1. Post-operative Infection Treatment Score for the Spine (PITSS): Validation of a Predictive Model to Define Need for Single versus Multiple Irrigation and Debridement for Spinal Surgical Site Infection Christian P. DiPaola, MD 1; Davor D. Saravanja 2, MD; Luca Boriani,MD 3; Michael Boyd, MD 4; Brian K. Kwon, MD, PhD 4; Scott Paquette 4, MD; Marcel F. S. Dvorak, MD 4; Charles G. Fisher, MD, MHSc 4, John Street, MD, PhD 4 1University of Massachusetts Medical Center, Worcester, MA 2 Sydney Children’s Hospital, Sydney, Australia 3 Ospedale Maggiore , Bologna Italy 4University of British Columbia, Vancouver, BC

2. Background Rx=I&D

3. Closed Suction Irrigation for the Treatment of Postoperative Wound Infections Following Posterior Spinal Fusion and Instrumentation Michael T. Rohmiller, MD,* Behrooz A. Akbarnia, MD,†‡ Kian Raiszadeh, MD,§ Kamshad Raiszadeh, MD,¶ and Sarah Canale, BS‡

4. SSI: Complex SSI Management V.A.C.

6. SSI: Complex SSI Management

16. Purpose Study #1 Study #2 137.40 8 IPSI X17 135.85 140 CSF X16 134.45 387 Gender X15 132.45 443 Neurologic Deficit X14 130.55 445 Levels X13 128.72 450 Previous Surgery X12 126.79 455 Duration of ICU stay X11 124.89 463 Primary Spine Diagnosis X10 120.28 464 Index procedure duration X9 118.92 486 Hospital Duration Preop X8 117.77 561 Patient Age X7 117.30 M5+X6 M6 710 Bone graft X6 119.32 M4+X5 M5 721 Instrumentation X5 124.38 M3+X4 M4 725 Distant site Infection X4 125.97 M2+X3 M3 739 Medical Comorbidities X3 125.72 M1+X2 M2 768 Spine Location X2 122.81 X1 M1 853 Wound Culture Microbiology X1 AIC Predictors in the model Model Frequency Description Ranked Predictor Internal Validation of Predictor Selection using 1000 re-samples (predictability measure AUC=0.84 for model M6)

17. 130.55 445 Levels X13 128.72 450 Previous Surgery X12 126.79 455 Duration of ICU stay X11 124.89 463 Primary Spine Diagnosis X10 120.28 464 Index procedure duration X9 118.92 486 Hospital Duration Preop X8 117.77 561 Patient Age X7 117.30 M5+X6 M6 710 Bone graft X6 119.32 M4+X5 M5 721 Instrumentation X5 124.38 M3+X4 M4 725 Distant site Infection X4 125.97 M2+X3 M3 739 Medical Comorbidities X3 125.72 M1+X2 M2 768 Spine Location X2 122.81 X1 M1 853 Wound Culture Microbiology X1 AIC Predictors in the model Model Frequency Description Ranked Predictor Internal Validation of Predictor Selection using 1000 re-samples (predictability measure AUC=0.84 for model M6)

20. External validation The predictability (measured by AUC – area under curve) of the final prediction model was checked with the validation dataset (2006-2008) and its re-samples. The curve referred to here is the ROC ( Receiver Operating Characteristic ). The closer AUC is to 1.0 the better the prediction power. AUC=0.70 95% CI = (0.51, 0.89)

22. 0 other graft -0.4647 autograft 0.0630 -1.7848 none Bone graft 0 yes 0.0450 -1.9550 no Instrumentation 0 Bacteremia+dist 0.0850 Bacteremia+alone -0.3082 UTI/pneumonia 0.0876 -1.7743 none Distant Site Infection 0 Others (ie. GI, renal etc.) 0.4218 cardiovascular/pulmonary 2.0241 diabetes 0.1736 0.2039 none Comorbidities 0 Lumbar/sacral (L1-S2) -1.0658 Thoracic or thoraco-lumbar (T1-L1) 0.1613 -1.5069 Cervical (C0-7) IP Location 0 Polymicrobial with MRSA or MRSA alone -1.9639 Gram negative or polymicrobial wo MRSA 0.0389 -1.4416 Gram positive Microbiology Pvalue Coeffecient Predictor subgroups Predictors

23. Post-operative Infection Treatment Score for the Spine Low risk: 7-14 Indeterminate: 15-20 High risk 21-33 6 Other (allograft, BMP, synthetic) 3 Autograft 1 None Bone Graft 6 Yes 2 No Instrumentation Surgical Factors 6 Bacteremia + PNA/UTI 5 Bacteremia alone 3 UTI/pneumonia 1 none Distant site infection 6 Polymicrobial with MRSA or MRSA alone 4 Gram negative or polymicrobial wo MRSA 2 Gram positive Microbiology Infection Factors 4 diabetes 1 cardiovascular/pulmonary 0 None/other Comorbidities Patient Factors 4 Lumbar/sacral 2 Thoracolumbar 1 Cervical Spine Location Spine Factors

24. Applying the Data Multiple I&D Single I&D 14 20 NPV=.71 PPV=.98 Low risk: 7-14 Indeterminate: 15-20 High risk 21-33 Low Risk High Risk Unsure

25. PITSS Example Patient 28 Multiple I&D Single I&D 14 20 Low risk: 7-14 Indeterminate: 15-20 High risk 21-33 6 Other (allograft, BMP, synthetic) 3 Autograft 1 None Bone Graft 6 Yes 2 No Instrumentation Surgical Factors 6 Bacteremia + PNA/UTI 5 Bacteremia alone 3 UTI/pneumonia 1 None Distant site infection 6 Polymicrobial with MRSA or MRSA alone 4 Gram negative or polymicrobial w/o MRSA 2 Gram positive Microbiology Infection Factors 4 Diabetes 1 Cardiovascular/pulmonary 0 None/other Comorbidities Patient Factors 4 Lumbar/sacral 2 Thoracolumbar 1 Cervical Spine Location Spine Factors

27. Thank You