Infection Control & Hospital Epidemiology


1485


Fig. 1. The impact of the NHSN methodology changes on HO-CDI LabID events, predicted HO-CDI LabID events, and NAAT positive ( + )/EIA positive ( + ) events. Rates were calculated based on 10,000 patient days. Note. NHSN, National Healthcare Safety Network; HO-CDI LabID, healthcare facility onset Clostridium difficile laboratory identified event as per NHSN definition; NAAT, nucleic acid amplification test; EIA, toxin enzyme immunoassay; SIR, standardized infection ratio. NAAT + /EIA + events were determined using the monthly counts of HO-CDI LabID events and removing all the events that were NAAT + /EIA − . January 2017 shows a zero for NAAT + /EIA + events as that month reflex EIA had not yet been instituted.


Table 1. Effect of the NHSN Methodology Changes on HO-CDI LabID Events and Standardized Index Ratios Hospital Aa


2017 2018 2017


Hospital Bb 2018


Hospital Cc 2017 2018 Q1 Q2 Q3 Q4 Q1 Q2 Q1 Q2 Q3 Q4 Q1 Q2 Q1 Q2 Q3 Q4 Q1 Q2


HO-CDI LabID events as per NHSN 50 41 54 46 12 16 3 5 2 4 1 1 1 0 1 3 0 1 NAAT + /EIA + NAAT + /EIA −


8d 42d


Predicted HO-CDI LabID event SIRs as reported by NHSN


15 16 17 12 16 2d 26 38 29 36e


52e 1d 21 1


3 131 1 5e


4e


0d 002 01 1d 011 1e


1e


34.7 39.5 36.6 37.8 24.3 23.6 4.8 5.4 4.4 5.3 5.1 4.1 2.0 1.9 1.8 2.0 1.7 1.3 1.4 1.0 1.5 1.2 0.5 0.7 0.6 0.9 0.5 0.8 0.2 0.2 0.5 0 0.6 1.5 0 0.7


Note. NHSN, National Healthcare Safety Network; HO-CDI LabID, healthcare-facility–onset Clostridium difficile laboratory identified event per the NHSN definition; NAAT, nucleic acid


amplification test; EIA, toxin enzyme immunoassay; SIR, standardized infection ratio. aHospital A: 565-bed teaching affiliated hospital with 110 beds assigned to hematology-oncology and solid organ transplant patients. bHospital B: 206-bed community hospital with a new teaching affiliation denomination as of Q1 2018. cHospital C is a 70-bed rural hospital nonteaching affiliated. During 2017, 57 of 194 HO-CDI LabID events were located in the hematology oncology units. All hospitals are located in the


Greater Milwaukee area. dRepresents 2 months of EIA testing. eThese events were not included in the HO-CDI LabID events for that quarter due to the change in NHSN methodology.


manufacturer’s product insert. Hospital A used Xpert C. difficile (Cepheid, Sunnyvale, CA); hospital B used Meridian Illumigene C.diff (Meridian Bioscience, Cincinnati, OH); and hospital C used Nanosphere Verigene C.diff (Luminex, Austin, TX). In February 2017, all stool specimens testing C. difficile positive by any of the NAAT tests were automatically reflexed for TcdA and TcdB EIA testing (C.diff Quik Chek Complete, Alere, Lowell, MA).


Statistics


Counts of events were analyzed using Poisson regression while offsetting for the natural-log of patient days. Due to the low number of events in hospitals B and C, these 2 hospitals counts were combined for all analyses. Changes in SIRs, which were calculated as observed events divided by predicted events, were analyzed using a binomial distribution. All analyses were


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