Validation of smartphone-based assessments of depressive symptoms using the Remote Monitoring Application in Psychiatry (ReMAP)
Smartphone-based symptom monitoring has gained increased attention in psychiatric research as a cost-efficient tool for prospective and ecologically valid assessments based on participants self-reports. However, a meaningful interpretation of smartphone-based assessments requires knowledge on their psychometric properties; especially their validity. Here, we conducted a systematic investigation of the validity of smartphone-based assessments of affective symptoms by using the smartphone app Remote Monitoring Application in Psychiatry (ReMAP). Beck Depression Inventory (BDI), and single-item mood and sleep information was assessed via the ReMAP app and validated with stationary (non-smartphone) BDI scores and clinician-rated depression severity using the Hamilton Depression Rating Scale (HDRS). We found overall high comparability between smartphone-based and stationary BDI scores (ICC=.921, p<.001, n=173). Smartphone-based BDI further correlated with stationary HDRS ratings of depression severity (r=.783, p<.001, n=51). Higher agreement between smartphone and stationary assessments was found in affective disorder patients as compared to healthy controls, and anxiety disorder patients. Highly comparable agreement between delivery formats was found across age and gender groups. Similarly, smartphone-based single-item self-ratings of mood correlated with BDI sum scores (r=-.538, p<.001, n=168), while smartphone-based single-item sleep duration correlated with the sleep item of the BDI (r=-.310, p<.001, n=166). The present findings demonstrate that smartphone-based monitoring of depressive symptoms via the ReMAP app provides valid assessments of depressive symptomatology and therefore represents a useful tool for prospective digital phenotyping in affective disorder patients in clinical and research applications.