Table 3.

Clinical covariates associated with steady-state warfarin dose.

	Median ratio (95% CI)	R2	p-value
Age (per 10-year change)	0.945 (0.938–0.953)	0.154	3.02 × 10-44
Height (per 10-cm change)	1.042 (1.030–1.054)	0.042	3.34 × 10-12
Weight (per 5-kg change)	1.015 (1.012–1.017)	0.105	7.12 × 10-30
BMI (per 5-kg/m2 change)	1.036 (1.028–1.044)	0.061	4.92 × 10-17
Body surface area (per 0.2 m2 change)	1.048 (1.040–1.056)	0.112	6.23 × 10-31
Female gender	0.946 (0.922–0.971)	0.015	2.23 × 10-5
African–American race	1.088 (1.051–1.125)	0.018	4.13 × 10-6
Current smokers	1.072 (1.033–1.111)	0.011	3.40 × 10-4
Amiodarone use	0.856 (0.811–0.902)	0.032	5.73 × 10-10
Enzyme-inducer use	1.016 (0.939–1.093)	0.000	0.684
Indication
Venous thromboembolism	1.076 (1.048–1.103)	0.024	9.68 × 10-8
Atrial fibrillation	0.912 (0.888–0.936)	0.041	2.24 × 10-12
Stroke	1.003 (0.950–1.056)	0.000	0.912
Orthopedic	1.142 (0.897–1.387)	0.001	0.255

Effect sizes (represented as median ratios with 95% CI and R²) and p-values are given for each test of association. The median ratio is the exponentiated parameter estimate from the linear regression model of the log-transformed warfarin dose. To aid in interpreting the results in the table, for example, a 10-year increase in age is associated with a 5.5% decrease in the median weekly warfarin dose.