Bmc Nephrol
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Administrative claims are a rich source of information for epidemiological and health services research; however, the ability to accurately capture specific diseases or complications using claims data has been debated. In this study, the authors examined the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for the identification of hyponatremia in an outpatient managed care population. ⋯ ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.