Prevention of Psoriatic Arthritis Inflammation Through Digital Care: A Feasibility Mixed-Methods Study

A validated 10-item questionnaire assessing ease of system use, scored on a 5-point Likert scale and converted to a 0-100 scale. A score ≥68 indicates above-average usability.

A structured heuristic tool assessing usability across seven domains (Basic System Performance, Task-Technology Fit, Interface Design, Navigation & Structure, Information & Terminology, Guidance & Support, Satisfaction). Results are presented as categorical ratings (Good, Moderate, Insufficient, Poor).

Number of eligible participants who agree to participate in the study.

Semi-structured focus group interviews

Count of steps collected unobtrusively from the smartwatch of patient to measure physical activity. Patients will wear the smartwatch daily

Accelerometer data collected unobtrusively from smartphone of patient and smartwatch to measure physical activity. Patients will wear the smartwatch daily

Number of disease flares self-reported by patients directly through the miPROLEPSIS application.

Count of disease flares reported using the structured Patient and Rheumatologist flare questionnaires developed in the iPROLEPSIS-PDPID study, completed during clinical visits.

Calculated as weight in kilograms divided by the square of height in meters (kg/m²). Used to classify nutritional status (underweight, normal weight, overweight, obesity).

Minimal Disease Activity status based on predefined criteria, determined from joint counts, pain, global activity, and function.

Composite disease activity score combining clinical and patient-reported variables. Total score ranges from 0 to 10; higher scores indicate more active disease. Low disease activity is defined as a score <3.2.

Composite score derived from tender joint count (0-68), swollen joint count (0-66), C-reactive protein level (mg/dL), patient pain (0-10 cm VAS), and patient global assessment (0-10). Higher scores indicate more active disease.

Validated patient-reported measure assessing disease impact across domains such as pain, fatigue, work, and emotional well-being

8-item scale measuring perceived self-efficacy in managing pain and other arthritis-related symptoms. Scores range from 10 to 100, with higher scores indicating greater self-efficacy.

9-item instrument for screening and measuring the severity of depressive symptoms in the previous two weeks. Score ranges from 0 to 27. Higher scores indicate more severe depressive symptoms

Self-reported questionnaire measuring the degree to which individuals perceive their life situations as stressful, over the past month. Scores are calculated by summing item responses, with higher scores indicating greater perceived stress.

Standardised questionnaire assessing assessing health-related quality of live across eight domains: physical functioning, role limitations due to physical health, bodily pain, general health perceptions, vitality, social functioning, role limitations due to emotional problems, and mental health. Scores are transformed to a 0-100 scale. Higher scores indicate better health status.

Self-reported physical activity levels across intensity domains (walking, moderate, vigorous), duration, and frequency over the past 7 days

20-item scale assessing difficulties in performing daily activities. Responses range from 0 (no difficulty) to 3 (unable to do). Higher scores indicate worse functional disability.

Questionnaire assessing adherence to Mediterranean dietary pattern. Score ranges from 0 to 14; higher scores reflect greater adherence.

Standardised instrument measuring quality of life across five domains: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Includes an index score and visual analogue scale (VAS).

Self-reported questionnaire measuring the degree to which health problems affect work productivity and regular activities. Includes absenteeism, presenteeism, and overall work and activity impairment.

Self-reported use of healthcare services, including visits to GPs and specialists.

Number of adverse events (AEs) and serious adverse events (SAEs).

Heart rate collected unobtrusively from smartwatch of patient. Patients will wear the smartwatch daily

Heart rate variability (HRV) collected unobtrusively from the patient's smartwatch to assess variations in heart rate. This is a feature provided by the smartwatch. Patients will wear the smartwatch daily.

Stress levels collected unobtrusively from smartwatch of patient to measure stress on a scale. This is a feature provided by the smartwatch. Patients will wear the smartwatch daily

Sleeping time (hours) collected unobtrusively from smartwatch of patient

Sleeping type (%) collected unobtrusively from smartwatch of patient

Images of hands and feet of the patient captured by the smartphone camera of the patient, to produce a feature vector relative to the condition of nails and joints of hands and toes resulting in an imaging digital biomarker

Videos of pre-specified movements of hand and body recorded by the smartphone camera of the patient, to produce a set of time series with landmark coordinates (obtained from the videos) resulting in an imaging digital biomarker

Physical activity intensity and physical activity categories collected unobtrusively from the smartwatch of patient to measure physical activity. Intensity and categories are features provided by the smartwatch. Patients will wear the smartwatch daily

Gyroscope sensor data for orientation collected unobtrusively from smartphone of patient

Keypad time-related data (e.g., inter-key press intervals) and associated metadata, collected unobtrusively from the patient's smartphone during app use, for fine motor function.

Number of discrete user sessions or app log-ins over the study period, indicating engagement consistency and sustained participation.

Dwell time within each application, i.e., duration of each user session, in minutes.

Number of times users access specific app features or modules, reflecting breadth and depth of feature engagement.

Ratio of the number of completed tasks to the number of abandoned or incomplete tasks

Ratio of the number of opened notifications to the number of resulting task completions

Time taken by users to complete a defined in-app task, in minutes.

Application) Ratio of the number of successful task attempts to the number of failed attempts (e.g., failed photo submissions or failed video tests).

Frequency and quantity of user-initiated data input, indicating active engagement and perceived app utility

Number of times healthcare professionals log into the iPROLEPSIS clinical dashboard

Estimated incremental cost (local currency) of implementing the iPROLEPSIS digital health tools vs. standard care, from a healthcare system perspective, including key cost drivers and sensitivity analyses.

Salivary DNA analysis

Stool analysis to extract bacterial DNA using 16S sequencing

Blood C-reactive protein levels (ml/L)

Waist circumference, measured in centimeters.

Descriptive clinical history collected at enrolment, including fulfilment of CASPAR classification criteria for psoriatic arthritis, psoriatic arthritis subtype, symptom onset date, diagnosis date, and comorbidities.

Descriptive characteristics collected at enrolment, including age, sex, nationality, ethnicity/race, marital status, household composition, education level, digital literacy, professional occupation/shift work, handedness and typing fingers used, birth history (mode of delivery: caesarean vs. vaginal), presence of family care/dependent responsibilities, dietary habits, alcohol consumption, and smoking status.

GRoC scale to evaluate change in disease activity.

Life events questionnaire for life events

Digital literacy questionnaire for technology readiness

Morning stiffness on a 10-point Likert scale. Higher scores indicate higher morning stiffness.

Air travel during the study period, including the occurrence, number, dates and purpose (vacation or work), as reported by participants.

Use of dietary supplements, including supplement type, dose, frequency, and duration of use, as reported by participants.

66/68 joint count for swelling and tenderness. Higher count indicates higher swollen/tender joints.

6 tendon count for enthesitis using Leeds Enthesitis Index

Physician-assessed measure of psoriasis severity and extent across four body regions (head, trunk, upper limbs, lower limbs), combining erythema, induration, and desquamation with area affected. Score ranges from 0-72; higher scores indicate more severe/extensive disease.

Physician-assessed measure of dactylitis severity, scored per digit (fingers and toes) on a scale from 0 (no dactylitis) to 3 (most severe). The total score is the sum across all assessed digits, yielding a possible total range of 0 to 60; higher scores indicate more severe dactylitis.

Self-reported life satisfaction (0-10).