The hypothesis of this thesis was that patient initiated care (PIC) with self-monitoring symptoms in an app would safely reduce costs and save time in patients with rheumatoid arthritis (RA). Furthermore, the thesis describes the development of the app and its feasibility, explores (facilitators and barriers to) ePRO completion/adherence and the relationship between ePRO results and clinical parameters. Our results show that while PIC with self-monitoring is safe and reduces the number of visits, it does not lead to lower costs from a societal perspective. Despite not being of lower costs, the intervention, and PIC interventions in general, might still be useful. We could consider implementation of the intervention as it is of similar cost as usual care, and requires less consumption of time for rheumatic healthcare providers and patients. This will be increasingly important in the coming years due to the growing shortage of healthcare personnel.(5,6) However, the number of visits with other healthcare providers following the intervention should be monitored, as there was a trend to visit other healthcare providers more often following the intervention. Furthermore, the intervention might be of particular interest to regions/countries where there are long(er) waiting lists and more rural areas with a high average travel time to rheumatology clinics. This thesis also shows that self-monitoring is feasible, and we have identified several barriers and facilitators to ePRO completion that could improve adherence to self-monitoring. Rheumatologists should discuss results and allow patients to skip visits when the scores are low (to maximize adherence). With focus groups, we should evaluate why not all rheumatologist discuss results, so that their barriers for discussing results can be understood and possibly taken away with specific instructions that address their hesitations (which we do not know yet). These instructions should also make rheumatologists (more) aware of their important role in ePRO completion. Our results indicate that patients could skip their visit safely if their ePRO results are low. Patients that have low scores on their RAPID3 (