Function is impaired during patient-reported idiopathic inflammatory myopathy flares - results from a longitudinal smartphone-based study

Background/Aims Idiopathic inflammatory myopathy (IIM) is a chronic autoimmune inflammatory disease characterised by myositis, thus impacting function and activities of daily living. Patients frequently refer to an exacerbation of IIM symptoms as a “flare”, however IIM flares have not been defined. High-frequency data collected via ubiquitous digital technologies, such as daily patient-reported outcome measurements, provide the opportunity to identify novel findings. This study aims to investigate associations between patient-reported IIM flares and function, thus characterising a priority area for patients. Methods The Myositis Physical Activity Device Study recruited a UK-based adult IIM cohort who completed weekly function and flare questions (i.e. every 7 days) via a specially designed smartphone-based app throughout a 13 week period in 2019/20. Weekly function questions, selected as priorities by a patient focus group from the Health Assessment Questionnaire, addressed carrying, exercise, socialising, reaching, and bending (4-point ordinal answers). A weekly flare question (binary “yes”/“no”) was also asked. The distribution of answers for function questions in participant-reported flare and non-flare weeks was calculated. Fisher’s exact test was used to determine whether there is a statistically significant difference between ‘flare’ and ‘non-flare’ weeks within each domain. Results Data on 21 participants (65% female) were collected across thirteen study weeks. In total, 1330 function questions and 266 flare questions were answered. 83 flare weeks and 183 non-flare weeks were reported. A lower proportion of answers across each function domain were answered as “without any difficulty” in flare weeks, compared to non-flare weeks (Table 1); the proportional difference was greatest for carrying and exercising. A higher proportion of answers across each function domain were answered as “with some difficulty” or “with much difficulty” in flare weeks, compared to non-flare weeks; the proportional difference was greatest for reaching and bending. Statistically significant difference (p-value <0.05, calculated via Fisher’s exact test) of all domains was observed between flare and non-flare weeks. Conclusion Functional impairment is associated with patient-reported IIM flare. The impact of flares upon activities of daily living highlights the need for further characterisation of IIM flares and the potential of patient-reported flares as a “digital biomarker” via smartphone-based app reporting. Disclosure G. Howard: None. N.S. Krogh: None. W. Dixon: None. H. Chinoy: None. A. Oldroyd: None.