Validity and psychometric properties of the Self-Identification as Having a Mental Illness Scale (SELF-I) among currently untreated persons with mental health problems

Conceptualizing own symptoms as potential signs of a mental illness is an important, yet under-researched step towards appropriate help. Few validated measures address recognition and identification of own mental illness. Aim of this study is to investigate performance and correlates of the 'self-Identification as Having a Mental Illness’ scale (SELF-I) in a group of 229 currently untreated individuals with mental health problems, predominantly depression. Measures included: self-identification with having a mental illness (SELF-I), depressive and somatic symptom severity (PHQ-9 and PHQ-15), illness perceptions (B-IPQ-R-C), and sociodemographic variables. Principal-component analysis revealed in a unidimensional factor structure. The SELF-I showed good reliability in terms of internal consistency (Cronbach's alpha, 0.85–0.87) and re-test reliability over three months (Intraclass correlation coefficient, 0.74). Associations with depressive symptoms, previous treatment experiences and self-labelling demonstrated construct and criterion validity. Low associations with somatic symptoms and with illness-perceptions as measured by the B-IPQ-R-C indicated discriminant validity. We did not observe any floor or ceiling effects. The SELF-I scale is a brief, unidimensional and reliable measure of self-identification as having a mental illness that offers useful research perspectives.