Neurologists' use of ICD-9CM codes for dementia

Neurologists' use of ICD-9CM codes in a sample of 181 consecutive, new pati ents evaluated for dementia by 48 of all 49 neurologists from the Rochester , NY, area over a I-year period was examined. The specific code for AD, 331 .0, was used for only 36.5% of patients judged by the neurologist to have A D as the mast likely diagnosis. Other codes used were not inaccurate but wo uld result in lower reimbursement. Variation in coding could affect validit y of dementia research using claims data.