State three or more psychometric properties that are commonly reported in studies of outcome measures.
State two important characteristics to consider when appraising the applicability of a study of an outcome measure.
State two types of outcome measure reliability that are studied.
Describe two important design features you consider when appraising the quality of a reliability study.
State two types of outcome measure validity that are studied.
State important design features to consider when appraising the quality of a criterion-related study of outcome measure validity.
This chapter addresses the appraisal of studies of outcome measures. Outcome measures provide information about patients and their progress. Choosing appropriate outcome measures for your patients is critical to understanding their status and progress over time. Ideally, the psychometric properties of an outcome measure used in practice have been developed and tested through a series of research studies. Psychometric properties are the intrinsic properties of an outcome measure and include reliability, validity, and clinical meaningfulness (Fig. 10.1). Understanding the research used to develop and assess outcome measure psychometric properties empowers you to select and use outcome measures effectively in your practice.
The appraisal process for studies of reliability, validity, and clinical meaningfulness of outcome measures.
We begin this chapter by defining common features of outcome measures and describing the different categories of outcome measures that you are likely to encounter in clinical practice, that is, questionnaires and performance-based measures. This chapter does not focus on the appropriate use of outcome measures in a particular research study; rather, we focus on how you can use the appraisal process to determine whether a study of an outcome measure is applicable, valid, and clinically useful. We review the appraisal of studies of reliability, validity, and clinical meaningfulness of outcome studies and provide corresponding checklists of appraisal with key questions in Tables 10.6, 10.8, and 10.9.
Types and Utility of Outcome Measures
What Is an Outcome Measure?
An outcome measure is any characteristic or quality measured to assess a patient's status. Outcome measures are commonly collected at the beginning, middle, and end of a course of physical therapy care. Outcome measures that you are likely to encounter in clinical practice can be divided into two categories: (1) questionnaires and (2) performance-based measures. Questionnaires require that either a therapist interviews a patient or the patient independently completes the questionnaire. Questionnaires are typically scored by applying a pre-set point system to the patient's answers. Performance-based measures require the patient to perform a set of movements or tasks. Scores for performance-based measures can be based on either an objective measurement (e.g., time to complete a task) or a qualitative assessment that is assigned a score (e.g., ...