Does clinical evidence support ICD-9-CM diagnosis coding of complications?

BACKGROUND. Hospital discharge diagnoses, coded by use of the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) , increasingly determine reimbursement and support quality monitoring. Prio r studies of coding validity have investigated whether coding guidelines we re met, not whether the clinical condition was actually present. OBJECTIVE. TO determine whether clinical evidence in medical records confir ms selected ICD-9-CM discharge diagnoses coded by hospitals. RESEARCH DESIGN AND SUBJECTS. Retrospective record review of 485 randomly s ampled 1994 hospitalizations of elderly Medicare beneficiaries in Californi a and Connecticut. MAIN OUTCOME MEASURE. Proportion of patients with specified ICD-9-CM codes representing potential complications who had clinical evidence confirming t he coded condition. RESULTS. Clinical evidence supported most postoperative acute myocardial in farction diagnoses, but fewer than 60% of other diagnoses had confirmatory clinical evidence by explicit clinical criteria; 30% of medical and 19% of surgical patients lacked objective confirmatory evidence in the medical rec ord. Across 11 surgical and 2 medical complications, objective clinical cri teria or physicians' notes supported the coded diagnosis in >90% of patient s for 2 complications, 80% to 90% of patients for 4 complications, 70% to < 80% of patients for 5 complications, and <70% for 2 complications. For some complications (postoperative pneumonia, aspiration pneumonia, and hemorrha ge or hematoma), a large fraction of patients had only a physician's note r eporting the complication. CONCLUSIONS. Our findings raise questions about whether the clinical condit ions represented by ICD-9-CM codes used by the Complications Screening Prog ram were in fact always present. These findings highlight concerns about th e clinical validity of using ICD-9-CM codes for quality monitoring.