Introduction: Renal impairment (RI) may induce an inflammatory/procoagulant state as well as platelet dysfunction. Little is known on the prevalence of RI and long-term prognosis of older patients with venous thromboembolism (VTE) who have concomitant RI.

Methods: In a prospective multicenter cohort, we analyzed 912 patients aged ≥65 years with acute VTE. Using the CKD-EPI formula, we defined three categories of baseline renal function: estimated glomerular filtration rate ≥60 ml/min/1.73m²(no RI), 30-59 ml/min/1.73m²(moderate RI), and <30 ml/min/1.73m²(severe RI). The outcomes were VTE recurrence, major bleeding, and overall mortality. We examined the association between renal function and clinical outcomes using competing risk regression models, adjusting for relevant confounders and periods of anticoagulation.

Results: We followed 912 patients over a median duration of 29.6 months. Overall, 313 (34%) patients had moderate and 51 (6%) severe RI. One hundred and seven patients (12%) had VTE recurrence, 125 (14%) had major bleeding, and 186 (20%) died during follow-up. After adjustment, severe RI was associated with a 2-fold increased risk of major bleeding (sub-hazard ratio [SHR] 2.1, 95% CI 1.1-4.0) compared to no RI, but not with VTE recurrence (SHR 0.6, 95% CI 0.2-1.8) or overall mortality (hazard ratio 1.0, 95% CI 0.6-1.9). Moderate RI was not significantly associated with adverse clinical outcomes.

Conclusions: RI was common among older patients with acute VTE. Severe RI was associated with a 2-fold increased long-term risk of major bleeding, without a risk increase in terms of VTE recurrence and overall mortality. Older patients with moderate RI did not carry worse prognosis.