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International Classification of Diseases, 9th Revision, Clinical Modification codes in discharge abstracts are poor
J M Geraci1, C M Ashton, D H Kuykendall
1Houston Center for Quality of Care and Utilization Studies, Houston Veterans Affairs Medical Center, Department of Medicine, Baylor College of Medicine, TX 77030, USA.
Insights
International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes in discharge abstracts poorly identify in-hospital complications. Chart review remains the gold standard for accurately detecting patient complications.
Area of Science:
- Medical Informatics
- Healthcare Quality Improvement
- Patient Safety
Background:
- Accurate identification of in-hospital complications is crucial for patient safety and quality assessment.
- Discharge abstracts containing International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes are widely used for administrative and research purposes.
- The reliability of ICD-9-CM codes for identifying complications has not been fully established.
Purpose of the Study:
- To evaluate the accuracy of ICD-9-CM codes in discharge abstracts for identifying medical inpatients with in-hospital complications.
- To compare the performance of inclusive and exclusive ICD-9-CM code sets in detecting complications.
- To establish the utility of ICD-9-CM codes as a proxy for chart review in complication identification.
Main Methods:
- A chart review was conducted to identify in-hospital complications, serving as the gold standard.
- Two sets of ICD-9-CM codes were extracted from discharge abstracts: an inclusive set and an exclusive set.
- Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance of the code sets.
Main Results:
- Both inclusive (ROC area 0.61) and exclusive (ROC area 0.55) ICD-9-CM code sets demonstrated poor performance in identifying complications.
- Sensitivities for complication detection were low (0.34 for inclusive, 0.14 for exclusive sets).
- Positive predictive values were also suboptimal (0.32 and 0.37, respectively), with generally poor sensitivity for individual complication codes.
Conclusions:
- ICD-9-CM codes in discharge abstracts are not reliable indicators of in-hospital complication occurrence.
- Relying solely on ICD-9-CM codes for complication surveillance may lead to underestimation of patient safety events.
- Further research into improved methods for automated complication detection is warranted.
Objectives:
The authors tested the ability of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes in discharge abstracts to identify medical inpatients who experienced an in-hospital complication, using complications identified through chart review as the gold standard.
Methods:
Two sets of ICD-9-CM codes were used: an inclusive set including many medical diagnoses that may also be coexistent complicating conditions on admission rather than complications and an exclusive set consisting primarily of ICD-9-CM-specified complication and adverse drug event codes.
Results:
Neither set performed well as a diagnostic test for complication occurrence according to receiver operating characteristic analysis (ROC areas were 0.61 for the inclusive set and 0.55 for the exclusive set). Sensitivities of the ICD-9-CM codes for complications were 0.34 for the inclusive set and 0.14 for the exclusive set. Corresponding positive predictive values were 0.32 and 0.37, respectively. Sensitivities of code definitions for individual complications were generally poor, less than 0.5 in most cases.
Conclusions:
The authors conclude that ICD-9-CM codes in discharge abstracts are poor measures of complication occurrence.