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

Exhibits 56 to 58

Exhibit 56. Results of logistic regression using the derivation dataset for only CABG surgeries

Variable Estimate tValue Probability
Intercept -10.72 -2.92 0.0035
Elective surgery -1.88 -2.43 0.0150
BMI 0.12 3.21 0.0013
History of cancer 3.30 2.56 0.0104
Charlson score* -0.63 -1.88 0.0597
Emergency surgery -1.31 -1.45 0.1479
History of MRSA 3.02 3.57 0.0004
No. of procedures -1.31 -1.99 0.0466
No. of surgeons* 1.07 2.14 0.0326
Postop admission 1.57 2.44 0.0149
Postop glucose* 0.01 0.96 0.3370
Postop hemoglobin -0.33 -1.99 0.0471
Preop albumin 0.98 1.72 0.0863
Preop glucose 0.01 2.02 0.0437
Preop stay -0.45 -1.36 0.1745

* Additional Intermountain risk factor.

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Exhibit 57. Results of logistic regression using the validation dataset for only CABG surgeries.

Variable Estimate tValue Probability
Intercept -3.96 -1.18 0.2365
Elective surgery -0.21 -0.35 0.7255
BMI 0.09 2.55 0.0109
History of cancer@      
Charlson score* -0.33 -1.26 0.2071
Emergency surgery 1.08 1.83 0.0672
History of MRSA 0.91 0.94 0.3456
No. of procedures -0.22 -0.46 0.6476
No. of surgeons* 0.50 0.65 0.5161
Postop admission 1.58 2.75 0.0059
Postop glucose* 0.00 -0.44 0.6635
Postop hemoglobin -0.19 -1.35 0.1782
Preop albumin -0.28 -0.49 0.6246
Preop glucose* -0.01 -0.84 0.3995
Preop stay 0.12 1.68 0.0923

@ No patients in this dataset with had the specific risk factor and no probability could be calculated.
* Additional Intermountain risk factor.

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Exhibit 58. Results of logistic regression using the combined dataset for only CABG surgeries

Variable Estimate tValue Probability
Intercept -7.42 -3.28 0.0011
Elective surgery -0.53 -1.18 0.2365
BMI 0.10 4.19 0.0000
History of cancer 1.60 1.71 0.0875
Charlson score* -0.45 -2.48 0.0132
Emergency surgery 0.14 0.31 0.7555
History of MRSA 1.90 3.37 0.0008
No. of procedures -0.65 -1.68 0.0920
No. of surgeons* 0.68 1.73 0.0831
Postop admission 1.50 3.71 0.0002
Postop glucose* 0.00 0.53 0.5975
Postop hemoglobin -0.24 -2.35 0.0186
Preop albumin 0.28 0.72 0.4716
Preop glucose* 0.00 0.44 0.6570
Preop stay 0.10 1.37 0.1712

* Additional Intermountain risk factor.

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Page last reviewed December 2012
Page originally created December 2012
Internet Citation: Exhibits 56 to 58. Content last reviewed December 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/ssi/ssiexh56-58.html