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Administrative coding data, compared with CDC/NHSN criteria, are poor indicators of health care-associated infections
Kurt B Stevenson1, Yosef Khan, Jeanne Dickman
1Department of Clinical Epidemiology, Ohio State University Medical Center, Columbus, OH 4320, USA. kurt.stevenson@osumc.edu
Insights
Administrative coding alone is an inaccurate method for health care-associated infection (HAI) surveillance. Its use for public reporting and performance comparisons is questionable due to low positive predictive values.
Area of Science:
- Infection Control and Hospital Epidemiology
- Health Services Research
- Medical Informatics
Background:
- Health care-associated infections (HAIs) surveillance is critical for patient safety.
- International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) coding has been proposed for HAI surveillance.
- The accuracy of ICD-9-CM coding for HAI surveillance relative to established criteria is unknown.
Purpose of the Study:
- To evaluate the accuracy of ICD-9-CM coding as a standalone method for HAI surveillance.
- To compare ICD-9-CM code-identified HAIs with those identified by established infection control surveillance methods.
Main Methods:
- Retrospective analysis of patients at an academic medical center in 2005.
- Comparison of HAIs identified by ICD-9-CM codes versus Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN) methods.
- Rereview and adjustment of discordant cases identified solely by coding.
- Estimation of false negatives in cases where both coding and surveillance were negative.
Main Results:
- Positive predictive values (PPVs) for ICD-9-CM coding ranged from 0.14 to 0.51 (aggregate 0.23), even after adjustments.
- Negative predictive values (NPVs) ranged from 0.91 to 1.00 (aggregate 0.96).
- Low PPVs were primarily attributed to the prevalence of surgical site infections.
Conclusions:
- Administrative ICD-9-CM coding alone is an inadequate tool for infection control surveillance.
- The routine use of administrative coding for HAI surveillance, public reporting, interfacility comparisons, and nonpayment for performance should be reconsidered.
- More robust surveillance methods are necessary for accurate HAI monitoring.
Background:
ICD-9-CM coding alone has been proposed as a method of surveillance for health care-associated infections (HAIs). The accuracy of this method, however, relative to accepted infection control criteria is not known.
Methods:
Retrospective analysis of patients at an academic medical center in 2005 who underwent surgical procedures or who were at risk for catheter-associated bloodstream infections or ventilator-associated pneumonia was performed. Patients previously identified with HAIs by Centers for Disease Control and Prevention's National Healthcare Safety Network surveillance methods were compared with those of the same risk group identified by secondary infection ICD-9-CM codes. Discordant cases identified by only coding were all rereviewed and adjusted prior to final analysis. When coding and surveillance were both negative, a sample of patients was used to estimate the proportion of false negatives in this group.
Results:
The positive predictive values (PPVs) ranged from 0.14 to 0.51 with an aggregate of 0.23, even after adjustment for additional cases detected on subsequent medical record review. The negative predictive values (NPVs) ranged from 0.91 to 1.00, with an aggregate of 0.96. The estimates of the true variance of PPVs and NPVs across surgical procedures were small (0.0129, standard error, 0.009; 0.000145, standard error, 0.00019, respectively) and could be mostly explained by variation in prevalence of surgical site infections.
Conclusion:
Administrative coding alone appears to be a poor tool to be used as an infection control surveillance method. Its proposed use for routine HAI surveillance, public reporting of HAIs, interfacility comparisons, and nonpayment for performance should be seriously questioned.
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