Health measurement development and interpretation

Abstract

Outcome measures help clinicians assess the risks and benefits of treatment in relation to a multi-faceted definition of health. While surrogate outcomes, including performance-based tests, provide important measures of health, patient-reported outcome measures (PROMs) assess both specific and general factors of how a patient's health affects their ability to participate in desired family and societal roles and activities. Clinicians electing to use measurement tools to evaluate patient progress, to inform decision-making, or for research purposes must understand the measurement properties of the instrument to select the most appropriate measure. An instrument with sufficient measurement properties will have demonstrated reliability, validity, and evidence of its ability to detect important change in the applicable population. For ease of communication, results should be presented using easily interpretable statistics that convey the clinical meaning of the results, including providing readers with a threshold with which to judge clinical importance and confidence intervals (CI) around within-group changes (if measuring pre- to post-intervention), around between-group differences (if comparing different interventions), and using summary measures such as number needed to treat (NNT). In this chapter, we will outline the purpose of different outcome measures, measurement properties, and methods of presenting the results to improve the broad communication of results.