Abstract
BACKGROUND: The Maudsley 3-item visual analogue scale (M3VAS) was developed as a novel and intuitive patient-reported measure for depression, focusing on core symptoms and suicidality. AIMS: To evaluate the longitudinal validity of M3VAS for capturing symptom change over time. METHOD: Both M3VAS and the Patient Health Questionnaire (PHQ-9, as reference standard) were administered in an observational study (RHAPSODY, no. NCT04939818) at weeks 0, 2 and 4 to both depressed patients (n = 50) and matched controls (n = 24). We serially tested factor structure, internal consistency and convergence (correlation) over time, assessing responsiveness by both correlation of change in score and effect of time across scales (analysis of variance and effect size). RESULTS: M3VAS exhibited strong factor loadings and high item interrelatedness (Cronbach's alpha 0.78-0.83) at all time points. Total scores correlated strongly with PHQ-9 at each time point (r > 0.8, P < 0.001). Correlation of score change over the study period (r = 0.65, P < 0.001) also confirmed responsiveness. In the depressed group, an effect of time on score was seen for both M3VAS (F = 4.942, P = 0.010) and PHQ-9 (F = 12.505, P < 0.001), with standard response mean (Cohen's d) of 0.58 and 0.74, respectively. No effect of time was seen in the control group. CONCLUSIONS: Following previous cross-sectional validation against the Quick Inventory of Depressive Symptomatology-Self-report, this present study demonstrated appropriate longitudinal measurement properties for M3VAS as a measure of depression, including responsiveness. Evaluating the ability of M3VAS to discern responses with a variety of treatments is a key future goal.