Handgrip strength test as a complementary tool in the assessment of fibromyalgia severity in women.

OBJECTIVES To determine the ability of handgrip strength test to discriminate between presence and absence of fibromyalgia (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 measured 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 Fibromyalgia 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 handgrip 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 discriminate 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.