ssiexh29-31.htm

Exhibit 29. Results of logistic regression using the 60-percent derivation set, including each of the five surgical procedures as a possible risk factor

Variable	Estimate	tValue	Probability
Intercept	-5.66922	-7.18334	0.00000
Admission transfer	0.249358	0.655373	0.51223
History of cancer	0.675356	1.234336	0.21708
Chronic kidney disease	-2.28736	-2.24028	0.02507
General anesthesia	0.419425	1.499021	0.13387
Male	0.58722	2.677562	0.00742
History of MRSA	1.47331	4.87133	0.00000
Number of procedures	0.381148	3.171798	0.00151
Postop admission	2.104624	9.115523	0.00000
Postop hematocrit	-0.04406	-2.01137	0.04496
Preop stay	0.042437	1.623837	0.10441
CABG surgery	0.24496	0.746911	0.45512
Herniorrhaphy	0.186762	0.564969	0.57209
Wound class	0.003031	0.014814	0.98818

CABG = coronary artery bypass grafting; MRSA = methicillin-resistant Staphylococcus aureus; Postop = postoperative; Preop = preoperative.

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Exhibit 30. Results of logistic regression using the 40-percent validation set, including each of the five surgical procedures as a possible risk factor

Variable	Estimate	tValue	Probability
Intercept	-5.9448	-7.7606	0.00000
Admission transfer	-0.46026	-0.92513	0.35490
History of cancer	-0.78305	-0.76388	0.44494
Chronic kidney disease	-0.49964	-0.91168	0.36193
General anesthesia	0.046769	0.171229	0.86404
Male	-0.08612	-0.3914	0.69550
History of MRSA	1.149853	3.048832	0.00230
Number of procedures	0.264643	1.861373	0.06269
Postop admission	2.115295	9.348542	0.00000
Postop hematocrit	-0.01706	-0.79509	0.42677
Preop stay	0.035891	1.814288	0.06963
CABG surgery	0.725095	2.077166	0.03779
Herniorrhaphy	0.553825	1.787663	0.07383
Wound class	0.326074	1.904355	0.05686

CABG = coronary artery bypass grafting; MRSA = methicillin-resistant Staphylococcus aureus; Postop = postoperative; Preop = preoperative.

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Exhibit 31. Results of logistic regression using the combined derivation and validation sets, including each of the five surgical procedures as a possible risk factor

Variable	Estimate	tValue	Probability
Intercept	-5.75478	-10.6587	0.00000
Admission transfer	-0.07527	-0.25258	-0.25258
History of cancer	0.186484	0.396676	0.69161
Chronic kidney disease	-1.19328	-2.52852	0.01145
General anesthesia	0.248213	1.277382	0.20147
Male	0.254338	1.658706	0.09718
History of MRSA	1.347607	5.798036	0.00000
Number of procedures	0.322013	3.494699	0.00047
Postop admission	2.111179	13.10889	0.00000
Postop hematocrit	-0.03231	-2.16588	0.03045
Preop stay	0.035145	2.315832	0.02057
CABG surgery	0.477163	2.015653	0.04384
Herniorrhaphy	0.376815	1.673907	0.09415
Wound class	0.16983	1.300158	0.19355

CABG = coronary artery bypass grafting; MRSA = methicillin-resistant Staphylococcus aureus; Postop = postoperative; Preop = preoperative.

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Current as of December 2012

Internet Citation: ssiexh29-31.htm. December 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/ssi/ssiexh29-31.html