Zsa Zsa Weerts

Chapter 9 228 However, a low patient satisfaction would have likely led to a lower adherence and thereby a higher proportion of missing data. Therefore, it is unlikely that applying such a questionnaire would have altered our main findings. In conclusion, in this IBS drug trial, the use of a smartphone application as a digital symptom diary to assess treatment response was found to be highly feasible and resulted in high quality data-collection with an excellent patient adherence of more than 86% during the complete study period. The combination of the digital diary with the eCRF, planning tool and web-based-questionnaires in this study led to an overall standardized state-of-the art data-collection with excellent completeness and can be used as a framework for future RCTs. Due to the slight decrease in patient adherence to the digital diary throughout the study, caution is needed when using such methods in long-term studies. Although this framework was designed for IBS clinical trials, the results reported here are of added value for a far broader range of disorders for which the collection of PROMs is required. Future studies should preferably include a control group, for example a group using the IVRS or a group using the app without receiving reminding notifications, to compare adherence and to ascertain specific factors driving high adherence.