Clinical Guide to the Evidence-Based Assessment Approach to Diagnosis and Treatment

•Evidence-based assessment can work in most clinical settings for common problems•EBA combines base rates, risk factors, and checklists quickly and accurately•Clinicians work with clients to decide when to test more and how to treat•EBA helps define benchmarks for treatment progress and outcome•A case example illustrates EBA methods in practice

Assessment plays an essential role in diagnosis, treatment planning, and progress monitoring, but assessment data are often used in ways that are impressionistic and prone to biases. Evidence-based medicine (EBM) principles, underutilized in psychology, can be used to streamline the assessment process and increase the accuracy of conclusions. Using a case example to illustrate the application of each step, this paper outlines a 12-step approach for applying EBM assessment strategies in clinical practice. The initial steps utilize information about clinical base rates, psychopathology risk factors, rating scale scores, and selected in-depth assessment to conduct an iterative, efficient approach to estimating the probability of a given diagnosis until that probability falls into a range suggesting the diagnosis is unlikely to be present, or likely enough to warrant treatment. Once the practitioner and client agree on the treatment plan, subsequent steps monitor progress and outcomes and use that information to make decisions about termination, and then continued monitoring guards against relapse.