Table 1.

 Patient demographics and international normalised ratio (INR) tests

Age group (years)	n	Mean age (years)	Men	INR tests			INR control
				Mean INR	Number/ patient/year	Dosing interval (days)	<2.0	>3.0	<2.0 or >3.0
<65	149	56.4 (7.8)	67.1%	2.4 (0.3)	17.4 (5.1)	21.0 (2.6)	25.3%	12.7%	37.9%
65–75	284	69.8 (2.7)	63.0%	2.4 (0.2)	36.8 (6.7)	9.9 (2.2)	22.2%	14.2%	36.4%
>75	306	80.3 (2.8)	45.4%	2.5 (0.3)	45.7 (6.0)	8.1 (6.9)	22.3%	15.4%	37.7%

Data are mean (SD) or percentage.

Number of INR tests increased significantly with age: <65 v 65–75 years (p<0.01) and 65–75 v >75 years (p<0.01). Correspondingly, the interval between tests shortened significantly with increasing age: <65 v 65–75 years (p<0.01) and 65–75 v >75 years (p<0.01). No significant between group differences were observed with respect to INR control.