Table 1. Differences between those patients interviewed and those who were not interviewed.

	Telephoned	Not telephoned
Variable	(N=570)	(N=321)	Statistic	Significance
Mean (s.d.) age in years	61.6 (11.8)	58.6 (14.1)	t=−3.312	P=0.001
Percentage (number) female	89.1 (508)	70.1 (225)	χ2 48.159	P<0.001
Mean (s.d.) total HAD score	19.2 (4.7)	19.6 (4.5)	t=1.57	P=0.117