Safety profile of tinzaparin administered once daily at a standard curative dose in two hundred very elderly patients

Objectives: Too few very elderly patients with an age-related renal impairment are included in clinical trials. We conducted a study in order to evaluate the safety profile of tinzaparin, a low molecular weight heparin (LMWH), given at a curative dose (175 IU/kg once daily) in very elderly patients treated for up to 30 days. Setting: An 800-bed geriatric hospital. Design: A 1-year prescribing study. Patients: Consecutive in-patients older than age 70, whose creatinine clearance was above 20 ml/min, and requiring full anticoagulation with LMWH were included. Measurements: Safety parameters (major bleeding/heparin-induced thrombocytopenia/death) were recorded. Plasma anti-Xa activity levels were regularly measured throughout the treatment period. Results: Two-hundred in-patients, mean age 85.2 +/- 6.9 years (70 to 102), mean creatinine clearance 51.2 +/- 22.9 ml/min, were given tinzaparin. Six patients died during the treatment period: only one could be related to the anticoagulation treatment. Three major bleeding episodes (1.5%) were reported. Antithrombotic drug interactions likely contributed to the bleeding event in two of them. Heparin-induced thrombocytopenia was confirmed in two patients (1%). No correlation was found between anti-Xa activity and creatinine clearance or age. Conclusions: Tinzaparin can be used safely at a curative dose in very elderly patients as long as (i) the accurate bodyweight-adjusted dose is given; (ii) platelet counts and anti-Xa levels are regularly monitored and; (iii) the interaction with other antithrombotic drugs is correctly managed.