Towards guidelines for evaluation of measures: an introduction with application to spinal cord injury

BACKGROUND: Both clinical practice and research in spinal cord injury (SCI) continue to struggle with issues of the quality and utility of outcome measures employed. Despite widespread deference to dicta on "reliability and validity," systematic means of grading the level of evidence for measures are lacking. OBJECTIVES: This paper explains the methods and principles for use in systematic reviews of measures in SCI. It explains how extant measurement standards and principles can be elaborated for extant labels on various types of reliability and validity to define a more judicious method of grading level of evidence. We aim to initiate a process of discussion that will lead to improved systematic review of the measurement quality as a basis for long-term improvements in outcomes measures and their application. METHODS: This paper is a conceptual review, based on established measurement standards and principles and the incorporation of recent advances in measurement methodology. The scheme of grading of measurement quality is illustrated by examples of measures of health, function, activity/participation, and quality of life after SCI. RESULTS AND CONCLUSIONS: It is possible to grade the quality of outcome measure in terms of level of evidence, provided the nature of the construct being measured is defined as well as its main use. Definite means of grading the level of evidence for measurement will help to identify priorities for measure development and facilitate more appropriate uses of measures.