Toward digitally supported self-assessment of patients with idiopathic inflammatory myopathies

Manual muscle testing (MMT8), the current gold standard for assessing muscle function in patients with idiopathic inflammatory myopathies (IIM), has notable limitations. This study had three aims (1) to compare MMT8 with inertial sensor-based gait analysis, (2) to evaluate patient-performed functional tests guided by shared decision-making (SDM), and (3) to investigate adherence to electronic patient-reported outcomes (ePROs). Gold standard muscle function assessment (MMT8) was performed at baseline (T0) and three months (T1). Additionally, inertial-sensor-based gait analysis was completed at T0 and two standardized upper extremity (Modified Barré test; 10-time arm lift test) and two lower extremity muscle endurance tests (60-second Sit-to-Stand (STS) test; Mingazzini test) were presented to patients to choose from. Through shared decision-making, each patient selected one test for lower and upper extremities and opted to record weekly results on paper or through a medical app. Correlations between gait parameters, functional tests, and MMT8 were analyzed, while agreement between patient- and healthcare professional (HCP)-recorded results at T0 and T1 was assessed. Responsiveness to change was also evaluated. A total of 28 IIM patients (67.9% female; mean age 57.4 ± 12.9 years) were enrolled. Moderate correlations were observed between gait parameters and MMT8, such as walking speed (r = 0.545, p = 0.004) and stride length (r = 0.580, p = 0.002). All patients selected the Modified Barré test for assessing upper extremity function and 60.7% of patients chose the Mingazzini test for lower extremity function. Agreement between patient- and HCP-recorded functional test results was excellent at baseline and after three months (ICC 0.99–1.00). Functional tests demonstrated strong correlations with MMT8, particularly for the Mingazzini test (r = 0.762, p = 0.002). Patients preferred app-based recording (82.1%) over paper-based methods and weekly ePROs were completed on average 6.9 out of 12 weeks (57.5%). Patient-performed functional tests are reliable, scalable alternatives to MMT8, with gait analysis providing complementary insights. Digitally supported self-assessments can enhance clinical workflows, remote monitoring, and treat-to-target strategies, empowering patients and improving disease management.