Clinical Outcome Assessment

Original Editor - Adu Omotoyosi Johnson

Top Contributors - Adu Omotoyosi Johnson and Kim Jackson  


A Clinical Outcome Assessment (COA) is any assessment that may be influenced by choices of human, judgement or motivation. COAs must be well-defined and possess adequate measurement properties in order to demonstrate (directly or indirectly) the benefits of a treatment COAs depend on the implementation, interpretation and reporting from a patient, clinician, or an observer.[1]

Types of Clinical Outcome Assessments

  1. Patient-Reported Outcomes (PRO)
  2. Clinician-Reported Outcomes (ClinRo)
  3. Observer-Reported Outcomes (ObsRo)
  4. Performance-Outcome (PerfO)
  • Patient-Reported Outcomes (PRO): This is an outcome where the patient is the rater. PRO assessments rely on a patient’s direct responses to questions. These responses may be recorded by the patient in a variety of ways such as on paper, via computerized questionnaire forms, or via interviews where the patient’s observations or reports are recorded exactly as spoken, without any interpretation (judgment) on the part of the interviewer. Because a patient’s direct report can capture a wide range of feelings and functions, as well as provide a direct measurement of how a patient feels, e.g., pain or low mood, there has been increasing interest in developing PRO COAs. FDA guidance on the topic [2] has highlighted the regulatory agency’s interest in these instruments[1]
  • Clinician-Reported Outcomes (ClinRo): This COA reflects the evaluation of a patient's condition by a healthcare professional, it is based on the report that comes from a trained health care professional after observation of a patient's condition. a good example of this is the pain rating scale
  • Observer-Reported Outcomes (ObsRo): This is a measurement based on an observation by someone other than the patient or a health professional. This is usually done by patient's non-clinical care giver, family or anyone living around such patient and observes the patient in daily life. A good example is the assessment of a patient's cognition.
  • Performance Outcome (PerfO): are a type of COA where the patient is assessed, but no rater judgment impacts the measurement. It is based on the patient’s performance of a defined task that is quantified in a specified way that does not rely on judgment to determine the rating. PerfOs include instruments such as the distance walked in 6 minutes and the number of pictorial symbols correctly matched to a key within a fixed amount of time. Although a clinician or observer is administering and monitoring performance of the PerfO assessment task, this individual does not apply judgment to quantifying the performance. These assessments are still categorized as COAs because a patient’s motivation or volition is involved task performance.[1]

The Context of Use of the COA

The context of use typically includes the following elements;

  • Disease, injury, impairment or condition being treated
  • Patient population demographics (age, disease severity, language, culture, education)
  • Clinical treatment objectives and plan of treatment



  1. 1.0 1.1 1.2 Walton MK, Powers III JH, Hobart J, Patrick D, Marquis P, Vamvakas S, Isaac M, Molsen E, Cano S, Burke LB. Clinical outcome assessments: conceptual foundation—Report of the ISPOR clinical outcomes assessment–emerging good practices for outcomes research task force. Value in Health. 2015 Sep 1;18(6):741-52.
  2. US Food and Drug Administration. Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims. [Accessed July 20, 2014];2009 Available from :