Psychometric properties of the BASIS-24© (Behaviour and Symptom Identification Scale-revised) Mental Health Outcome Measure

Objective. Outcome measurement in mental health services is an area of considerable clinical interest and policy priority. This study sought to assess the Behaviour and Symptom Identification Scale-24 (BASIS-24(C)), a brief, patient self-reported measure of psychopathology and functioning, in a UK sample, including establishing population norms for comparative purposes. Methods. Participants were 588 adults recruited from psychiatric inpatient, outpatient and primary care settings; and 630 adults randomly sampled from primary care lists who completed the BASIS-24(C), and the Brief Symptom Inventory (BSI) at two time points. Results. BASIS-24(C) demonstrated adequate reliability (coefficient a values for combined clinical sample across subscales ranged from 0.75 to 0.91), validity and responsiveness to change (effect size for change of the BASIS-24(C) was 0.56 compared with 0.48 for BSI Global Severity Index). Population norms were established for the general population and adult in-patients (at in-take). The scale proved straightforward to complete across clinical settings. Variable rates of questionnaire distribution across clinical settings highlighted the ongoing challenge of incorporating outcome measures in clinical settings. Conclusion. BASIS-24(C) is a brief, easily administered, self-complete measure of mental well-being and functioning that adequately meets the requirements of reliability, validity and responsiveness to change required of an outcome measure.