Table 5.

Results of logistic regression with manual backward selection procedure

	OR (95% CI)	p
Cardiovascular disease yes/no	3.07 (1.26–7.47)	0.01
Disease duration (years)	1.008 (1.001–1.016)	0.03
Frequency of attack (per year)	1.23 (1.07–1.42)	0.01
Creatinine clearance (ml/min)	2.03 (0.91–1.00)	0.10