Last Update: February 2017
Definition of terms followed by an * are based on the FDA COA glossary of terms or on the glossary included in the FDA Guidance for Industry on Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims, Dec. 2009
Qualitative research technique used to test an instrument in the targeted population, and particularly their comprehension and relevance of instructions, questions, response choices and recall period. It involves incorporating follow-up questions in a field test interview to gain a better understanding of how respondents interpret instructions, questions, response choices and recall period. In this method, respondents are often asked to think aloud and describe their thought processes as they answer the instrument items.
The thing measured by an assessment (e.g. pain intensity).
Qualitative research technique used to explore a theme (e.g. what are the symptoms of a disease and how they impact patients in their daily life). It is recommended that this exploratory interview is conducted by interviewers trained in qualitative interviewing and who are native speakers of the language of the subject interviewed. This kind of interview is semi-structured; the interviewer have a set of topics determined in advance in an interview guide, with open-ended questions to collect spontaneously reported information and probes if the subject does not cover some topics.
Explicit description or diagram of the relationships between the questionnaire or items in a PRO instrument and the concepts measured. The conceptual framework of a PRO instrument evolves over the course of instrument development as empiric evidence is gathered to support item grouping and scores.
Diagram of causal linkages among a set of concepts believed to be related to a particular public health problem. A proximal-to-distal conceptual model is a schematic representation of how concepts may be related to (a) a disease state, (b) a drug under development and (c) each other. It can help establish which of these concepts should be prioritized for measurement in a given trial.
Evidence from qualitative research demonstrating that the instrument measures the concept of interest, including evidence that the items and domains of an instrument are appropriate and comprehensive relative to its intended measurement concept, population, and use. Testing other psychometric properties will not replace or rectify problems with content validity.
Composed of several items and represented by a specific score. An instrument generally comprises multiple domains and measures a larger concept. For example, the VAPI questionnaire assesses subjects' perception and acceptance of influenza vaccination and its subsequent injection site reactions, and it is composed of four domains measuring bother from injection site reactions, arm movement, sleep and acceptability.
Based on an observation by someone other than the patient or an health care professional, this may be a parent, spouse, or other non-clinical caregiver who is in a position to regularly observe and report on a specific aspect of the patient’s health. It does not include medical judgment or interpretation. The use of observer reports is encouraged for patients who cannot respond for themselves (e.g., infants or cognitively impaired). It only includes events or behaviors that can be observed. For example, observers cannot validly report an infant’s pain intensity (a symptom) but can report infant behavior thought to be caused by pain (e.g., crying or wincing). Examples of ObsROs include a parent report of a child’s vomiting episodes or a teacher report of child’s functioning in the classroom.
Based on a report that comes directly from the patient about the status of his/her health condition without amendment or interpretation of the patient’s report by a clinician or anyone else. A PRO can be self-reported or interviewer-administered provided that the interviewer records only the patient’s response. Symptoms or other unobservable concepts known only to the patient (e.g., pain severity or nausea) can only be measured by PRO instruments. PROs can also assess the patient perspective on functioning or activities also observable by others. A lot of different concepts can be measured via PROs; symptoms, HRQL, satisfaction with treatment, well-being, functional status, treatment adherence, global impression of change, etc.
All attributes relevant to the application of a COA instrument, including the content validity, construct validity, reliability, clinical validity and ability to detect change. These attributes are specific to the measurement application and cannot be assumed to be relevant to all measurement situations, purposes, populations, or settings in which the instrument is used.
Period of time responders are asked in responding to an item. Recall can be momentary (real time) or retrospective of varying lengths (24 hours, the past week …). It is generally recommended to be as short as possible to avoid memory bias, given that the concept measured could occur within this time frame.