Is the PANSS used correctly? a systematic review

<p>Abstract</p> <p>Background</p> <p>The PANSS (Positive and Negative Syndrome Scale) is one of the most important rating instruments for patients with schizophrenia. Nevertheless, there is a long and ongoing debate in the psychiatric community regarding its mathematical properties.</p> <p>All 30 items range from 1 to 7 leading to a minimum total score of 30, implying that the PANSS is an interval scale. For such interval scales straightforward calculation of relative changes is not appropriate. To calculate outcome criteria based on a percent change as, e.g., the widely accepted response criterion, the scale has to be transformed into a ratio scale beforehand. Recent publications have already pointed out the pitfall that ignoring the scale level (interval vs. ratio scale) leads to a set of mathematical problems, potentially resulting in erroneous results concerning the efficacy of the treatment.</p> <p>Methods</p> <p>A Pubmed search based on the PRISMA statement of the highest-ranked psychiatric journals (search terms "PANSS" and "response") was carried out. All articles containing percent changes were included and methods of percent change calculation were analysed.</p> <p>Results</p> <p>This systematic literature research shows that the majority of authors (62%) actually appear to use incorrect calculations. In most instances the method of calculation was not described in the manuscript.</p> <p>Conclusions</p> <p>These alarming results underline the need for standardized procedures for PANSS calculations.</p

Evolutionary origin of a monophasic Salmonella serovar, 9,12:l,v:-, revealed by IS200 profiles and restriction fragment polymorphisms of the fljB gene.

The emergence in several countries of the monophasic serogroup D1 serovar Salmonella 9,12:l,v:- provided the opportunity to study its evolutionary origin. According to current models, such a variant serovar could have arisen by horizontal transfer of a new flagellar gene to a preexisting monophasic Salmonella strain or, alternatively, by the loss of the phase 2 flagellar gene of an originally biphasic Salmonella strain. Five known serovars of Salmonella, S. panama, S. kapemba, S. goettingen, S. zaiman, and S. mendoza, could have been possible ancestors of the new variant. The profiles of the insertion element IS200, which has been shown to provide phylogenetic markers for serogroup D1 salmonellae, were analyzed in relation to the restriction fragment length polymorphisms of the phase 2 flagellar gene. Together they provide unequivocal evidence that Salmonella 9,12:l,v:- arose from a strain of S. goettingen. Analysis of the flj operon of the variant indicated that loss of phase 2 flagellar antigen expression occurred through deletion of the hin gene and adjacent DNA, thereby blocking the phase 2 flagellar gene in the off position