Table 3.

Sensitivity, specificity, and positive predictive value (PPV) for tests used in the screening for Parkinson's disease (PD) and for Alzheimer's disease (AD) or mild cognitive impairment (MCI)^a

Step 1 tests versus Step 2 tests				Step 2 tests versus Step 3 diagnoses
	Sensitivity	Specificity	PPV		Sensitivity	Specificity	PPV
	Step 2 motor failure (UPDRS)				Step 3 PD diagnosis
Step 1 overall motor failure criteria (n=388)b	93.1	22.5	37.7	Step 2 motor failure (UPDRS) (n=367)d	100	75.8	28.3
Symptoms, any of 2 positive (n=385)	62.0	71.1	51.9
Tremor (n=386)	40.3	90.3	67.5
Balance (n=387)	46.9	75.5	49.2
Spiral drawing failure (n=382)	90.5	28.5	38.4
	Step 2 cognitive failure (MMSE)				Step 3 MCI or AD diagnosis
Step 1 overall cognitive failure criteria (n=380)c	92.8	29.0	26.7	Step 2 cognitive failure (MMSE) (n=367)e	96.4	93.6	72.6
Animal fluency <10 (n=388)	51.2	82.6	52.3
Word recall <3 (n=378)	88.0	32.5	26.8

^aThe denominators in Step 2 include 24 subjects with negative motor and cognitive test results in Step 1, assumed to be disease-free and untested in Step 2; the denominators in Step 3 include 199 subjects with negative motor and cognitive test results in Step 2, assumed to be disease-free and untested in Step 3.

^bOverall motor failure criteria, Step 1: any of the two-symptom questions positive OR ≥ 4 abnormal spiral drawings on either hand.

^cOverall cognitive failure criteria, Step 1: animal fluency <10 OR word recall<3.

^dStep 2 motor failure: abnormal tremor-at-rest OR abnormal postural tremor OR ≥ 2 other abnormal UPDRS items.

^eStep 2 cognitive failure: MMSE score<24.