POS0518\u2005DIAGNOSTIC VALUE OF MUSCLE STRENGTH TESTS FOR THE DIAGNOSIS OF SARCOPENIA IN RHEUMATOID ARTHRITIS PATIENTS

Abstract

Motor disorders in patients with rheumatoid arthritis (RA) may be associated with sarcopenia (SP). The frequency of secondary SP in RA patients reaches 17 - 37% [1, 2]. Currently, in patients with RA muscle strength is evaluated by methods proposed in geriatric practice [3].To determine the sensitivity, specificity, diagnostic accuracy, positive and negative predictive value of handgrip strength (HS) and chair stand test (5-times sit-to-stand, CST) for the diagnosis of sarcopenia (SP) in women with rheumatoid arthritis (RA).87 women (aged 40-75 years) with RA were enrolled in the study. We did not include patients with aseptic bone necrosis, femoral and knee endoprostheses and comorbidity that negatively affected on the bone tissue. All patients underwent handgrip strength by mechanical dynamometer and CST. Handgrip strength less than 16\u2009kg and CST more than 15 seconds were the criteria for probable SP. Assessment of muscle mass was carried out by dual-energy x-ray absorptiometry («Discovery A» Hologic, USA). Reduced muscle mass was determined as a decrease in appendicular muscle mass (AMM) < 15\u2009kg or appendicular mass index (AMI) < 5.5\u2009kg/m2. Confirmed SP was diagnosed when there was a combination of low muscle strength and reduced muscle mass. For both tests of muscle strength assessment, the sensitivity, specificity, diagnostic accuracy of the method, as well as their positive and negative predictor value for the diagnosis of SP were calculated.Low handgrip strength and 5-times CST more than 15 seconds were found in 63 (72%) and 54 (62%) women, respectively. Among them only 20 (23%) patients had low AMM or AMI, so in these women SP was confirmed. For the handgrip strength the sensitivity of the method was 95%, and the specificity - only 34%, the diagnostic accuracy was 48%. The positive prognostic value of this test was 30%, and the negative value - 96%. The sensitivity, specificity and diagnostic accuracy of the CST were significantly lower than the handgrip strength and amounted to 50%, 21% and 28%, respectively. The prognostic value of this test, both positive (16%) and negative (58%), was also significantly lower than the assessment of handgrip strength in RA patients.We evaluated the diagnostic value of combination of two tests to identify individuals with probable SP: the sensitivity, specificity and diagnostic accuracy were 65%, 30% and 39%, respectively. Negative and positive predictive values were 71% and 24%, respectively, for combination of 2 tests, which was better than using only CST, but worse than using only hand dynamometry.Muscle strength tests proposed by the European Working Group on Sarcopenia in Older People have a low specificity, diagnostic accuracy and positive predictive values for detecting SP in RA patients, which requires the development of other methods of the first step of diagnosis of SP in RA patients.[1]Torii M, Hashimoto M, Hanai A, et al. Prevalence and factors associated with sarcopenia in patients with rheumatoid arthritis. Modern Rheumatology, 2018;29(4):589-595. doi:10.1080/14397595.2018.1510565[2]Vlietstra L, Stebbings S, Meredith-Jones K et al. Sarcopenia in osteoarthritis and rheumatoid arthritis: The association with self-reported fatigue, physical function and obesity. PLoS ONE, 2019;14(6):e0217462. doi:10.1371/journal.pone.0217462[3]Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Writing Group for the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), and the Extended Group for EWGSOP2. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019;48(1):16-31. doi:10.1093/ageing/afy169None declared