Reliability of Three Disability Scales for Detection of Independence Loss in Parkinson’s Disease

Table 2

Reliability of the Hoehn and Yahr stage, Schwab and England scale, and Barthel ADL index in the detection of loss of independence in PD compared to clinical interview.

	Sensitivity	Specificity	PPV	NPV	AUC	Kappa
Hoehn and Yahr
Stage > 3.0	21%	98%	86%	68%	0.59	0.22
Stage > 2.0	67%	72%	58%	79%	0.70	0.38
Schwab and England
Score < 80%	55%	92%	80%	78%	0.74	0.50
Score < 90%	85%	69%	61%	88%	0.77	0.50
Barthel ADL index
Score < 20	67%	78%	64%	80%	0.73	0.45

Optimal cut-off according to Youden’s J-statistic and ROC curve analysis.
Kappa values exceeding 0.20 represent fair, 0.40 moderate, and 0.60 substantial strength of agreement between tests.
AUC: area under curve from ROC curve analyses; PPV: positive predictive value; NPV: negative predictive value.