Are Clinical Certainty Ratings Helpful in the Diagnosis of Parkinson's Disease?

Background: Clinical diagnostic criteria for PD rely on rest tremor, bradykinesia, and rigidity. These features are non-specific and neuropathological confirmation remains the gold standard for diagnosis. This study presents data on clinical certainty ratings in autopsy-proven PD.

Methods: Subjects were assessed annually by a movement disorders specialist and assigned to a clinical certainty group for PD based on multiple clinical features before autopsy. The three groups considered for analysis are as follows: Group I 0-49% certainty, Group II 50-89% certainty, and Group III 90-100% certainty. All subjects were autopsied and had a standardized neuropathological assessment.

Results: 275 subjects were assigned a PD certainty at their last visit before death. Group I had 80 subjects, Group II 56 subjects, and Group III 139 subjects. The clinical features recorded in Group I, II, and III, were as follows: rest tremor, bradykinesia, rigidity, postural instability, asymmetric onset, persistent asymmetry, current response to dopaminergic treatment, motor fluctuations, and dyskinesia. Rigidity, postural instability, asymmetric onset, current response to dopaminergic treatment, motor fluctuation, and dyskinesia were more likely to be present in the group which was rated with higher certainty. The final diagnosis of PD was confirmed by neuropathological assessment in 85% of the patients in Group III as compared to 30% in Group II and 5% in Group I.

Conclusions: High certainty (90-100%) had strong positive predictive value (85%) for autopsy-proven PD as compared to either lower certainty groups (0-49% and 50-89%) which had lower predictive value (5% and 30% respectively).