Table 2.

Crude and adjusted rate ratios from Cox regression analyses of determinants of therapy failure for antibiotic treatment of urinary tract infections

	Crude RR	95% CI	Adjusted* RR 95%	95% CI	Failure (%)
Characteristics at index date Age group (years)
15–24	1.0		1.0		13.5
25–34	0.99	0.88, 1.12	0.99	0.87, 1.11	13.3
35–44	0.99	0.85, 1.12	0.99	0.88, 1.13	13.3
45–54	1.16	1.03, 1.31	1.19†	1.05, 1.34	15.5
55–64	1.22	1.07, 1.39	1.26†	1.10, 1.43	16.2
Year start
1992–1993	1.0		1.0		12.4
1994–1996	1.19	1.07, 1.32	1.17†	1.05, 1.31	14.6
1997–1998	1.21	1.08, 1.36	1.22†	1.08, 1.37	14.9
Type of antibiotic and duration of therapy
Nitrofurantoin
3 days	1.0		1.0		18.9
5 days	0.67	0.57, 0.79	0.67†	0.57, 0.79	13.1
7 days	0.64	0.53, 0.77	0.63†	0.52, 0.75	12.5
Trimethoprim
3 days	0.82	0.71, 0.94	0.82†	0.72, 0.95	15.6
5 days	0.68	0.59, 0.79	0.69†	0.60, 0.80	13.2
7 days	0.71	0.58, 0.88	0.71†	0.58, 0.88	13.7
Norfloxacin
5 days	0.62	0.42, 0.92	0.60†	0.40, 0.89	12.3
7 days	0.43	0.31, 0.59	0.42†	0.30, 0.57	8.5
One year prior to start of antibiotic therapy Oral corticosteroids
No	1.0				14.2
Yes	1.08	0.86, 1.36			15.2
Hormone replacement therapy
No	1.0				14.1
Yes	1.04	0.92, 1.17			14.6
Antidiabetic therapy
No	1.0				14.2
Yes	0.86	0.66, 1.12			12.3
Oral contraceptives
No	1.0				14.5
Yes	0.94	0.87, 1.02			13.8
Hospitalization
No	1.0		1.0		13.9
Yes	1.28	1.12, 1.46	1.31†	1.15, 1.50	17.4

^*Variables significantly associated with therapy failure after antibiotic treatment (RR < > 1) were analysed in one multivariate model.

^†Significantly different from reference category. RR >1 indicates that the variable increases therapy failure after antibiotic therapy, while RR <1 indicates that the variable decreases therapy failure after antibiotic therapy.