ORIGINAL ARTICLE Handgrip Strength Test as a Complementary Tool in the Assessment of Fibromyalgia Severity in Women Virginia A. Aparicio, BSc, Francisco B. Ortega, PhD, Jose M. Heredia, PhD, Ana Carbonell-Baeza, PhD, Michael Sjöström, MD, PhD, Manuel Delgado-Fernandez, PhD ABSTRACT. Aparicio VA, Ortega FB, Heredia JM, Car- bonell-Baeza A, Sjöström M, Delgado-Fernandez M. Handgrip strength test as a complementary tool in the assessment of fibromyalgia severity in women. Arch Phys Med Rehabil 2011; 92:83-8. Objectives: To determine the ability of handgrip strength test to discriminate between presence and absence of fibromy- algia (FM) and FM severity in women. Design: A case-control study. Setting: Granada, south Spain. Participants: Women with FM (mean age  SD, n=81; 50.07y) and healthy women (mean age  SD, n=44; 47.76y). Interventions: Not applicable. Main Outcome Measures: Handgrip strength was mea- sured in both hands (average score was used in the analyses) by a maximal isometric test using a hand dynamometer. Patients were classed as having moderate FM if the score in the Fibro- myalgia Impact Questionnaire (FIQ) was less than 70 and as having severe FM if the FIQ was 70 or greater. Results: Handgrip strength levels were lower in patients with FM than healthy women (19.3 vs 27.9kg; P.001) and in women with severe FM (FIQ70) compared with those with moderate FM (FIQ70) (16.9 vs 20.2kg; P=.02). Receiver operating characteristic curve analyses revealed that the hand- grip strength threshold that best discriminated between the presence and absence of FM was 23.1kg (area under the curve [AUC]=.88; 95% confidence interval [CI], 0.82– 0.94; P .001), whereas the handgrip strength threshold that best dis- criminate between severe and moderate FM was 16.9kg (AUC=.67; 95% CI, 0.53– 0.80; P.05). Logistic regression analysis showed that handgrip strength 23.1kg or less was associated with 33.8 times higher odds (95% CI, 9.4 –121.5) for having FM after adjustment for age. In the FM group, handgrip strength 16.9kg or less was associated with 5.3 times higher odds (95% CI, 1.9 –14.5) for having severe FM. Conclusions: Handgrip strength is reduced in women with FM as well as those with severe FM from their peers with moderate FM. Identification of women who fail to meet the suggested standards can be a helpful and informative tool for clinician. Key Words: Fibromyalgia; Muscle strength dynamometer; Quality of life; Rehabilitation. © 2011 by the American Congress of Rehabilitation Medicine F IBROMYALGIA IS A condition characterized by the con- current existence of chronic, widespread musculoskeletal pain and multiple sites of tenderness. 1 In addition to pain and associated symptoms, activity limitations and functional im- pairment are common in patients with FM. 2,3 FM has an enormous impact on the patients’ health-related quality of life 4,5 because it limits activities of daily life such as walking and lifting and transporting objects. 4-6 Because of the complex nature of the disease, the assessment and monitoring of FM appears to be a dynamic process that still requires the contribution of new tools that facilitate the physi- cians’ daily work. 7 Alternative simple, practical, valid, and reliable clinical tools can be helpful in the clinical examination and evaluation of patients. It has been reported that muscular strength is decreased in people with FM compared with age-matched healthy peers. 8-12 Little is known, however, about the muscular strength differ- ences between patients with moderate and severe FM. In this context, handgrip strength is a quick and easy-to-perform mus- cular fitness test that provides useful information about overall muscular strength and could potentially be used in a clinical setting. Several studies have observed lower levels of handgrip strength in patients with FM, 13-17 which could be attributed to the following: (1) the patients with moderate or severe pain are likely to reduce their daily life physical activities and thus display a reduced muscular strength, 18 and (2) the fatigue and pain, characteristic of the FM, might negatively affect handgrip strength performance. 13 Both causes might contribute to ex- plaining the lower handgrip strength observed in patients with FM. On the basis of the same principles, we hypothesized that patients with severe FM would also have lower handgrip strength than those with moderate FM. From a clinical point of view, is interesting to examine the ability of the handgrip strength test to monitor the evolution of FM and discriminate between patients with moderate and severe FM. From the Department of Physical Education and Sport, School of Sports Sciences (Aparicio, Heredia, Carbonell-Baeza, Delgado-Fernandez), Department of Physiol- ogy, School of Medicine (Ortega), University of Granada, Granada, Spain; Depart- ment of Biosciences and Nutrition, Unit for Preventive Nutrition, NOVUM, Karo- linska Institutet, Huddinge, Sweden (Aparicio, Ortega, Sjöström). Supported in part by grants from the Spanish Ministry of Education (AP-2006- 03676 and EX-2008-0641), the Spanish Ministry of Science and Innovation (BES- 2009-013442), and the Swedish Heart-Lung Foundation (20090635). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organi- zation with which the authors are associated. Reprint requests to Virginia A. Aparicio, BSc, School of Sport Sciences, University of Granada, Carretera de Alfacar s/n 18011, Granada, Spain, e-mail: virginiaparicio@ ugr.es. 0003-9993/11/9201-00639$36.00/0 doi:10.1016/j.apmr.2010.09.010 List of Abbreviations ANOVA analysis of variance AUC area under the curve BMI body mass index CI confidence interval FIQ Fibromyalgia Impact Questionnaire FM fibromyalgia SF-36 Medical Outcomes Study 36-Item Short-Form Health Survey ROC receiver operating characteristic 83 Arch Phys Med Rehabil Vol 92, January 2011