Clin Rheumatol (2005) 24: 266-271 DOI 10.1007jsl0067-004-1003-7 ORIGINAL ARTICLE A. P. Marques' E. A. G. Ferreira . L. A. Matsutani C. A. B. Pereira . A. Assumpção Quantifying pain threshold and quality of life of fibromyalgia patients Received: 7 May 2004 j Accepted: 15 September 2004 j Published online: 23 December 2004 © Clinical Rheumatology 2004 Abstract The most typical symptom of fibromyalgia (FM) is diffuse pain, and pain at specific points-tender points-is crucial for its diagnosis. By comparing heal- thy individuaIs and FM patients, this study was aimed at assessing pain and quality of life of Brazilian females with FM, while seeking for a correlation between pain threshold and quality of life. A total of 178 women were evaluated: 124 were FM patients and 54 were healthy women. Pain threshold at tender points was quantified by dolorimetry, and diffuse pain by means of the visual analogue scale (VAS); the Fibromyalgia lmpact Ques- tionnaire (FlQ) was used to evaluate quality of life. Statistical treatment of the data allowed for proposing two indexes: a pain threshold index (PT) and a quality of life one (QOL). PT is the lowest value among all pain thresholds measured at the 18 tender points; QOL is the mean of responses to the FlQ and VAS. Both indexes were tested and showed significant differences between the test and control groups. By pairing pain threshold values of each tender point in the test and control groups, it was found that the most sensitive points matched between the two groups, that is, the most sensitive anatomic spots in a healthy individual are also likely to be the most sensitive points in a person with A. P. Marques (12]) Department of Physical, Speech, and Occupational Therapy, School of Medicine, University of São Paulo, Rua Cipotânia 51, Cidade Universitária, São Paulo, 05360-160, Brazil E-mail: pasqual@usp.br E. A. G. Ferreíra Department of Physícal Therapy, Methodíst Uníversity, São Paulo, Brazíl L. A. Matsutaní Department of Physical Therapy, FIEO Uníversíty, São Paulo, Brazíl C. A. B. Pereira lnstitute of Mathematics and Statistics, Universíty of São Paulo, São Paulo, Brazil A. Assumpção School of Medícíne, Uníversíty of São Paulo, São Paulo, Brazil FM. This suggests that a stimulus that provokes slight discomfort to a healthy person may produce more pain in FM patients-which may bear implications for FM clinical treatment. ln this sample of Brazilian women, FM patients had both lower pain threshold and worse quality of life than healthy women. Keywords Fibromyalgia' lndexes . Pain threshold . Quality of life . Tender points Introduction Fibromyalgia (FM) is a rheumatic syndrome charac- terized by diffuse muscle pain, low pain threshold in at least 11 tender points (of 18 over the body), and a series of associated symptoms such as fatigue, sleep distur- bance, anxiety, morning stiffness [1, 2], and dyspnea in some cases [3-5]. This syndrome affects mostly women of reproductive age, interfering in their quality of life [6, 7]. The main complaint of patients with FM is diffuse pain; the most striking feature is the increase in pain sensitivity at tender points (TP). These are anatomically specific, located at tendons or in the ventral part of muscles, as determined by a study of the American College of Rheumatology (ACR) that became the criteria for FM classification [8]. For health providers, pain is difficult to measure, partly because of the individual judgment of stimuli intensity [9]. Several methods are used to evaluate intensity of pain as reported by the patient such as the visual analogue scale (VAS) [10], body maps [11], and the McGill Pain Questionnaire [12]. Some methods have been proposed to quantify pain sensitivity at tender points in patients with FM. According to Russel [13], there are three kinds of eval- uation: (1) numerical counting of sensitive tender points, (2) pressing TP using the digit pressure technique, and (3) assessing the mean pain threshold through pain