Cognitive screening tools in multiple sclerosis revisited: sensitivity and specificity of a short version of Rao's Brief Repeatable Battery.

Background: Cognitive deficits are common in multiple sclerosis (MS) and require continuous monitoring. In routine examinations, screening instruments such as the Brief Repeatable Battery (BRB) may serve this purpose. It was suggested that even a shortened version of the BRB, comprising the Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test (PASAT) and Selective Reminding Test (SRT), may be feasible. However, an evaluation of sensitivity and specificity of the short BRB in comparison to an independent battery of established tests has not yet occurred. Therefore in the current study, this short version of the BRB was matched against the gold standard of an extensive test battery comprehensively assessing neuropsychological functions.
Methods: 127 MS-patients were tested with a short version of the BRB and an extensive procedure. The latter served as the gold standard for defining sensitivity and specificity.
Results: For subtests of the short BRB, estimates of sensitivity (38-44 %) and specificity (81-94 %) were obtained. Combining subtests into a single indicator of cognitive deficits yielded increased sensitivity (78 %), while reducing specificity (65 %).
Conclusion: The short BRB is reasonably sensitive and specific in detecting cognitive deficits. However, these qualities only emerge, if the short BRB is administered as a whole, whereas sensitivity is considerably lower than suggested by previous work, when relying on subtests separately (SDMT, PASAT, SRT). While the short BRB may not be regarded as conclusive as an extensive test battery, it represents a valid and economic screening instrument.