CAN COMORBIDITY BE MEASURED BY QUESTIONNAIRE RATHER THAN MEDICAL RECORD REVIEW

Comorbidity generally is measured by medical record abstraction, which is expensive and often impractical. The aim of this study was to asse ss the reproducibility and validity of a comorbidity questionnaire. Th e authors developed a brief comorbidity questionnaire that included it ems corresponding to each element of the medical record-based Charlson index. The questionnaire was administered to 170 inpatients. Charlson scores were abstracted from these patients' medical records. We asses sed test-retest reliability of the questionnaire and the Charlson inde x, the correlation between the questionnaire and the Charlson index, a nd correlations between each comorbidity measure and indicators of hea lth resource utilization including medication use, hospitalizations in the past year, and hospital charges. Test-retest reliability, assesse d with the intraclass correlation coefficient, was 0.91 for the questi onnaire and 0.92 for the chart-based Charlson index. The Spearman corr elation between these two measures was 0.63. The correlation between c omorbidity measures was weaker in less educated patients. Correlations with indicators of resource utilization were similar for the two como rbidity instruments. The authors found that a questionnaire version of the Charlson index is reproducible, valid, and offers practical advan tages over medical record-based assessments.