Self-assessment instruments: Development and validation

Introduction Negative symptoms are found in many patients with schizophrenia, but their assessment remains delicate. Standardized assessments are therefore needed to facilitate their identification. Many tools have been developed but most of them are assessments based on observer rating. Nevertheless, patient subjective evaluation can provide an additional outcome measure and allow patients to be more engaged in their treatment. Therefore, the aim of this study is to present past and recent tools assessing the subjective experience of negative symptoms; we will particularly focus on a novel tool, the Self-evaluation of Negative Symptoms (SNS). Methods Forty-nine patients with schizophrenia and schizoaffective disorders (DSMIV) were evaluated in order to demonstrate three components of the scale's validity: face and content validities and reliability. Results Cronbach's coefficient showed good internal consistency. Factor analysis extracted 2 factors (apathy and emotional). SNS was significantly correlated with the Scale of Assessment of Negative Symptoms and the Clinician Global Impression on severity of negative symptoms supporting good convergent validity. SNS scores were not correlated with level of insight, Parkinsonism, or with BPRS positive sub-scores in favor of good discriminant validity. Intra-subject reliability of SNS revealed excellent intraclass correlation coefficients. Conclusion This study shows good psychometric properties of SNS as well as quite satisfactory acceptance by patients. It also demonstrates the ability of patients with schizophrenia to accurately report their own experience. Self-assessments of negative symptoms should be used more in clinical practice since they might allow patients with schizophrenia to develop appropriate coping strategies.