Table 3

Stratification by covariates

Variable

Number of studies

Significant % reduction in VRE acquisition

Fisher's exact test comparing strata

Type of intervention

NS¹

Vancomycin reduction alone

6

2

Vancomycin plus other interventions

7

5

Site-based²

(p = 0.029, FET²)

Ward alone

7

6

Hospital-wide

6

1

VRE acquisition occurrence³

NS

Outbreak only

2

2

Endemic (with or without outbreak)

9

3

Study design

NS

A1

5

3

A1*

4

4

A2 ^†

5

2

Duration of intervention

NS

≤ 6 months

4

3

> 6 months

9

4

¹ NS = not significant result of Fisher's exact test comparing strata

² Stratification by severity of illness yields identical results to the site-based stratification: "ward alone" and "high severity of illness" are identical strata; "hospital wide" and moderate severity of illness" are identical strata

³Excluded Rubin et al. (initial cases) and Fridkin et al. (multi-cite, outbreak/endemic status not reported)

A1 = 1-group pretest-posttest design; A2 = 1-group pretest-posttest design that uses a double pre-test (for a complete description of hierarchy of quasi-experimental design studies, see Harris et al.), * Category A1 with multiple post-tests; ^† Category A2 with multiple post-tests

de Bruin and Riley BMC Infectious Diseases 2007 7:24   doi:10.1186/1471-2334-7-24