A self-controlled case series to assess the effectiveness of beta blockers for heart failure in reducing hospitalisations in the elderly

Table 1 Characteristics of study subjects by period of observation

Exposure Status	Number of Subjects	Follow-up Years*	Duration of exposure*	Age at first hospitalisation*	Age at first exposure*
1 Year observation period
Exposed	645	0.5(0.3,0.7)	0.3(0.1,0.6)	81(79,84)	81(78,84)
Unexposed	2805	0.5(0.3,0.8)		82(79,86)
4 Year observation period
Exposed	3276	2.0(1.1,3.0)	0.8(0.2,1.8)	83(80,86)	81(78,84)
Unexposed	9406	1.7(1.0,3.0)		83(80,87)

ISSN: 1471-2288