We investigate whether meta‐data, specifically duration of responses to smartphone‐delivered surveys, is correlated to elevated scores on the depression assessment PHQ‐9 as well as the specific item around self‐harm (item 9).
In this observational study, we recruited 92 smartphone‐owning adults (≥ 18) with schizophrenia (45) and healthy controls (43). We installed an open‐source smartphone app called mindLAMP to collect survey results and latencies (response times) over a period of 3 months. Surveys were scheduled for twice a week, but participants were instructed to take the surveys naturally as much or as little as they wanted. A total of 1,218 PHQ‐9 surveys were completed across all participants over 3 months.
A total of 75 participants (39 with schizophrenia and 36 healthy controls) completed both the initial visit and follow‐up, as well as provided at least one self‐reported PHQ‐9 survey through the app. We found that depression symptom severity and response latencies were correlated for both individuals with schizophrenia (Spearman’s ρ = .22, p = .037) and healthy controls (Spearman’s ρ = .58, p < .001). Participants with schizophrenia scored higher (more severe) and took longer for every item of the PHQ‐9 when compared to controls (p < .05 for each item). Item 9 response value and latency was slightly correlated for participants with schizophrenia (Spearman’s ρ = .086, p = .035) but was not significant for controls (Spearman’s ρ = .036, p = .37).
Meta‐data revealed group differences between individuals with schizophrenia and healthy controls based on individual depression symptoms completed on a smartphone. Correlation between suicide specific question latency and severity for participants with schizophrenia but not for controls indicates the clinical potential and need for further research.