Review © Future Drugs Ltd. All rights reserved. ISSN 1473-7175 581 CONTENTS Conducting epidemiological research: requirements of a measure of pain severity Existing measures of pain severity: is there an appropriate measure of chronic pain severity for use in epidemiological studies? Measuring chronic pain severity in postal epidemiological studies: using the CPG Questionnaire Expert opinion Five-year view Key issues References Affiliations www.future-drugs.com M easuring the severity of chronic pain: a research perspective Alison M Elliott † , Blair H Smith and W Alastair Chambers The authors of this review are members of the Aberdeen Pain Group, a group of multidisciplinary researchers who have been researching chronic pain for over 10 years. This review draws upon their experience to consider the measurement of chronic pain severity from a research perspective. The first half summarizes the requirements of a measure of pain severity for epidemiological research, describes a number of existing measures of pain severity and discusses the appropriateness of these instruments for measuring chronic pain as part of a postal epidemiological survey. The second half focuses on the use of the Chronic Pain Grade questionnaire by the Aberdeen Pain Group. The reliability and validity of this instrument as part of a postal questionnaire, its sensitivity to change over time, and how the use of such an instrument compares with retrospective perceptions of patients are all investigated. The review concludes with a brief discussion of future issues relating to the measurement of chronic pain severity, again from a research perspective. Expert Rev. Neurotherapeutics 3(5), 581–590 (2003) † Author for correspondence Dept. General Practice & Primary Care, University of Aberdeen, Foresterhill Health Center, Westburn Road, Aberdeen, AB25 2AY, UK Tel.: +44 (0) 1224 554 228 Fax: +44 (0)1224 550 683 a.m.elliott@abdn.ac.uk KEYWORDS: chronic pain, chronic pain grade, epidemiology, health services research, natural history, outcome assessment, pain, pain assessment, pain measurement, pain severity Chronic pain, unlike acute pain, is often mala- daptive and dysfunctional. Although it can arise without any obvious trigger (e.g., in the case of low back pain), it is commonly trig- gered by an injury or disease. Chronic pain is often perpetuated by factors other than the cause of the pain, including stress, environ- mental and affective factors; influences which also contribute to the intensity and persistence of the pain. T hus, rather than simply being an acute pain that persists, chronic pain is a com- plex multidimensional phenomenon involv- ing psychosocial, behavioral and pathophysio- logical processes, which produce both a sensory experience and a behavioral response [1]. Unlike acute pain, chronic pain often has no identifiable cause and its treatment is often complex. While the treatment of acute pain often needs to focus on its cause, the treatment of chronic pain also needs to focus on its effects [2]. Treatment of chronic pain is often lengthy and without cure. Until recently, knowledge of the epidemiol- ogy and natural history of chronic pain was limited, partly due to the lack of a gold stand- ard definition of chronic pain and problems of measuring chronic pain severity. Pain measure- ment is arguably one of the most challenging and difficult areas of health measurement [3]. Pain is a private and internal sensation that cannot be directly observed or measured, and measurement depends solely on the subjective response of the person experiencing it. Herein lies the very problem with pain measurement; we try to infer pain severity from the sufferers’ responses to it, yet the way pain is reported is influenced by many factors including biologi- cal, behavioral, social and psychological. Per- haps more than any other subjective measure- ment, reports of pain reflect the combined influence of the pain stimulus, environmental circumstances and the characteristics of the individual experiencing it. Despite the many problems with pain assess- ment, the measurement of pain and pain sever- ity is important and appropriate, acceptable, valid and reliable measurement instruments are needed. T he multidimensional assessment of pain began in the 1950s and a wide variety of pain measurement methods have been pro- posed to respond to the challenges of measur- ing pain. T he majority of these have evolved For reprint orders, please contact reprints@future-drugs.com