Older age is risk for an international normalized ratio (INR) of 5 or more.
The elderly have higher INR values, but this may be due to factors such as inter-current illnesses or drug changes. In the following case-controlled study we contacted 304 patients receiving warfarin treatment, one group with an INR of 5 or more, and three control groups (INR < 2, 2-3.9, 4-4.9). Variables that significantly predicted an INR of 5 or more in a logistic regression model included age, the use of antibiotics, stopping of a chronic drug, and the lack of knowledge of the target INR. After forcing in other variables associated with age (less valve disease, more use of multivitamins, and a lower dose of warfarin) the increased risk was 1.6 (1.12-2.28) per 10 years of age. We conclude that age is an independent risk factor for INR values of 5 or more.
Ribak
G
G
Sackler Medical School, Tel Aviv University, Tel Aviv, Israel.
Barak
M
M
Froom
P
P
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000494:pharmacology*; D016022:Case-Control Studies; D006487:Hemostasis / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D019934:International Normalized Ratio; D014859:Warfarin / Q000494:pharmacology*
D000925:Anticoagulants; D014859:Warfarin