Validation of the Bech-Rafaelsen Mania Scale using latent structure analysis

The essential criteria of internal validity have not been sufficiently evaluated for any mania rating scale, although the fulfillment of such criteria is a prerequisite for summing the item scores to give a total score reflecting the severity of mania, and for comparing total scores across patient groups that differ with regard to variables such as age and sex. This study investigated the internal validity of the Bech-Rafaelsen Mania Scale (MAS), based on the ratings of 100 consecutively admitted drug-free DSM-III-R manic patients. Application of logistic latent structure models did not statistically confirm the additivity of the MAS. However, a modified MAS (the MAS-M) arising from the analyses fulfilled the measurement model. Transferability of the MAS-M across age and sex was also confirmed. The MAS-M showed an acceptable concurrent validity and an adequate sensitivity in discriminating between responders and non-responders among patients participating in a drug trial. The MAS-M presented here is the first mania rating scale that has been shown to fulfil statistical criteria for internal validity.