PECC--factor structure and findings in three longitudinal cohorts of patients with schizophrenia.

Background: Symptom control by drug treatment is the most important task in routine clinical care of patients with schizophrenia. Structured assessment methods are needed in this task but not used much. The US-developed Positive and Negative Syndrome Scale (PANSS) is a standard tool for symptom assessment. The Psychosis Evaluation tool for Common use by Caregivers (PECC) was constructed in Europe some years ago, with the intent to overcome some of the PANSS drawbacks. Aims and methods: To validate PECC on three longitudinal cohorts of schizophrenic patients representative of Swedish outpatients (n = 225, six assessments over 5 years), international forensic patients (n = 186) and matched non-forensic controls (n = 116), five assessments over 2 years for both. Results : The factor structure of PECC appears to be highly robust. Norm values (in percentiles) were calculated on the materials. Such data provides for analyses of symptom profiles and improvement over time measured in absolute numbers. Forensic patients appear to have a much lower symptom load (except for cognitive symptoms) than the other groups. Forensic controls had much shorter inpatient times than any other group and never caught up with respect to symptom control, even after 2 years. These differences suggest that the scale is clinically valid. Conclusion: PECC has a more robust factor structure than PANSS and is simpler to use. Percentile norms have been constructed for outpatients with schizophrenia in general and forensic psychiatry. Percentile scores are accessed readily by the net. PECC is available in many languages. Its separate self-harm item may improve assessments of suicide risk among patients with schizophrenia.