Table 1

Diagnostic and predictive value of various clinical features compared with postmortem diagnosis of multiple system atrophy and Parkinson's disease

Variables		MSA	PD	X²value on 1 df	Sensitivity (%)	Specificity (%)	PPV	NPV	Youden index
Sociodemographic:
Sex	(M)	20	64	0.22	52.6	36.0	23.8	66.7	−11.4
	(F)	18	36
Age onset⩽55 y	(Y)	16	20	0.008	42.1	80.0	44.4	78.4	22.1
	(N)	22	80
Initial features:
Symmetric onset	(Y)	9	28	0.99	28.1	71.7	24.3	75.5	−0.2
	(N)	23	71
Initial HY>2	(Y)	13	21	0.002	54.2	78.1	38.2	87.2	32.3
	(N)	11	75
Initial rigidity	(Y)	21	30	0.005	56.8	69.7	41.2	81.2	26.5
	(N)	16	69
Initial poor levodopa response	(Y)	18	22	0.0001	58.1	76.8	45.0	84.9	34.9
	(N)	13	73
Clinical features^2-150:
Tremor	(Y)	23	76	0.07	60.5	24.0	23.2	61.5	−15.5
	(N)	15	24
Rigidity	(Y)	37	96	0.7	97.4	4.0	27.8	80.0	1.4
	(N)	1	4
Bradykinesia	(Y)	36	90	0.16	97.3	10.0	28.6	90.9	7.3
	(N)	1	10
Autonomic	(Y)	32	26	0.0001	84.2	73.7	55.2	92.4	57.9
	(N)	6	73
Cerebellar	(Y)	12	1	0.0001	32.4	99.0	92.3	79.7	31.4
	(N)	25	98
Pyramidal	(Y)	18	7	0.0001	50.0	92.9	72.0	83.6	42.9
	(N)	18	92
Speech and/or bulbar	(Y)	33	21	0.0001	86.8	78.8	61.1	94.0	65.6
	(N)	5	78
Dementia absent	(Y)	29	44	0.0001	82.9	54.6	39.7	89.8	37.5
	(N)	6	53
Early dementia absent	(Y)	29	78	0.01	100.0	17.9	27.1	100.0	17.9
	(N)	0	17
Asymmetric disease	(Y)	13	54	0.033	34.2	45.5	19.4	64.3	−20.3
	(N)	25	45
Drug side effects:
Toxic confusion absent	(Y)	27	27	0.0001	84.4	71.9	50.0	93.2	56.3
	(N)	5	69
Early toxic confusion absent	(Y)	27	80	0.04	100.0	14.0	25.2	100.0	14.0
	(N)	0	13
Fluctuations	(Y)	15	58	0.18	46.9	39.6	20.5	69.1	−13.5
	(N)	17	38
Early fluctuations	(Y)	14	19	0.006	45.2	80.0	42.4	81.7	25.2
	(N)	17	76
Dyskinesia	(Y)	15	59	0.14	45.5	39.8	20.3	68.4	−14.7
	(N)	18	39
Early dyskinesias	(Y)	8	18	0.43	25.0	81.4	30.8	76.7	6.4
	(N)	24	79
Other features:
Other signs	(Y)	30	12	0.0001	78.9	88.0	71.4	91.7	66.9
	(N)	8	88
Other causes	(Y)	3	20	0.09	7.9	80.0	13.0	69.6	−12.1
	(N)	35	80
Depression	(Y)	14	56	0.24	51.9	35.6	20.0	70.5	−12.5
	(N)	13	31
Falls	(Y)	31	54	0.001	86.1	44.3	36.5	89.6	30.4
	(N)	5	43
Family history	(Y)	2	4	0.65	5.9	96.0	33.3	75.0	1.9
	(N)	32	96

PPV=positive predictive value; NPV=negative predictive value.
↵2-150 Recorded at any time up to death.
Youden index = sensitivity plus specificity minus 100. Values can vary from between 100 to−100, a larger value indicating a more useful feature.