ABSTRACT
A patient-reported outcome (PRO) is any report on the status of a patient’s health condition that comes directly from the patient, without interpretation of the patient’s response by a clinician or anyone else. In this chapter several aspects of PRO scale development and validation are discussed. The first and most important step discussed in this process involves the establishment of content validity through qualitative methods in order to ascertain that the measured concepts cover what patients consider to be the important outcomes of the condition and its therapy. This chapter continues with an exposition of construct validity (to gauge whether the PRO instrument is measuring what it is intended to measure) and its various forms: convergent and divergent validity, known-groups validity and criterion validity, along with special cases of them. Also detailed are two advanced forms of validity assessment, namely, exploratory factor analysis and confirmatory factor analysis. Person-item maps are featured as a way to examine the validity of a PRO measure. The topic of reliability, which is discussed in terms of reproducibility (stability of measurement), is addressed with repeatability reliability and internal consistency reliability.
