Association of pharmacologic thromboprophylaxis with clinically relevant bleeding and hospital-acquired anemia in medical inpatients: the risk stratification for hospital-acquired venous thromboembolism in medical patients study

Background Pharmacologic thromboprophylaxis (pTPX) might exacerbate the risk of clinically relevant bleeding (CRB) and hospital-acquired anemia (HAA) in older multimorbid inpatients. Objectives We aimed to evaluate the association of pTPX use with CRB and HAA. Methods We used data from a prospective cohort study conducted in 3 Swiss university hospitals. Adult patients admitted to internal medicine wards with no therapeutic anticoagulation were included. pTPX use was ascertained during hospitalization. Outcomes were in-hospital CRB and HAA. We calculated incidence rates by status of pTPX. We assessed the association of pTPX with CRB using survival analysis and with HAA using logistic regression, adjusted for infection, length of stay, and the International Medical Prevention Registry on Venous Thromboembolism bleeding risk score. Results Among 1305 patients (mean age, 63.7 years; 44% women, 90% at low risk of bleeding), 809 (62%) received pTPX. The incidence of CRB was 2.4 per 1000 patient-days and was not significantly higher in patients with pTPX than in those without. We found no significant association between pTPX and CRB. HAA was frequent (20.2%) and higher in patients with pTPX than in those without (23.2% vs 15.3%). The incidence of HAA was 21.2 per 1000 patient-days and did not significantly differ between patients with pTPX and those without. We found an association between pTPX and HAA (adjusted odds ratio, 1.4; 95% CI, 1.0-2.1). Conclusion Our study confirmed the safety of pTPX in medical inpatients at low risk of bleeding but identified an association between pTPX and HAA. Adherence to guidelines that recommend administering pTPX to medical inpatients at increased venous thromboembolism risk and low bleeding risk is necessary.