Improving the Measurement of Surgical Site Infection Risk Stratification/Outcome Detection

Exhibits 53 to 55

Exhibit 53. Results of logistic regression using the 60% derivation set, including each of the five surgical procedures as a possible risk factor

Variable Estimate tValue Probability
Intercept -5.47 -4.82 0.0000
Emergency surgery 0.74 3.05 0.0023
Chronic kidney disease -1.84 -2.49 0.0130
Male 0.0130 2.37 0.0180
History of MRSA 1.50 4.74 0.0000
No. of surgeons* 0.79 2.39 0.0168
Postop admission 2.58 9.73 0.0000
Preop glucose* 0.00 0.55 0.5893
Preop hemoglobin -0.24 -4.04 0.0001
Preop stay 0.02 0.82 0.4096
Surgery duration 0.00 1.61 0.1073
Herniorrhaphy 0.88 2.90 0.0037

* Additional Intermountain risk factor.

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Exhibit 54. Results of logistic regression using the 40% validation set, and including each of the five surgical procedures as a possible risk factor

Variable Estimate tValue Probability
Intercept -4.97 -3.66 0.0003
Emergency surgery 0.01 0.04 0.9686
Chronic kidney disease -1.54 -2.05 0.0400
Male 0.13 0.60 0.5510
History of MRSA 1.12 3.10 0.0020
No. of surgeons* 0.83 1.82 0.0695
Postop admission 1.95 8.07 0.0000
Preop glucose* 0.00 -1.00 0.3223
Preop hemoglobin -0.17 -2.62 0.0090
Preop stay 0.04 1.13 0.2574
Surgery duration 0.00 3.07 0.0021
Herniorrhaphy 0.84 2.76 0.0059

* Additional Intermountain risk factor.

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Exhibit 55. Results of logistic regression using the combined derivation and validation sets and including each of the five surgical procedures as a possible risk factor

Variable Estimate tValue Probability
Intercept -5.41 -6.37 0.0000
Elective surgery 0.42 0.42 0.0246
Chronic kidney disease -1.68 -3.20 0.0014
Male 0.31 1.99 0.0469
History of MRSA 1.35 5.70 0.0000
No. of surgeons* 0.80 3.05 0.0023
Postop admission 0.0023 12.74 0.0000
Preop glucose* 0.00 -0.27 0.7842
Preop hemoglobin -0.19 -4.23 0.0000
Preop stay 0.04 1.51 0.1308
Surgery duration 0.00 3.42 0.0006
Herniorrhaphy 0.86 4.02 0.0001

* Additional Intermountain risk factor.

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Page last reviewed December 2012
Internet Citation: Exhibits 53 to 55. Content last reviewed December 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/ssi/ssiexh53-55.html