Concordance between chart review and structured interview assessments of schizophrenic symptoms

BackgroundIt is unclear whether direct structured interviews are able to capture the full range of psychopathology in schizophrenia, as is required in diagnostic assessments or clinical ratings. We examined agreement between symptom ratings derived from direct patient interviews and from review of casenotes.MethodsThe study sample comprised 1021 schizophrenic subjects collected as part of the Irish Case-Control Study of Schizophrenia. Diagnostic interviews used a modified version of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition. Symptoms were rated by the interviewer. In addition, the Casenote Rating Scale was used to rate symptoms based on medical record information. For each negative and positive symptom, we calculated the Pearson correlation between the interview and the casenote rating. Using the mean of the interview and casenote rating for each symptom, exploratory factor analysis using Varimax rotation was performed.ResultsThree factors were extracted in factor analysis: positive, negative, and Schneiderian symptoms. The highest correlations between interview and casenote ratings were for negative symptoms, in which all symptoms were significantly correlated. Positive and Schneiderian symptoms were significantly correlated with the exception of thought insertion, thought withdrawal, voices speaking in sentences, and somatic hallucinations. Significant correlations were generally moderate (0.2-0.55).ConclusionMost schizophrenic symptoms, especially negative symptoms, can be assessed by direct interviews as the sole source of information with moderate reliability. However, the presence of some Schneiderian and possibly less prevalent positive symptoms may be difficult to determine without a review of records, which may include longitudinal observations and information from multiple observers.