Accuracy of formal tests for diagnosing mild aphasia: An application of evidence‐based medicine

Background: Normal elderly and mildly aphasic individuals may exhibit similar impairments in language comprehension and expression. Accurate differential diagnosis is essential for providing a prognosis, focusing treatment, and justifying reimbursement for services. Aims: We employed the principles of evidence‐based medicine to examine the accuracy of two general language tests (Porch Index of Communicative Ability; Western Aphasia Battery) and two functional communication tests (Communication Activities of Daily Living; American Speech‐Language‐Hearing Association's Functional Assessment of Communication Skills for Adults) for diagnosing mild aphasia, beyond individual clinical expertise. Methods & Procedures: The test performance of 10 mildly aphasic patients was compared with that of 10 non‐brain‐injured (NBI) adults. An operational definition of aphasia was applied as a reference standard for correct diagnosis. Pre‐test and post‐test diagnostic probabilities were compared, using the likelihood ratio a...