Table 2

Proportion of patient time (95 % confidence intervals) within International Normalized Ratio (INR) ranges for randomly selected patients started on, and established on, warfarin treatment for chronic atrial fibrillation. The standard INR range is 2.0 to 3.0, but there were some individual ranges.

Started on warfarin (N = 25)

Established on warfarin (N = 24)

Treatment intervals (INR)

1st month

2nd month

3rd month


Super therapeutic (>3.0)

17.0 (7.9–26.1)

14.4 (6.6–22.2)

9.9 (1.3–18.5)

18.8 (8.0–29.7)

Therapeutic (2.0 – 3.0)

54.2 (42.1–66.4)

66.9 (54.3–79.7)

75.4 (61.1–89.8)

70.2 (59.9–80.4)

Sub therapeutic (<2.0)

28.7 (15.8–41.5)

18.6 (6.7–30.5)

14.6 (2.3–27.0)

11.0 (4.2–17.8)


Nilsson and Björholt BMC Clinical Pharmacology 2004 4:1   doi:10.1186/1472-6904-4-1

Open Data