Accuracy of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) As a Research Tool for Identification of Patients with Uveitis and Scleritis

Abstract

While the use of ICD-9-CM codes has been validated for medical research of common diseases, our results suggest that ICD-9-CM codes may be of limited value for epidemiological investigations of diseases which can be more difficult to diagnose. The ICD-9-CM codes for rarer diseases (PMR, uveitis and scleritis) did not reflect the true clinical problem in a large proportion of our patients. This is particularly true when coding is performed by physicians outside the area of specialty of the diagnosis.