Published Sep 2015
Citation
Walton MK, Powers JH III, Hobart J, et al. Clinical outcome assessments: a conceptual foundation – report of the ISPOR Clinical Outcomes Assessment Emerging Good Practices Task Force. Value Health. 2015;18(6):741-752.
Abstract
An outcome assessment, the patient assessment used in an endpoint, is
the measuring instrument that provides a rating or score (categorical or
continuous) that is intended to represent some aspect of the patient’s
health status. Outcome assessments are used to define efficacy endpoints
when developing a therapy for a disease or condition. Most
efficacy endpoints are based on specified clinical assessments of
patients. When clinical assessments are used as clinical trial outcomes,
they are called clinical outcome assessments (COAs).
COAs include any
assessment that may be influenced by human choices, judgment, or
motivation. COAs must be well-defined and possess adequate measurement
properties to demonstrate (directly or indirectly) the benefits of a
treatment. In contrast, a biomarker assessment is one that is subject to
little, if any, patient motivational or rater judgmental influence.
This is
the first of two reports by the ISPOR Clinical Outcomes Assessment –
Emerging Good Practices for Outcomes Research Task Force. This report
provides foundational definitions important for an understanding of
COA measurement principles. The foundation provided in this report
includes what it means to demonstrate a beneficial effect, how assessments
of patients relate to the objective of showing a treatment’s
benefit, and how these assessments are used in clinical trial endpoints.
In addition, this report describes intrinsic attributes of patient assessments
and clinical trial factors that can affect the properties of the
measurements. These factors should be considered when developing or
refining assessments. These considerations will aid investigators designing
trials in their choice of using an existing assessment or developing a
new outcome assessment.
Although the focus of this report is on the
development of a new COA to define endpoints in a clinical trial, these
principles may be applied more generally. A critical element in appraising
or developing a COA is to describe the treatment’s intended benefit
as an effect on a clearly identified aspect of how a patient feels or
functions. This aspect must have importance to the patient and be part
of the patient’s typical life. This meaningful health aspect can be
measured directly or measured indirectly when it is impractical to
evaluate it directly or when it is difficult to measure. For indirect
measurement, a concept of interest (COI) can be identified. The COI
must be related to how a patient feels or functions. Procedures are then
developed to measure the COI. The relationship of these measurements
with how a patient feels or functions in the intended setting and
manner of use of the COA (the context of use) could then be defined.
A COA has identifiable attributes or characteristics that affect the
measurement properties of the COA when used in endpoints. One of
these features is whether judgment can influence the measurement,
and if so, whose judgment. This attribute defines four categories of
COAs: patient reported outcomes, clinician reported outcomes, observer
reported outcomes, and performance outcomes. A full description as
well as explanation of other important COA features is included in this
report. The information in this report should aid in the development,
refinement, and standardization of COAs, and, ultimately, improve their
measurement properties.
Keywords: clinical outcome assessment, concept of interest, context of
use, treatment benefit.
Copyright © 2015, International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc.
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