Administrative codes combined with medical records based criteria accurately identified bacterial infections among rheumatoid arthritis patients

UMMS Affiliation

Department of Quantitative Health Sciences

Publication Date


Document Type



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.

DOI of Published Version



J Clin Epidemiol. 2009 Mar;62(3):321-7, 327.e1-7. Epub 2008 Oct 1. Link to article on publisher's site

Journal/Book/Conference Title

Journal of clinical epidemiology

PubMed ID


Related Resources

Link to Article in PubMed