[Anti-factor Xa activity of enoxaparin for thromboprophylaxis in nonsurgical patients is dependent on body mass].
OBJECTIVE
Thromboprophylaxis with a fixed dose of low-molecular-weight heparin is recommended for hospitalized acutely ill medical patients. The purpose of this study was to assess whether the anti-factor Xa (anti-Xa) activity of enoxaparin prescribed for venous thromboembolism prophylaxis depends on body mass index (BMI) in patients hospitalized for an acute respiratory disease.


METHODS
All patients admitted to the respiratory medicine department (January-December 2006) for an acute respiratory disease, and for whom pharmacologic thromboprophylaxis was indicated, were included in the study. Anti-Xa activity was measured 4 hours after administration of enoxaparin on the third day of hospitalization. The primary outcome was anti-Xa activity in relation to BMI.


RESULTS
One hundred twelve patients were enrolled. Mean anti-Xa activity decreased with each BMI quartile (0.28, 0.23, 0.15, and 0.13 U/mL for quartiles 1, 2, 3, and 4, respectively). In the multivariate analysis, BMI was the only predictor of inadequate anti-Xa activity (odds ratio, 1.14; 95% confidence interval, 10.5-1.24; P< .002) after adjustment for age, sex, and serum creatinine levels. Two episodes of symptomatic proximal deep vein thrombosis were diagnosed in the month after hospitalization; both occurred in patients who had inadequate anti-Xa activity.


CONCLUSIONS
Anti-Xa activity is dependent on BMI in hospitalized acute medical patients receiving enoxaparin for thromboprophylaxis.
Jiménez
David
D
Servicio de Neumología. Hospital Ramón y Cajal. Madrid. España. djc_69_98@yahoo.com
Díaz
Gema
G
Iglesias
Ana
A
César
Jesús
J
García-Avello
Angel
A
Martí
David
D
Escobar
Carlos
C
Vidal
Rafael
R
Sueiro
Antonio
A
D000368:Aged; D015992:Body Mass Index; D017984:Enoxaparin / Q000627:therapeutic use*; D015951:Factor Xa / Q000276:immunology*; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006760:Hospitalization; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013997:Time Factors; D054556:Venous Thromboembolism / Q000276:immunology* / Q000517:prevention & control* / Q000534:rehabilitation
D017984:Enoxaparin; D005343:Fibrinolytic Agents; D015951:Factor Xa