On the use of the Positive and Negative Syndrome Scale in randomized clinical trials.

In the last 25 years, the Positive and Negative Syndrome Scale (PANSS) has been largely used to assess schizophrenia symptom intensity, but little information is available on how this scale was generally applied when evaluating the efficacy of schizophrenia therapies in randomized clinical trials. In the attempt to address this topic, a systematic PubMed Search was carried out using the keywords "PANSS" and "Randomized Clinical Trials". The analysis of retrieved articles highlighted that PANSS has constituted a suitable psychometric instrument to investigate the efficacy of pharmacological and non-pharmacological therapies. However, the information potentially provided by this scale was only partially reported in research articles, when characterizing the symptomatic features of patients at baseline. Furthermore, a consensus is needed to identify methodological strategies that may properly adapt PANSS-subscale structure with the symptomatic profiles of individuals enrolled in randomized controlled trials. The possibility that PANSS interview procedures and enrollment eligibility criteria may influence the symptomatic composition of patients involved in these studies is also discussed.