Background/Purpose: Inflammatory myositis are heterogenous group of diseases affecting skeletal muscles and multiple different organs. Assessing improvement in disease activity is done by Manual muscle testing (MMT) and Functional index 2(FI-2). These are time taking and need expertise to administer. Several Timed function tests (TFTs) like the 2- minute walk test (2MWT) or 30s raise from a chair test and 30s 1kg arm rise test may be better alternatives and less time taking. Moreover these tests can be self-administered by patients themselves. In the current world of accountability for treatment response and improvement in technology, these TFTs upon self-administration in particular time intervals have the potential to provide objective data on diseases status enabling the physician to make therapeutic decisions. We undertook a study with objective to evaluate the performance of TFT in assessing muscle diseases at baseline and to evaluate the performance of TFTs to detect change in muscle power and endurance with treatment.

Methods: This is an observational cohort study which included 29 patients with polymyositis and dermatomyositis satisfying ENMC classification criteria. Patients with inclusion body myositis, overlap myositis, chronic kidney disease, coexisting myocarditis, sepsis, malignancy, pregnancy were excluded. MMT8, FI-, EQ-5D and Timed function tests were done at baseline and after 3 months.  

Results: The study had 29 patients of which 6 were polymyositis and 23 were dermatomyositis. Male to female ratio was 1:2.1. Anti-cell antibody was positive in 20 patients. Out of 29 patients, 11 had active disease and rest 18 had stable disease. Mean scores of MMT8, Fi-2 and TFTs are shown in table 1. The 3 TFTs had moderate to high correlation with MMT8 and FI-2 at baseline in inactive disease group but only with FI-2 in active disease as shown in Table 2. At 3 months, change in all 3 TFTs significantly correlated with change in Fi-2 in active disease, but in stable disease only 2MWD had moderate correlation with MMT8. (Table 3)

Conclusion: 2 Minute walk distance is a better alternative to the conventional muscle testing as it measures both power and endurance. This score can overcome the ceiling effect of MMT-8. Besides, owing to the ease of administration 2MWD may be used as a patient reported outcome measure in IIM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/two-minute-walking-distance-and-other-timed-function-tests-are-superior-to-mmt-8-in-assessing-outcomes-in-polymyositis-and-dermatomyositis/