Administrative codes combined with medical records based criteria accurately identified bacterial infections among rheumatoid arthritis patients
Department of Quantitative Health Sciences
Medical Subject Headings
Aged; Arthritis, Rheumatoid; Bacterial Infections; Cross-Sectional Studies; Female; Forms and Records Control; Humans; International Classification of Diseases; Male; Medical Records; Middle Aged; Sensitivity and Specificity
Bioinformatics | Biostatistics | Epidemiology | Health Services Research
OBJECTIVE: To evaluate diagnostic properties of International Classification of Diseases, Version 9 (ICD-9) diagnosis codes and infection criteria to identify bacterial infections among rheumatoid arthritis (RA) patients.
STUDY DESIGN AND SETTING: We performed a cross-sectional study of RA patients with and without ICD-9 codes for bacterial infections. Sixteen bacterial infection criteria were developed. Diagnostic properties of comprehensive and restrictive sets of ICD-9 codes and the infection criteria were tested against an adjudicated review of medical records.
RESULTS: Records on 162 RA patients with and 50 without purported bacterial infections were reviewed. Positive and negative predictive values of ICD-9 codes ranged from 54%-85% and 84%-100%, respectively. Positive predictive values of the medical records based criteria were 84% and 89% for "definite" and "definite or empirically treated" infections, respectively. Positive predictive value of infection criteria increased by 50% as disease prevalence increased using ICD-9 codes to enhance infection likelihood.
CONCLUSION: ICD-9 codes alone may misclassify bacterial infections in hospitalized RA patients. Misclassification varies with the specificity of the codes used and strength of evidence required to confirm infections. Combining ICD-9 codes with infection criteria identified infections with greatest accuracy. Novel infection criteria may limit the requirement to review medical records.
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Citation: J Clin Epidemiol. 2009 Mar;62(3):321-7, 327.e1-7. Epub 2008 Oct 1. Link to article on publisher's site