Patient-reported outcome data generated in a clinical intervention in community mental health care - psychometric properties

BACKGROUND DIALOG is an intervention to structure the communication between patient and key worker, which has been shown to improve patient outcomes in community mental health care. As part of the intervention, patients provide ratings of their subjective quality of life (SQOL) on eight Likert type items and their treatment satisfaction on three such items. This study explored the psychometric qualities of the outcome data generated in the DIALOG intervention to explore whether they may be used for evaluating treatment outcomes. METHOD Data were taken from 271 patients who received the DIALOG intervention. All patients were diagnosed with schizophrenia or a related disorder and treated in community mental health care. For SQOL and treatment satisfaction as assessed in the DIALOG intervention, we established the internal consistency (Cronbach's alpha), the convergent validity of SQOL items (correlation with Manchester Short Assessment of Quality of Life [MANSA]) and treatment satisfaction items (correlation with Client Satisfaction Questionnaire [CSQ]), the concurrent validity (correlations with Positive and Negative Syndrome Scale [PANSS]) and the sensitivity to change (t-test comparing ratings of the first and last intervention). We also explored the factorial structure of the eight SQOL items. RESULTS The internal consistency of the eight SQOL items was .71 and of the three treatment satisfaction items .57. SQOL scores were correlated with the MANSA (r = .95) and PANSS scores (general psychopathology: r = -.37, positive symptoms: r = -.27, negative symptoms: r = -.27). Treatment satisfaction scores were correlated with the CSQ (r = 0.36) and the PANSS (r = -.29, -.20, -.20). SQOL and treatment satisfaction score improved significantly over time. SQOL items loaded on two meaningful factors, one capturing health and personal safety and one reflecting other life domains. CONCLUSIONS The psychometric qualities of the SQOL scores generated in DIALOG are strong. The properties of the three treatment satisfaction items may be seen as acceptable. Although DIALOG has been designed as a therapeutic intervention, it can generate outcome data on SQOL and treatment satisfaction with acceptable psychometric qualities.