Interrater reliability of measurements of comorbid illness should be reported

OBJECTIVE: Comorbidity indices are commonly used to stratify patients to control for treatment selection bias. The objectives here were to review the reporting of interrater reliability when studies use comorbidity indices in clinical research publications and to report the interrater reliability of four common indices in a particular research setting. STUDY DESIGN AND SETTING: Four trained abstractors reviewed the same 40 charts of patients …