Appendix.
Calculating the Cumulative Attributable Difference (CAD) Metric With 3 Different SIR Goals Among 3 Hypothetical Hospitals Participating in NHSN Catheter-Associated Urinary Tract Infections (CAUTI) Surveillance
| CAD | Equation | Hospital A | Hospital B | Hospital C |
|---|---|---|---|---|
| CAD = Observed–(Predicted*SIRgoal) | Observed no. = 6 (4 in ICUs, 2 in non-ICUs) Predicted no. = 2 (1 in ICUs, 1 in non-ICUs) SIR = 6/2 = 3.0 |
Observed no. = 20 (12 in ICUs, 8 in non-ICUs) Predicted no. = 10 (6 in ICUs, 4 in non-ICUs) SIR = 20/10 = 2.0 |
Observed no. = 8 (2 in ICUs, 6 in non-ICUs) Predicted no. = 10 (5 in ICUs, 5 in non-ICUs) SIR = 8/10 = 0.8 |
|
| I. CAD | ||||
| Number of CAUTIs that must be prevented given SIRgoal = 1.0 (the national baseline) |
CAD = Observed–(Predicted*SIRgoal ) | CAD = 6−(2 × 1.0) = 4 | CAD = 20−(10 × 1.0) = 10 | CAD = 8–(10 × 1.0) = −2 |
| Number of CAUTIs that must be prevented given SIRgoal = 1.057 (the 2013 national SIR) |
CAD = Observed–(Predicted*SIRgoal) | CAD = 6−(2 × 1.057) = 3.88 |
CAD = 20–(10 × 1.057) = 9.4 |
CAD = 8–(10 × 1.057) = − 2.6 |
| Number of CAUTIs that must be prevented given SIRgoal = 0.75 (the HHS target) |
CAD = Observed–(Predicted*SIRgoal) | CAD = 6–(2 × 0.75) = 4.5 | CAD = 20–(10 × 0.75) = 12.5 |
CAD = 8−(10 × 0.75) = 0.5 |
|
II. CAD, stratified by location type (ICU vs non-
ICU) |
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| Number of CAUTIs that must be prevented given SIRgoal = 1.18 (the 2013 national SIR in ICUs) and 0.8 (the 2013 national SIR in non-ICUs) |
CAD = [Observed – (Predicted*SIRgoal)]ICU + [Observed – (Predicted*SIRgoal)]non-ICU |
ICU
CAD ICU = 4−(1 × 1.2) = 2.8 |
ICU
CAD ICU = 12–(6 × 1.2) = 4.8 |
ICU
CAD ICU = 2–(5 × 1.2) = −4 |
|
Non-ICU
CAD non-ICU = 2–(1 × 0.8) = 1.2 CAD = 2.8 + 1.2 = 4.0 |
Non-ICU
CAD non-ICU = 8–(4×0.8) = 4.8 CAD = 4.8 + 4.8 = 9.6 |
Non-ICU
CAD non-ICU = 6–(5 × 0.8) = 2 CAD = − 4+2 = −2 |
NOTE. Although the Targeted Assessment for Prevention strategy may be implemented to achieve a chosen standardized infection ratio (SIR) goal, the ultimate goal should be aimed toward elimination of healthcare-associated infections. ICU, intensive care units; NHSN, National Healthcare Safety Network; non-ICU, non–intensive care units.