Reduction of mortality in general medical in-patients by low-dose heparin prophylaxis.

The effect of prophylactic low-dose heparin on mortality was tested in 1358 consecutive patients admitted to the medical wards of an acute care hospital. Eligibility for treatment or exclusion was ascertained on admission by predefined contraindications. Eligible patients with even-number hospital records were assigned to treatment (5000 U twice daily), those with odd-number records served as controls. Because determination of eligibility was open to bias, evaluation of treatment was based on comparison of the total even-number group (669 patients, of which 411 were treated with heparin), and the total odd-number group (689 patients, none treated with heparin). Mortality was significantly lower in the even-number group-7.8% (52 of 669 patients) versus 10.9% (75 of 689 patients) in the odd-number group; the difference increased consistently with length of hospitalization (p = 0.025). The estimated reduction in mortality attributable to heparin was 31.1%. We believe that low-dose heparin prophylaxis is appropriate in all immobilized medical patients who are not at risk of bleeding.