THU0615-HPR FORCE-TIME CURVE ANALYSIS OF HANDGRIP STRENGTH IN PATIENTS WITH FIBROMYALGIA: COMPARISON WITH HEALTHY SUBJECTS
Authors: S. Farah, M. DI Carlo, F. Salaffi
Journal: Annals of the Rheumatic Diseases (2020)

Background: Factors associated with handgrip strength (HGs), in female with fibromyalgia (FM), use of force-time (FeT) curve to assess peak force, area under the curve (AUC), and variability of the time to reach maximum plateau of the curves (Fig.1) (1) to identify the impact of FM patients versus healthy controls have not been extensively studied. Figure 1. Force–time (FeT) curve showing the method of calculation of the various force attributes. Objectives: The aim of the study was to compare the HGs of FM with healthy subjects and to evaluate the relationship between curve characteristics and FM disease severity (2,3). Methods: One hundred and ten women (mean age 53.8±12.4 years; range 18 to 80) were included and compared with 111, age and BMI matched, female healthy controls. HGs was measured with an electronic device, while demographic and clinical characteristics of the subjects were obtained by the Revised version of the Fibromyalgia impact questionnaire (FIQR) and Fibromyalgia Activity Score (FAS). The patient opinion of their symptoms state (PASS) was evaluated as external criterion. The HGs threshold that best discriminates between the presence and absence of FM, as well as between moderate and severe FM, was determined using the receiver operating characteristic (ROC) curves analyses. Multivariate regression procedure was used in order to assess the relative contribution of the covariates on the HGs. Results: HGs-AUC and peak force levels were lower in patients with FM than healthy women (median 342.7 vs 496.5; and in Kg median was 13.9 vs 19.9, respectively; both at significant level of p&lt;0.001) and in women with severe FM compared with those with mild-moderate FM (p&lt;0.0001). The time to reach maximum plateau of the curves was significantly higher in patients with FM than healthy women (15.5 vs 11.8 sec; p&gt;0.001). ROC analyses revealed that the HGs peak force threshold that best discriminated between the presence and absence of FM was 14.2 kg (AUC 0.801; p&lt;0.001), whereas the HGs peak force threshold that best discriminate between PASS was 16.3 kg (AUC 0.834; p&lt;0.001). A negative correlation was found between FIQR and FAS scores and peak force, AUC in patients with FM (all at p&lt; 0.001). Furthermore, a correlation was observed between widespread pain index (WPI) and peak force, AUC (both at p&lt;0.0001), and of the time to reach maximum plateau of the curves (P=0.04) in patients with FM. Factors significantly associated with HGs-AUC in multivariate analysis were WPI and FIQR (both at p&lt;0.001). Conclusion: HGs is reduced in woman FM patients and is inversely related to FM severity and symptomatology. The FeT curve gave more information about grip in the FM and could be used as a complementary tool in the assessment and monitoring of FM. Further research on male FM patients is needed to confirm or contrast these findings. Table 6. Correlations between HGs curve characteristics and questionnaires studied through the Spearman’s rho correlation coefficients (rho). FIQR FAS HGs peak force levels Time to reach maximum plateau of the curves HGs-AUC WPI 0.732 &lt;0.0001 0.823 &lt;0.0001 -0.612 &lt;0.0001 -0.195 0.0415 -0.615 &lt;0.0001 FIQR 0.761 &lt;0.0001 -0.576 &lt;0.0001 -0.054 0.5768 -0.592 &lt;0.0001 FAS -0.577 &lt;0.0001 -0.167 0.0813 -0.588 &lt;0.0001 HGs peak force levels -0.151 0.0249 0.991 &lt;0.0001 Time to reach maximum plateau of the curves -0.135 0.0456 References: [1]Dias, J.J., Singh, H.P., Taub, N. &amp; Thompson, J. Grip strength characteristics using force-time curves in rheumatoid hands. J Hand Surg Eur Vol. 38 , 170-177 (2013). [2]Salaffi, F., Di Carlo, M., Arcà, S. &amp; Galeazzi, M. Categorisation of disease severity states in fibromyalgia: a first step to support decision-making in health care policy. Clin Exp Rheumatol . 36 , 1074-1081 (2018). [3]Aparicio, V.A., Ortega, F.B., Heredia, J.M., Carbonell-Baeza, A., Sjöström, M. &amp; Delgado-Fernandez, M. Handgrip strength test as a complementary tool in the assessment of fibromyalgia severity in women. Arch Phys Med Rehabil . 92 , 83-98 (2011). Disclosure of Interests: None declared