Measuring clinically important changes with patient-oriented questionnaires.

Background: The measurement of the patient's experience with a condition or an illness is an important and quantifiable outcome and an example of action research. By making these concerns paramount, the goals and processes of health care can be redirected from anatomical and physiologic restoration to patient-oriented outcomes. At the same time, research can illuminate the complex mechanisms responsible.
Methods: Critical, analytic synthesis and review of the research evaluating the ability of self-administered questionnaires to capture clinically meaningful changes.
Results: Responsiveness is differentiated from sensitivity, and statistical methods for evaluating sensitivity of instruments are referenced. Techniques for evaluating whether differences in instrument sensitivity could have occurred by chance are presented, and methods for assessing a clinically meaningful change are discussed.
Conclusion: Responsiveness is the key psychometric property of an instrument if it is to be incorporated into daily practice. Improving responsiveness is a major research priority.