Agreement between patient-reported outcome measures collected via a smartphone application vs a touchscreen solution in an outpatient clinic among patients with inflammatory arthritis: a randomised, within-participant trial

Background: Patient-reported outcome measures (PROMs) are essential to understand the patient’s perception of arthritis activity. In Demark, PROMs are registered on a touchscreen in the outpatient clinic. However, some patients find it inconvenient due to e.g. waiting in queue, lack of privacy, uncomfortable seating position, reduced upper limb strength and dexterity with seeing the touchscreen due to deformity of the cervical spine. The widespread use of smartphones makes it possible for patients to register PROMs via an application (app) on their own device.Objectives: The primary aim is to evaluate the agreement (i.e. similarity) between the two devices assessed by the Health Assessment Questionnaire Disability Index (HAQ-DI) status among patients with inflammatory arthritis.Methods: The study was a randomised, crossover, agreement trial (NCT03486613) conducted at Aalborg University Hospital, Denmark. Participants were recruited through an invitation on the touchscreen in the outpatient clinic. Patients with an established diagnosis (>= 12 months) of rheumatoid arthritis (RA), psoriatic arthritis (PsA) or axial spondyloarthritis (axSpA) and experience with the PROM questionnaires (>= 3 previous registrations) were enrolled and randomised in ratio 1:1 (stratified by diagnosis) to PROM registration through the DANBIO app and the touchscreen in random order. Figure 1A and 1B shows the two devices.The sample size calculation was based on a prespecified equivalence margin of textpm0.11 HAQ-DI points (i.e.