Bleeding Events and Correlation with Anti-Xa Levels and Therapeutic Nadroparin Dose in Patients with Impaired Renal Function

Dutch national guidelines for therapeutic treatment with low-molecular-weight heparins (LWMHs) in patients with renal insufficiency recommend dose adjustment based on observed anti-Xa levels. The literature on the relationship between anti-Xa levels and clinical outcome in terms of bleeding events is inconsistent. The primary aim of this study was to investigate the incidence and correlation of bleeding events in relation to anti-Xa levels in patients with impaired renal function, using therapeutic nadroparin according to the national guidelines. The secondary objective was to investigate the correlation between the LMWH dose and bleeding events. This was a retrospective study of patients with impaired renal function treated with therapeutic nadroparin for which anti-Xa levels were monitored. Bleeding and thrombotic events were assessed for each patient. This study included 243 patients, of whom 61 (25%) had a bleeding event. There was no correlation between anti-Xa levels and the occurrence of bleeding. Although there was no difference in renal function, weight, or body mass index (BMI) between patients with or without a bleeding event, the median dose of nadroparin was significantly higher (p < 0.005) in patients with a bleeding event. In conclusion, for this study population, there was a high incidence of bleeding. No correlation was found between anti-Xa levels and the occurrence of a bleeding event, with the majority of anti-Xa levels being subtherapeutic. However, a correlation was found between the dose and the occurrence of a bleeding event. Therefore, it is questionable whether the focus on monitoring anti-Xa levels is a justified method to reduce the risk of a bleeding event.