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Exhibits 8 To 10

Exhibit 8. Distribution of SSI among surgeries in VASQIP data

 CABG HERNIA KNEE HIP  TOTAL 
Total Procedures4525 19692 7467 3867 35551 
Surgical Site Infections#SSI% Total#SSI% Total#SSI% Total#SSI% Total#SSI% Total
sSSI10893.116574.76159.24051.337472.2
dSSI86.93616.32928.23342.310620.5
oSSI00.0209.01312.656.4387.3
Total116 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

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Exhibit 9. Preliminary performance on VASQIP training set

 CABGHERNIAKNEEHIP
Total Cases45251969274673867
Positive SSITP8FN0TP52FN4TP39FN3TP36FN2
Negative SSIFP402TN4115FP1004TN18632FP873TN6552FP295TN3534
ID by Alg410411510561863691265553313536
% Excluded by Alg90.9494.6487.7991.44
Diagnostic Accuracy
Sensitivity100.00%92.86%92.86%94.74%
Specificity91.10%94.89%88.24%92.30%
PPV1.95%4.92%4.28%10.88%
NPV100.00%99.98%99.95%99.94%
AUROC95.60%93.90%90.50%93.50%
Time Saving
NNR w/Alg51.2520.3123.389.19
NNR s/Alg555.56357.14178.57102.04

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.

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

 Total SurgeriessSSIdSSIoSSI
Total3555137410638
 Surgeries Flagged# Caught (Sensitivity)
Rpart Algorithm2709 (7.6%)156 (41.7%)101 (95.3%)34 (89.5%)
Inclusive Algorithm7961 (22.4%)328 (87.7%)104 (98.1%)35 (92.1%)
Simple6939 (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

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Current as of December 2012
Internet Citation: Exhibits 8 To 10. December 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/ssi/ssiexh8-10.html