Do published criteria improve clinical diagnostic accuracy in multiple system atrophy?

Objective: To assess the accuracy of a clinical diagnosis of multiple system atrophy (MSA) and compare it to the Quinn and Consensus criteria for MSA using neuropathologically examined cases from the Queen Square Brain Bank for Neurological Disorders. Methods: Fifty-nine cases with a neurologic diagnosis of MSA when last assessed prior to death were studied. Results: In 51 (86%) of these cases, the diagnosis of MSA was confirmed pathologically. False positive diagnoses included PD (n = 6), progressive supranuclear palsy (n = 1), and cerebrovascular disease (n = 1). When applying either set of diagnostic criteria, a diagnosis of probable MSA gave lower sensitivity but higher positive predictive value than one of possible MSA. Application of either set of diagnostic criteria was superior to actual clinical diagnosis made early in the disease, but there was little difference by the last clinic visit. Conclusions: This study shows a high diagnostic accuracy for the clinical diagnosis of MSA by neurologists, with PD accounting for most of the false positive diagnoses. Application of either Quinn or Consensus criteria was superior to actual clinical diagnosis made early in the disease, but there was little difference by last clinic visit.