Predictors of functional impairment at assessment and functional improvement after treatment at a national digital mental health service.

Mental disorders are associated with impairment to daily functioning, which affects both the individual and society. Despite this, most research on treatment outcome only report symptom change. Self-reported days out of role (DOR) is a simple measure of functional impairment used in many population studies. The current study sought to report on the degree of functional impairment measured by DOR in a clinical sample at assessment, the factors associated with this impairment, the predictors of functional improvement after treatment and the relationship between symptomatic and functional change. Using a prospective uncontrolled observational cohort study design with a sample of 17,813 patients accessing a digital mental health service (DMHS), we examined self-reported demographic, psychosocial and clinical data. Using a series of univariate regression models and multivariate classification algorithms, we found that baseline DOR was associated with age, employment and relationship status, symptom severity, symptom chronicity and with the presence of several psychosocial difficulties. Baseline DOR was best predicted by older age, disability payments, higher symptom severity and increasing number of endorsed psychosocial difficulties (R2 = 32.7 %). Forty-one per cent of the sample experienced a >50 % or greater reduction in DOR following treatment. Those who were separated, unemployed or on disability payments, or with severe and chronic depression, experienced the greatest reductions in DOR after treatment. Changes in functioning were independent of changes in symptoms, highlighting the importance of functional impairment as a treatment outcome. This study found that many of the patients who access DMHS have significant levels of functional impairment, a large proportion obtain functional improvement after treatment, and improvement in function after treatment was independent of improvement in symptoms.