Patient reported outcome for physical function in idiopathic inflammatory myopathy.

Objectives: There is an unmet need to develop patient-reported outcomes (PRO) measures for Idiopathic Inflammatory Myopathies (IIM). To investigate the feasibility, compliance, and psychometric properties of NIH's Patient-Reported Outcomes Measurement Information System (PROMIS) physical function-20 (PF-20) in a large U.S. IIM population.

Methods: "Myositis Patient Centered Tele-Research" (My PACER) is a multicentre prospective observational study of IIM patients, competitively recruited through traditional in-person clinic visits (Center-Based Cohort [CBC]), and remotely using smartphone and web-based technology (Tele-Research Cohort [TRC]). The CBC was further randomly divided (1:1 ratio) into a traditional local sub-cohort, and a remote sub-cohort. Data collected included PRO and other patient self-assessments monthly for 6 months. Clinician-reported outcomes were obtained at baseline and 6 months.

Results: 120 IIM patients were enrolled (82 TRC/38 CBC, mean age 55 ± 13.4, 75% females, 81% Caucasians), with similar demographics and mean PROMIS PF-20 score between cohorts. The PROMIS PF-20 score was not associated with age, sex or race. The compliance and completion rates were similar between TRC and CBC as well as sub-cohorts. PROMIS PF-20 showed strong test-retest reliability at 1 month. PROMIS PF-20 was significantly associated with all core set measures except extra-muscular global and CK, as well as with most of symptoms, function and physical activity measures. PROMIS PF-20 illustrated concordant change with myositis response criteria and patient assessment, with a large effect size.

Conclusions: PROMIS PF-20 demonstrates favorable psychometric properties including reliability, validity and responsiveness in a large cohort of myositis patients, with similar adherence in local or remotely enrolled patients.