Use of International Classification of Diseases, Ninth Revision, Clinical Modification codes and medication use data to identify nosocomial Clostridium difficile infection.
OBJECTIVE
The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code for Clostridium difficile infection (CDI) is used for surveillance of CDI. However, the ICD-9-CM code alone cannot separate nosocomial cases from cases acquired outside the institution. The purpose of this study was to determine whether combining the ICD-9-CM code with medication treatment data for CDI in hospitalized patients could enable us to distinguish between patients with nosocomial CDI and patients who were admitted with CDI. The primary objective was to compare the sensitivity, specificity, and predictive value of using the combination of ICD-9-CM code for CDI and CDI treatment records to identify cases of nosocomial CDI with the sensitivity, specificity, and predictive value of using the ICD-9-CM code alone.


METHODS
Validation sample cross-sectional study.


METHODS
Academic health center.


METHODS
Administrative claims data from July 1, 2004, to June 30, 2005, were queried to identify adults discharged with an ICD-9-CM code for CDI and to find documentation of CDI therapy with oral vancomycin or metronidazole. Laboratory and medical records were queried to identify symptomatic CDI toxin-positive adult patients with nosocomial CDI and were compared with records of patients whose cases were predicted to be nosocomial by means of ICD-9-CM code and CDI therapy data.


RESULTS
Of 23,920 adult patients discharged from the hospital, 62 had nosocomial CDI according to symptoms and toxin assay. The sensitivity of the ICD-9-CM code alone for identifying nosocomial CDI was 96.8%, the specificity was 99.6%, the positive predictive value was 40.8%, and the negative predictive value was 100%. When CDI drug therapy was included with the ICD-9-CM code, the sensitivity ranged from 58.1% to 85.5%, specificity was virtually unchanged, and the range in positive predictive value was 37.9%-80.0%.


CONCLUSIONS
Combining the ICD-9-CM code for CDI with drug therapy information increased the positive predictive value for nosocomial CDI but decreased the sensitivity.
Department of Pharmacy, College of Pharmacy, University of Illinois at Chicago, Chicago, USA.
Mia
M
Schmiedeskamp
Spencer
S
Harpe
Ronald
R
Polk
Michael
M
Oinonen
Amy
A
Pakyz
D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016360:Clostridioides difficile / Q000187:drug effects / Q000302:isolation & purification; D003015:Clostridium Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D003428:Cross Infection / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D038801:International Classification of Diseases / Q000706:statistics & numerical data; D008297:Male; D016347:Medical Records Systems, Computerized / Q000706:statistics & numerical data; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014481:United States; D014483:United States Dept. of Health and Human Services; D014640:Vancomycin / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D008795:Metronidazole; D014640:Vancomycin