Oral anticoagulants in the elderly.
Over a 1-year period, 34,998 prothrombin time tests were performed on 2,379 patients aged 40-89 years with a recommended target International Normalized Ratio (INR) value of 2.5. At least one INR value of >/= 5 was found in 507/2,379 patients (21.3%). The elderly demonstrated higher maximum and lower minimum INR values, lower warfarin doses, and an increased number of tests performed. After adjustment for these factors, the risk of INR values >/= 5 increased with age by 15% every 10 years (95% CI 4-28%). We conclude that age is a risk factor for more unstable prothrombin time results.
Froom
Paul
P
Central Laboratory, Haifa and Western Galilee, Clalit Health Services, Nesher, Israel. paulf@ioh.org.il
Miron
Ehud
E
Barak
Mira
M
D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000925:Anticoagulants / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D011517:Prothrombin Time; D012307:Risk Factors; D014859:Warfarin / Q000008:administration & dosage*
D000925:Anticoagulants; D014859:Warfarin