ssiexh8-10.htm

Exhibit 8. Distribution of SSI among surgeries in VASQIP data

	CABG		HERNIA		KNEE		HIP		TOTAL
Total Procedures	4525		19692		7467		3867		35551
Surgical Site Infections	#SSI	% Total	#SSI	% Total	#SSI	% Total	#SSI	% Total	#SSI	% Total
sSSI	108	93.1	165	74.7	61	59.2	40	51.3	374	72.2
dSSI	8	6.9	36	16.3	29	28.2	33	42.3	106	20.5
oSSI	0	0.0	20	9.0	13	12.6	5	6.4	38	7.3
Total	116		221		103		78		518

SSI = surgical site infections, VASQIP = Veterans Affairs-Surgical Quality Improvement Program, CABG = coronary artery bypass grafting, HERNIA = herniorraphy, KNEE = total knee arthroplasty, HIP = total hip arthroplasty, #SSI = number of SSI, % Total = percent of all SSI, sSSI = superficial SSI, dSSI = deep SSI, oSSI = organ space SSI

Return to Document

Exhibit 9. Preliminary performance on VASQIP training set

	CABG		HERNIA		KNEE		HIP
Total Cases	4525		19692		7467		3867
Positive SSI	TP8	FN0	TP52	FN4	TP39	FN3	TP36	FN2
Negative SSI	FP402	TN4115	FP1004	TN18632	FP873	TN6552	FP295	TN3534
ID by Alg	410	4115	1056	18636	912	6555	331	3536
% Excluded by Alg	90.94		94.64		87.79		91.44
Diagnostic Accuracy
Sensitivity	100.00%		92.86%		92.86%		94.74%
Specificity	91.10%		94.89%		88.24%		92.30%
PPV	1.95%		4.92%		4.28%		10.88%
NPV	100.00%		99.98%		99.95%		99.94%
AUROC	95.60%		93.90%		90.50%		93.50%
Time Saving
NNR w/Alg	51.25		20.31		23.38		9.19
NNR s/Alg	555.56		357.14		178.57		102.04

Alg = algorithm, AUROC = area under receiver-operator curve, CABG = coronary artery bypass grafting, HERNIA = herniorraphy, ID = identified, KNEE = total knee arthroplasty, HIP = total hip arthroplasty, NNR= number needed to read, NPV = negative predictive value, PPV = positive predictive value.

Return to Document

Exhibit 10. Performance of different algorithms by SSI type on the training set

	Total Surgeries	sSSI	dSSI	oSSI
Total	35551	374	106	38
	Surgeries Flagged	# Caught (Sensitivity)
Rpart Algorithm	2709 (7.6%)	156 (41.7%)	101 (95.3%)	34 (89.5%)
Inclusive Algorithm	7961 (22.4%)	328 (87.7%)	104 (98.1%)	35 (92.1%)
Simple	6939 (19.5%)	318 (85.0%)	103 (97.2%)	34 (89.5%)

SSI = surgical site infection. sSSI = superficial SSI. dSSI = deep SSI. oSSI = organ-space SSI. Inclusive algorithm looks for any high-normal value. Rpart algorithm refers to the algorithm derived using the Rpart procedure. ( ) = percentage of total

Return to Document

Current as of December 2012

Internet Citation: ssiexh8-10.htm. December 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/ssi/ssiexh8-10.html