Table 3.

Performance of gene-based warfarin dosing algorithms alone and with race or number of concurrent medications added as covariates

Algorithm	Original algorithm		Race added*		No. of concurrent medications added
	R2	Adj. R2	Δ adj. R2	P value race	Δ adj. R2	P value medications
Wu 2008 [31]	0.55	0.50	–	–	0	0.67
Gage 2008 [30]	0.54	0.51	–	–	0	0.46
Anderson 2007 [27]	0.52	0.50	0.01	0.11	0.01	0.43
Herman 2006 [34]	0.52	0.50	0	0.19	0	0.36
Zhu 2007 [29]	0.51	0.49	0.01	0.11	0	0.34
IWPC 2009 [33]	0.50	0.45	–	–	0	0.80
Tham 2006 [26]	0.48	0.46	−0.01	0.78	0	0.63
Wadelius 2009 [32]	0.46	0.43	0	0.26	0.01	0.96
Wadelius 2005 [24]	0.46	0.42	0.01	0.29	0	0.78
Sconce 2005 [23]	0.45	0.44	0	0.22	−0.01	0.71
Takahashi 2006 [25]	0.38	0.35	0	0.65	0	0.87
Miao 2007 [28]	0.37	0.35	−0.01	0.70	0.01	0.76

^*Wu et al. 2008 [31], Gage et al. 2008 [30], and IWPC 2009 [33] include indicators for race.

Adj., adjusted; IWPC, International Warfarin Pharmacogenetics Consortium.