A comparison of pain measures used with patients with Fibromyalgia.

Bigatti, S. M., & Cronan, T. A. (2002). Journal of Nursing Measurement, 10(1), 5-13.

Fibromyalgia syndrome (FMS) is a painful and debilitating chronic condition of unknown etiology that primarily affects the musculoskeletal system of women and persons over age 40. Its dominant features include pain, fatigue, stiffness, disrupted sleep patterns, irritable bowel syndrome, anxiety, and depression (Bennett, 1996). The effect of these symptoms can lead to reduced functioning and disability. The diagnosis is often difficult and frustrating for patients and healthcare providers because there is no generally accepted biologic marker for FMS and the diverse symptoms require a long process of excluding other disorders. Because there is no cure, the focus is placed on managing symptoms, especially pain. Pain is the main complaint and, thus, the main treatment concern.

The purpose of the study was to evaluate instruments used to assess pain and determine which was most useful in terms of validity, ease of administration, and scoring. In all, six scales were used: three measured pain and three measured related aspects of well-being. The pain scales were: (1) McGill Pain Questionnaire (MPQ), widely used to measure pain in chronic pain populations and its three subcales: the Pain Rating Index (PRI), a measure of the sensory qualities and cognitive-affective characteristics of pain perception; the Present Pain Index (PPI), a measure of pain intensity; and the Number of Words Chosen Index (NWC), where participants select a word from each category only when they find a word that describes their pain, and the number of words subjects choose is used as a measure of the perceived pain intensity; (2) Manual Tender Point Exam (TPE), where participants are asked how much pain (on a scale from 1 to 10) they feel when the examiner manually applies 4 kg of pressure to each of 18 possible sites; and (3) Visual Analog Scale (VAS), a widely used pain evaluation instrument based on a straight line (10 cm long), scaled from 0 to 100, on which the patient marks the intensity of his or her pain. Other instruments included: (1) Arthritis Self-Efficacy Scale, with its three subscales (pain, functions, and symptoms), which measures perceived self-efficacy; 2) Fibromyalgia Impact Questionnaire, which measures physical, psychological, social, and global well-being; and 3) Pittsburgh Sleep Quality Index (PSQI) used to measure various aspects of sleep quality.

The idiopathic chronic pain of patients with FMS has a strong psychological component. The VAS showed the highest correlations with measures of pain, fatigue, and stiffness. The VAS also has the advantage of being quick, concise, and easy to administer and score. Participants in the study felt comfortable and competent in indicating their pain on the VAS. However, a few words of caution must be added. The line must be free of marks that could possibly imply intervals of some sort, and the choice of words used for the anchors could sway where on the line the individual marks their pain.

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