Reliability and accuracy of scores using 10-or 20-item short forms of the positive and negative syndrome scale (panss) replicated in 3 large outpatient trials

Most pediatric psychosis studies use the Positive and Negative Syndrome Scale (PANSS) as the primary outcome measure and use Cronbach’s alpha to measure its reliability. Alpha has major limitations, including assuming that a single factor underlies the total score, whereas multiple studies have found 5 weakly correlated factors underlying the 30 items. Only 2 of many PANSS short forms have preserved the 5-factor coverage, and no publication to date has looked at patient-level score accuracy using methods widely used in some areas of medicine. We addressed these gaps by using a newer reliability method, omega, to model the multifactor structure directly, as well as using Bland-Altman methods to compare the accuracy of the scores of the 10- and 20-item short forms vs the 30-item version.