Randomized controlled trial to assess the effectiveness and cost-effectiveness of an intervention combining patient initiated care and telemonitoring through the online eHealth platform SpA-Net versus standard care for patients with spondyloarthritis.

Multicenter randomized controlled trial to investigate the effectiveness and cost-effectiveness of telemonitoring through SpA-Net, in combination with patient initiated care, versus standard care. Participants will be recruited at the outpatient clinics of participating centers, and will be randomised (after informed consent) into either the telemonitoring or standard care group. Patients in both arms will use SpA-Net and will be followed up for 1 year. Concomitantly a trial-based cost-utility analysis will be performed.

Randomisation (1:1; intervention versus standard care) is done using the minimisation method, stratifying for medical centre, subtype of SpA (axial, peripheral or combined) and treatment (biological use versus no biological use). Due to the nature of the intervention neither patients nor clinicians can be blinded to the allocation.

A sample size of 80 patients per group is necessary to detect the primary outcome with a power of 0.80 and alpha of 0.05. Assuming a 20% drop-out during follow-up, 100 patients per group will be included. This sample size also suffices to show non-inferiority for all secondary objectives with a power of 0.80 and a one-sided alpha of 0.025.

Study endpoints

A. The primary endpoint is defined as at least 25% reduction in the number of rheumatology department outpatient visits in the intervention group compared to the standard care group, within a 1-year follow-up period. Due to the COVID-19 pandemic these may also take place through telephone or video calls, replacing physical visits.

B. Secondary study parameters/endpoints

• Non-inferiority of telemonitoring compared to standard care with respect to quality of care and health outcomes.
• Non-inferiority with respect to experience with SpA-Net and general rheumatological care.
• Association between patient-reported self-management skills and successful application of telemonitoring
• Experience with telemonitoring through SpA-Net among care providers
• Difference between the populations with regard to healthcare cost per quality adjusted life year (QALY) gained after 1 year
• Difference between the populations with regard to societal cost per QALY gained after 1 year

STATISTICAL ANALYSIS The primary outcome will be analysed in the intention to treat (ITT) population. The differences between the two groups with respect to quality of care aspects and overall resource utilisation will be analysed in the ITT and the per-protocol (PP) population. All other secondary outcomes will be analysed in the ITT population.

The primary endpoint will be compared between both groups with ANOVA. Given that the population is randomised, an equal distribution of baseline characteristics is to be expected. In case differences between the two groups exist on baseline (visually), post-hoc analyses adjusting for these differences will be done (ANCOVA).

Secondary endpoints will be analysed with ANOVA. Post-hoc, subgroup analyses and predictive analyses with respect to self-management skills and and successful application of telemonitoring will be done with linear mixed-effect models with each endpoint as dependent variable and time, group and their interaction as fixed effects. Descriptive statistics will be used to summarize experience with telemonitoring among care providers.

Non-inferiority margins for secondary outcome measures:

• For ASDAS, non-inferiority is defined as an increase of no more than 0.9.
• A change in BASDAI of < 2.0 will be considered non-inferior.
• A cut-off of 20 millimetres is used for the patient global VAS, and a cut-off of 10 millimetres for the physician global VAS.
• An increase in VAS pain of no more than 20 millimetres will be considered non-inferior.
• At the time of the study proposal, approximately 90% of the patients is satisfied with the care provided. Non-inferiority is defined as a decrease of no more than 5%.

Health economic evaluation will be performed in accordance with the ISPOR guidelines, as well as the current Dutch guidelines for economic evaluations in healthcare. Analyses will be done both from a Dutch healthcare and societal perspective.

Currently, no consensus exists with regard to disease weights for SpA. As such, results will be reported for willingness-to-pay thresholds of both 20.000 and 50.000 euros per QALY gained. Sensitivity analyses will be performed to test the robustness of the results gathered.

Missing data will be addressed using multiple imputation.

Inclusion Criteria:

• Adult patient (18+ years)
• Diagnosis of SpA according to treating physician
• At least 2 years of disease duration, to be familiar with signs, symptoms, and medication
• Stable disease, defined as being in a patient acceptable symptom state according to patient AND treating physician AND no treatment change expected in the next few months
• Access to a computer, tablet and/or smartphone for the entire duration of the study

Exclusion Criteria:

• Insufficient mastery of Dutch language
• Incompetent to act for oneself
• Limited life expectancy
• Ongoing (or planned) pregnancy during the study period
• Patients participating in other research project(s)