2018 changes in nhsn c.difficilesurveillance 887
table 1. Comparison Between the Previous and the Current Clostridium difficile Infection (CDI) Model of Hospital-Onset (HO) LabID-CDI Event Standardized Infection Ratio (SIR)When Using Enzyme Immunoassay (EIA) Versus Nucleic Acid Amplification Test (NAAT)
Previous CDI Model
Lab Method EIAd
NAATe
Lab Method EIAi
NAATj
HO-CDI Events Observeda 88
247 Current CDI Model
HO-CDI Events Observedf 88
247
HO-CDI Events Expectedg 144.9
277.1
HO LabID-CDI Event SIRh 0.61
0.89
(medical school affiliation=graduate*)] × CDI patient days cThe CDI LabID SIR is calculated by dividing the number of observed HO CDI LabID events by the number of expected events. dNo. of predicted LabID events=exp[−7.8983+0.385*0+0.1606*1+0.3338*(0.43)+0.2164*1+0.0935*0+0.187*1+0.0918*1]*213,404,
where NAAT=1 and EIA=0. Assumes that EIA positive samples are all NAAT positive. fNo. of predicted LabID events=exp(β0+β1X1+β2X2+…)*patient days gNo. of predicted (expected) HO CDI LabID events=EXP[−8.9463+0.7339*(CO CDI prevalence rate) −0.1579 (CDI test
type=EIA*)+0.1307 (CDI test type=NAAT*)+0.7465 (ICU beds ≥43*)+0.7145 (ICU beds: 20–42*)+0.6261 (ICU beds: 10–19*)+0.4394 (ICU beds: 5–9*)+1.2420 (oncology hospital*)+0.3740 (general hospital)+0.0003 (total facility bed size*)+0.1119 (reporting from ED or 24
h Obs)+0.0331 (teaching hospital*)] × CDI patient days hThe CDI LabID SIR is calculated by dividing the number of observed HO CDI LabID events by the number of expected events. iNo. of predicted LabID events=exp[−8.9463+0.7339*(0.43)
−0.1579*1+0.1307*0+0.7465*1+0.7145*0+0.6261*0+0.4394*0+1.2420*0+0.3740*1+0.0003*761+0.1119*1+0.0331*1]*213,404,
where EIA=1 jNo. of predicted LabID events=EXP [−8.9463+0.7339*(0.92) −0.1579*0+0.1307*1+0.7465*1+0.7145*0+0.6261*0+0.4394*0+1.2420*0+0.3740*1+0.0003*761+0.1119*1+0.0331*1]*213,404, where NAAT=1 and EIA=0. Assumes that EIA-positive samples are all NAAT positive.
LabID-CDI events, regardless of the “direction” of the test algorithm.
acknowledgments
Financial support: No financial support was provided relevant to this article. Potential conflicts of interest: All authors report no conflicts of interest relevant to this article.
Alexandre R. Marra;1,2 Michael B. Edmond;1,3 Bradley A. Ford;4
Loreen A. Herwaldt;3
Abdullah R. Algwizani;5 Daniel J. Diekema1,3,4
Affiliations: 1. Office of Clinical Quality, Safety and Performance Improvement, University of Iowa Hospitals and Clinics, Iowa City, Iowa; 2. Division of Medical Practice, Hospital Israelita Albert Einstein, Sao Paulo, Brazil; 3. Division of Infectious Diseases, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa; 4. Division
of Medical Microbiology, Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa; 5. Division of Infectious Diseases, Department of Medicine, King Abdulaziz Medical City, Riyadh, Saudi Arabia. Address correspondence to Alexandre Rodrigues Marra, MD, University
of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242 (
alexandre-rodriguesmarra@uiowa.edu). Infect Control Hosp Epidemiol 2018;39:886–888 © 2018 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2018/3907-0023. DOI: 10.1017/ice.2018.86
references
1. Marra AR, Edmond MB, Ford BA, Herwaldt LA, Algwizani AR, Diekema DJ. Failure of risk-adjustment by test method for C. difficile laboratory-identified event reporting. Infect Control Hosp Epidemiol 2017;38:109–111.
2. The NHSN standardized infection ration (SIR)—a guide to the SIR. Centers for Disease Control and Prevention website. https://
www.cdc.gov/nhsn/pdfs/ps-analysis-resources/nhsn-sir-guide.pdf. Updated July 2017. Accessed February 19, 2018.
NOTE. ED, emergency department; 24 h Obs, 24-hour observation location. UIHC total facility bed size, 761. aNo. of predicted LabID events=exp (β0+β1X1+β2X2+…) × patient days bNo. of predicted (expected)HOCDI LabID events=exp[−7.8983+0.385 (CDI test type=NAAT*)+0.0160 (CDI test type=EIA*)+0.3338* (CO CDI prevalence rate)+0.2164 (bed size >245*)+0.0935 (bed size=101–245 beds*)+0.187 (medical school affiliation=major*)+0.0918
where EIA=1 eNo. of predicted LabID events= exp[−7.8983+0.385*1+0.1606*0+0.3338*(0.92)+0.2164*1+0.0935*0+0.187*1+0.0918*1]*213,404,
HO-CDI Events Expectedb 176.3
259.8
HO LabID-CDI Event SIRc 0.50
0.95
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