The accuracy of asthma and respiratory disease diagnostic codes in a managed care medical claims database

Asthma database research is being conducted by many managed care organizations (MCOs) without knowing the accuracy of the diagnostic codes. The purpose of this study was to assess the accuracy of asthma and respiratory disease diagnostic codes by comparing the medical claims database to the medical record. Two groups were identified from the medical claims database of a 300,000-member MCO. The asthma group included patients with a medical claim containing an asthma ICD-9-CM code filed between August 1994 and July 1995. The respiratory group included patients with at least one claim containing an ICD-9-CM code for respiratory conditions other than asthma. The ICD-9-CM code from the medical claims database was compared to the diagnosis reported in the medical record. Criteria were used to classify the level of agreement of ICD-9-CM codes with the medical record. A random sample of 300 patients was chosen, for a total of 1,337 claims. Medical records were available for 217 patients, providing 616 claims available for analysis. Seventy percent of the claims contained one of the ICD-9-CM codes being studied, and 25% contained two codes. The diagnostic codes contained in 85.4% of all claims were in moderate to complete agreement with the medical record. Four percent of the claims were not in agreement with the medical record. The level of agreement for 10% of the claims could not be determined. Asthma ICD-9-CM codes found in a managed care medical claims database are reasonably accurate and quite adequate for research purposes and disease management monitoring.