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

Academic Article


  • 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.
  • Published In


  • 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
  • Digital Object Identifier (doi)

    Author List

  • Patkar NM; Curtis JR; Teng GG; Allison JJ; Saag M; Martin C; Saag KG
  • Start Page

  • 321
  • End Page

  • 327.e7
  • Volume

  • 62
  • Issue

  • 3