Table 1.

 Multicentre ISI calibration of rTF/95 against RBT/90 reported by Tripodi and colleagues³

Centre	N	ISI	CV(b)	Slope of patients only line	INR (RBT/90)	INR (rTF/95)
1	73	0.85	2.8	0.80	2.94	3.22
2	72	0.97	4.0	1.06	2.75	2.67
3	78	0.99	1.8	1.12	2.79	2.70
4	75	0.94	3.3	0.87	2.78	2.77
5	78	0.95	2.4	0.94	2.59	2.54
6	79	0.96	2.1	0.99	2.74	2.71
7	69	0.92	3.3	1.02	2.66	2.77
8	80	0.88	2.8	0.92	2.43	2.58
9	80	0.94	3.4	0.95	2.72	2.74
10	72	0.93	2.2	0.95	2.86	2.83
11	67	1.05	3.5	1.04	2.56	2.31
12	78	0.90	2.7	0.94	2.62	2.79
13	79	0.94	2.7	0.92	2.43	2.44
14	73	0.98	2.0	1.03	2.75	2.71
15	75	0.95	2.3	1.02	2.87	2.89
16	74	0.92	3.5	0.93	2.41	2.45
17	68	0.96	2.2	0.92	2.90	2.77
18	74	0.87	2.8	0.93	2.40	2.58
19	79	0.99	2.5	1.08	2.62	2.53
Overall		0.94	2.8	0.97	2.67	2.68
CV (%)		5.0		7.9

N is the total number of samples used in each calibration. CV(b) is the coefficient of variation of the calibration slope for healthy subjects plus patients. The mean INR for the patients’ samples included in the calibration was calculated from RBT/90 and rTF/95 measurements. The bottom row gives the between centre CV of the ISI and slope of patients only line.

CV, coefficient of variation; INR, international normalised ratio; ISI, international sensitivity index.