Elderly Medical Patients Treated with Prophylactic Dosages of Enoxaparin: Influence of Renal Function on Anti-Xa Activity Level

Authors: Mahe, Isabelle¹; Gouin-Thibault, Isabelle²; Drouet, Ludovic³; Simoneau, Guy¹; Di Castillo, Heidi¹; Siguret, Virginie²; Bergmann, Jean-François¹; Pautas, Eric⁴

Source: Drugs & Aging, Volume 24, Number 1, 2007 , pp. 63-71(9)

Publisher: Adis International

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Abstract:

Background: The safety and optimal use of prophylactic treatment with low-molecular-weight heparins in elderly patients with impaired renal function remain undefined.

Methods: The primary aim of this study was to analyse, in `real life', the influence of renal function, as assessed by creatinine clearance (CL_CR), on the level of anti-Xa activity in medical hospitalised elderly patients receiving prophylactic dosages of enoxaparin. Consecutive hospitalised acutely ill medical patients aged ≥75 years receiving daily dosages of enoxaparin 4000IU for up to 10 days were prospectively enrolled in two centres. Peak anti-Xa activity was measured at the beginning and during the course of therapy.

Results: One hundred and twenty-five patients (31 men, 94 women), mean age 87.5 ± 6.3 years, mean bodyweight 56.4 ± 11.9kg and mean CL_CR 39.8 ± 16.1 mL/min, were enrolled in the study. The mean maximum anti-Xa activity (day 1 to day 10) [anti-Xa_max1-10] was 0.64 ± 0.23 IU/mL (range 0.24-1.50 IU/mL). Weak negative correlations were found between CL_CR and anti-Xa_max and between bodyweight and anti-Xa_max. Mean anti-Xa_max was slightly but significantly higher in patients with CL_CR of 20-30 mL/min compared with patients with CL_CR of 31-40, 41-50 or 51-80 mL/min (0.72 versus 0.61, 0.61 and 0.60 IU/mL, respectively), and in patients weighing <50kg compared with patients weighing 50-60kg or >60kg (0.74 vs 0.64 and 0.52 IU/mL, respectively). Serious bleeding occurred in five patients, but anti-Xa_max values in these patients were not different to those in patients without bleeding (p = 0.77). Individual anti-Xa_max at the beginning or during the course of treatment was measured in the subgroup of 58 patients in whom anti-Xa activity was measured at least once during the study. The mean anti-Xa_max value was slightly but significantly higher during the course of the therapy than at the beginning of the study (0.63 ± 0.26 IU/mL vs 0.56 ± 0.23 IU/mL, p = 0.012).

Conclusion: Only CL_CR <30 mL/min and bodyweight <50kg were associated with significantly higher anti-Xa_max values. The clinical relevance of these increases remains questionable. No conclusions about the safety of enoxaparin in elderly medical patients can be drawn from these findings.

Keywords: Elderly; Enoxaparin sodium; Low molecular weight heparins

Document Type: Research article

Affiliations: 1: 1 Internal Medicine Department A, Lariboisière Hospital, Paris, France 2: 2 Hematology Laboratory, Charles Foix Hospital, Ivry sur Seine, France 3: 3 Hematology Laboratory, Lariboisière Hospital, Paris, France 4: 4 Geriatric Department, Charles Foix Hospital, Ivry sur Seine, France

Publication date: 2007-01-01

Elderly Medical Patients Treated with Prophylactic Dosages of Enoxaparin: Influence of Renal Function on Anti-Xa Activity Level

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