Primary Diagnoses Associated with Increased Risk of Hospital Onset Clostridium difficile Infection Open Access

Edison, Laura (2012)

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Background: Clostridium difficile has emerged as a significant cause of healthcare-
associated infections and the most common cause of healthcare associated diarrhea;
increasing in incidence and severity over the last decade. The changing epidemiology
and high cost of the disease has led to efforts to better understand the organism and
how to stratify patients according to their risk of developing Clostridium difficile
infection (CDI) in order to effectively direct infection control efforts and fairly report
hospital infection rates. Little is known about risk stratification using administrative
data sources, and primary diagnosis as a risk factor for infection has rarely been
examined. This thesis examines hospital inpatient primary diagnoses as risk factors for
Hospital Onset CDI (HO-CDI) using administrative data.
Methods: We conducted a retrospective cohort study using hospital discharge data
from the 2009 Nationwide Inpatient Sample, Healthcare Cost and Utilization Project.
HO-CDI was the dependent variable and defined as a non-primary diagnosis of CDI with
a length of stay (LOS) greater than two days. The primary independent variable was the
clinical category (CCS) of the primary diagnosis. LOS, number of chronic conditions, age
category and transfer in from a healthcare facility were examined as possible
confounders or effect modifiers.
Results: Of the 285 CCS examined using multivariate analysis, 23 yielded a significant
risk difference greater than 10/1,000 discharges. All independent variables had a
significant effect on the relationship of CCS to HO-CDI. The CCS that had the strongest
association with HO-CDI are septicemia, HIV, cystic fibrosis and mycoses.
Conclusions: All of the CCS signifcantly associated with HO-CDI are surrogates for
known risk factors, antimicrobial use and healthcare exposure. Administrative data can
be used to determine which CCS are significantly associated with HO-CDI and can be
used to assess a patient's risk for HO-CDI. This risk stratification will improve the ability
of hospital and public health decison makers to allocate resources in preventing HO-CDI,
and can help refine a national CDI reporting system to achieve risk-adjusted
benchmarking of facility infection rates.

Table of Contents

Table of Contents

Introduction. 1

C. difficile Overview. 2

Virulence and Pathogenesis . 2

Clinical Disease. 3

Diagnosis. 4

Treatment. 5

Prevention and Control . 6

C. difficile Epidemiology and Attributable Cost. 7

Risk Factors . 8

C. difficile Surveillance and Mandatory Reporting. 12

Methods. 15

Results. 20

Discussion. 27

Strengths & Limitations. 32

Conclusions and Recommendations. 35

References. 38

Appendix A: Additional Methods. 41

Appendix B: Tables. 43

Appendix C: Emory IRB Exemption Letter. 56

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