Association between duration of anticoagulant thromboprophylaxis and revision rate in primary total hip arthroplasty: a Danish and Norwegian nationwide cohort study.

Background and purpose: There are concerns that bleeding following primary total hip arthroplasty (THA) contributes to prolonged wound drainage and prosthetic joint infection (PJI). We examined whether short (1-5 days), medium (6-14 days), and extended (≥ 15 days) duration of thromboprophylaxis is associated with the 5-year revision rate after THA due to osteoarthritis.

Patients and methods: We performed a cohort study based on data from hip arthroplasty and administrative registries in Denmark and Norway (2008-2014). The outcome was revision surgery due to PJI, aseptic loosening or any cause, and patient mortality. Adjusted cause-specific hazard ratios (HRs) were analyzed with Cox regression analyses.

Results: Among 50,482 THA patients, 8,333 received short, 17,009 received medium, and 25,140 received extended thromboprophylaxis. The HRs for revision due to PJI within 5 years were 1.0 (95%CI 0.7-1.3) and 1.1 (CI 0.9-1.3) for short and extended vs. medium treatment, whereas HR for extended vs. medium prophylaxis was 1.5 (CI 1.2-2.0) within 3 months. The HRs for revision due to aseptic loosening within 5 years were 1.0 (CI 0.7-1.4) and 1.1 (CI 0.9-1.4) for short and extended vs. medium treatment. The HRs for any revision within 5 years were 0.9 (CI 0.8-1.1) and 0.9 (CI 0.8-1.0) for short and extended vs. medium treatment. Extended vs. medium prophylaxis was associated with a decreased 0-3 month mortality. The absolute differences at 5 years were ≤ 1%.

Conclusion: Our data suggests no association between duration of anticoagulant thromboprophylaxis and revision rate within 5 years of primary THA. The extended thromboprophylaxis might be associated with early increased revision rate due to PJI but also with lower mortality; however, the clinical relevance of this finding requires further research.