OBJECTIVE To determine the prevalence of acetylsalicylic acid therapy
and effect of the drug on hemoglobin concentration over time. DESIGN R
etrospective, observational study. SETTING Primary care population in
a university-affiliated family medicine clinic. PATIENTS A population-
based sample of 80 patients receiving low-dose ASA for secondary preve
ntion of cardiovascular disease was studied. Of 84 patients receiving
the drug after a cardiovascular problem, four were excluded: one man d
ied of a recurrent stroke during the study; the file of a second man w
as unavailable; another man developed a bleeding ulcer; and one woman
had been taking ASA for only 1 month when the data were collated. MAIN
OUTCOME MEASURES Demographic variables of patients taking low-dose AS
A, duration of ASA use, and two successive measures of hemoglobin leve
l. RESULTS The frequency of ASA administration was 7.7% for men aged 6
0 and older and 2.9% for women. Women had no significant change in hem
oglobin level, while men had a mean loss of 0.472 g/dL (95 % confidenc
e interval, .198 to .746; P=.009). For the study population as a whole
(80 patients), the average decline was 0.294 g/dL (95% confidence int
erval,.039 to .549; P=.029). CONCLUSIONS Although the clinical signifi
cance of these findings is uncertain, they suggest the need for a pros
pective investigation of the influence of low-dose ASA on hemoglobin l
evels.