higher risk for fracture risk because of attenuated bone turnover and impaired bone microarchitecture. The comparative effect of warfarin over non-vitamin K antagonist oral anticoagulants (NOACs) on incident fractures among patients with type 2 diabetes comorbid with atrial fibrillation (AF) remains to be elucidated.

RESEARCH DESIGN AND METHODS

This was a retrospective, propensity score-weighted, population-based cohort study of adults with type 2 diabetes and AF who were started on warfarin or NOAC between 2005 and 2019 identified from an electronic database of the Hong Kong Hospital Authority. The primary outcome was a composite of major osteoporotic fractures (hip, clinical vertebral, proximal humerus, and wrist). Hazard ratios (HRs) were calculated using Cox proportional hazards regression models.

RESULTS

A total of 15,770 patients with type 2 diabetes comorbid with AF were included (9,288 on NOAC, 6,482 on warfarin). During a median follow-up of 20 months, 551 patients (3.5%) sustained major osteoporotic fractures (201 [2.2%] in the NOAC group, 350 [5.4%] in the warfarin group). The adjusted cumulative incidence was lower among NOAC users than warfarin users (HR 0.80; 95% CI 0.64, 0.99; P = 0.044). Subgroup analyses showed consistent protective effects against major osteoporotic fractures among NOAC users across sex, age, HbA1c, duration of diabetes, and history of severe hypoglycemia compared with warfarin users.

CONCLUSIONS

NOAC use was associated with a lower risk of major osteoporotic fractures than warfarin use among patients with type 2 diabetes comorbid with AF. NOAC may be the preferred anticoagulant from the perspective of bone health.

The association of non-vitamin K antagonist oral anticoagulants vs. warfarin and the risk of fractures for patients with atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

The fracture risks of non-vitamin K antagonist oral anticoagulants (NOACs) vs. warfarin in patients with atrial fibrillation (AF) remain controversial.

METHODS

PubMed, Cochrane Library, EMBASE, Clinical Trials.gov databases for RCTs, and cohort studies were systematically searched from inception to 10 June 2021.

RESULTS

Twelve-two studies met the inclusion criteria and 477,821 patients were included. Warfarin increased the risk of fracture in AF patients compared with NOACs in overall any fracture (RR = 0.79; 95% CI = 0.70-10.88; p = 0.00), osteoporotic fracture (RR = 0.746; 95% CI = 0.630-0.883; p = 0.001). No significant difference was observed in the hip or pelvic fracture, vertebral fracture, extremity fracture, wrist fracture, femoral neck fracture, and ankle fracture. In subgroup analyses based on several aspects, NOACs were associated with a significant reduction in any fracture (standard dosage NOACs, cohort studies, elderly patients, rivaroxaban in RCTs, dabigatran, rivaroxaban, and apixaban in cohort studies), in the hip/pelvic fracture (follow-up time ≤1 year, cohort studies), and osteoporotic fracture (cohort studies).

CONCLUSION

NOACs were associated with a significantly lower risk of any fracture and osteoporotic fracture compared to warfarin. This benefit was also observed in specific NOACs types of dabigatran, rivaroxaban, and apixaban. However, whether NOACs had a less fracture risk than warfarin on the other risk of fractures was still uncertain.

Hip fractures risks in edoxaban versus warfarin users: A propensity score-matched population-based cohort study with competing risk analyses

OBJECTIVE

The three direct oral anticoagulants (DOAC), rivaroxaban, apixaban and dabigatran have been associated with lower risks of fractures compared to warfarin. However, no large scale studies have explored the associations with the newest DOAC, edoxaban, with fracture risk. The present study aims to elucidate the effects of edoxaban on the risk of hip fracture amongst elderly patients by comparing the incidence of new onset hip fracture between edoxaban and warfarin users in a Chinese population.

METHODS

This was a retrospective population-based cohort study of patients with edoxaban or warfarin use between January 1st, 2016 and December 31st, 2019 in Hong Kong, China. Patients with less than one-month exposure, medication switching between warfarin and edoxaban, those who died within 30 days after drug exposure, prior human immunodeficiency virus infection, age <50 years old, and those with prior hip fractures were excluded. Propensity score matching (1:2) between edoxaban and warfarin users using the nearest neighbour method was performed based on demographics, prior comorbidities, and use of different medications. The study outcomes were new onset hip fractures, medically attended falls and all-cause mortality.

RESULTS

A total of 5014 patients including 579 edoxaban users and 4435 warfarin users (median age: 70 years old [interquartile range (IQR): 62-79], 56.66% males) with a median follow-up of 637.5 (IQR: 320-1073) days were included. In the matched cohort, edoxaban users had significantly lower rates of new onset hip fractures, medically attended falls and all-cause mortality. The protective value of edoxaban use against new onset hip fracture (hazard ratio [HR]: 0.13, 95% confidence interval [CI]: [0.03-0.54], p = 0.0051), medically attended falls (HR: 0.47, [0.29-0.75], p = 0.0018) and all-cause mortality (HR: 0.61, [0.42-0.87], p = 0.0059) in comparison to warfarin use persisted after matching. The significant relationship between edoxaban use and lower fracture risk was preserved in all sensitivity analyses using different approaches using the propensity score.

CONCLUSIONS

Edoxaban use is associated with lower risks of new onset hip fractures, medically attended falls and mortality risks compared to warfarin after propensity score matching.

Bone density and quality in patients treated with direct-acting oral anticoagulants versus warfarin

INTRODUCTION

Direct-acting oral anticoagulants (DOACs) are therapeutic alternatives to warfarin that act independently of vitamin K, thus not affecting bone matrix formation. The aim of this study was to compare bone mineral density (BMD) and microarchitecture in patients treated with DOACs versus warfarin.

METHODS

Cross-sectional, observational study in patients using oral anticoagulants for >1 year and a paired control group (CG). Based on the type of anticoagulant used, the patients were grouped into a DOAC (DOACG) or warfarin (WG) group. All patients filled out a questionnaire and underwent BMD evaluation and trabecular bone score (TBS) measurement.

RESULTS

In all, 150 patients were included (50 patients in each group). The mean age was 60.49 ± 7.48 years, and most participants were men (64%). The most frequent comorbidities were hypertension, dyslipidemia, and hyperglycemia (comparison between groups p > 0.05). Low bone mass was diagnosed in 42%, 50%, and 66% of the patients in the CG, DOACG, and WG, respectively (p = 0.012). On logistic regression analysis, BMD was associated with body mass index (BMI; odds ratio [OR] 0.846, 95% confidence interval [CI] 0.763-0.926, p = 0.001), creatinine level (OR 0.024, 95%CI 0.001-0.434, p = 0.017), and TBS value (OR 17.777, 95%CI 4.526-96.903, p = 0.000). The mean TBS decreased progressively from the CG to the DOACG and WG (1.328 ± 0.112, 1.264 ± 0.138, and 1.203 ± 0.112, respectively, p < 0.001). On multivariate linear regression, negative predictors of TBS included warfarin use (-0.06, 95%CI -0.11 to -0.02, p = 0.006), BMI (-0.01, 95%CI -0.01 to -0.00, p < 0.001), and hyperglycemia (-0.07, 95%CI -0.11 to -0.03, p = 0.003), while positive predictors were an active IPAQ classification (0.06, 95%CI 0.01-0.11, p = 0.029) and family history of hip fracture (0.07, 95%CI 0.01-0.14, p = 0.029).

CONCLUSION

Patients using anticoagulants have lower BMD and TBS values compared with controls. This negative effect on bone was more pronounced with warfarin, but was also seen with DOACs.