Clinical Significance of Reported Changes in Pain Severity☆,☆☆,★
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INTRODUCTION
Investigators involved in pain research commonly use visual analog scales to measure pain severity and pain relief.1 Among other advantages, visual analog scales offer ease of use in a variety of settings and can be administered with a minimum of training. Visual analog scales are sensitive to treatment effects, and their data can often be analyzed with parametric statistical techniques.2 The latter characteristics are particularly important to investigators seeking a powerful assessment tool
MATERIALS AND METHODS
A prospective, descriptive study of the acute pain experience was conducted in an urban county hospital ED with a Level I trauma center. The study protocol was approved by the Emory University Human Investigations Committee.
The study was conducted on eight nonconsecutive days in December 1994 and January 1995 when research assistants were available. Between the hours of 10 AM and 6 PM, ED patients 18 years of age or older who had trauma with complaints of pain were enrolled in the study.
RESULTS
Forty-eight patients were enrolled; they produced a total of 248 pain contrasts, for a mean of 5.2 pain contrasts per subject. Thirty-two patients completed the maximum number of six contrasts. Characteristics of the study group and their injuries are detailed in Table 1. Initial pain severity scores varied over the entire 100-mm range, with a slight skew toward more severe scores, as shown in Figure 1. Mean and median initial pain scores were 56 mm and 60 mm, respectively.
DISCUSSION
Others have attempted to determine the minimum clinically important difference for a variety of assessment instruments, including quality of life measures for chronic heart and lung disease, rheumatoid arthritis, and other arthritic conditions.4, 5, 6 The basic approach in these studies has involved referencing differences in instrument scores to categorical ratings of changes in health status. For example, patients may be asked to rate themselves using an instrument and then to compare their
References (8)
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Measurement of health status: ascertaining the minimal clinically important difference
Control Clin Trials
(1989) Scaling clinical pain and pain relief
Parametric statistics for evaluation of the visual analog scale
Anesth Analg
(1990)- et al.
Clinical Epidemiology: A Basic Science for Clinical Medicine
(1991)
Cited by (0)
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From the Division of Emergency Medicine, Department of Surgery, Emory University School of Medicine, Atlanta, Georgia.
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Address for reprints: Knox H Todd, MD, MPH, Center for Injury Control, Rollins School of Public Health of Emory University, 1518 Clifton Road Northeast, Room 254, Atlanta, Georgia 30322, 404-727-1265, Fax 404-727-8744
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Reprint no. 47/1/69723