Table 3.

ROC Analysis to Determine Optimal Cut-Point for CTR^a

	Total Accuracy		Sensitivity		Specificity		PPV		NPV
CTR	Any	Severe	Any	Severe	Any	Severe	Any	Severe	Any	Severe
0.1	0.77	0.87	0.03	0.03	0.99	0.99	0.38	0.25	0.78	0.88
0.2	0.76	0.85	0.09	0.09	0.95	0.95	0.34	0.21	0.79	0.88
0.3	0.74	0.82	0.15	0.17	0.91	0.91	0.33	0.20	0.79	0.89
0.4	0.71	0.77	0.26	0.28	0.83	0.83	0.31	0.19	0.80	0.89
0.5	0.63	0.66	0.41	0.44	0.69	0.69	0.27	0.16	0.80	0.90
0.6	0.60	0.62	0.50	0.53	0.63	0.63	0.28	0.16	0.82	0.91
0.7	0.56	0.56	0.60	0.63	0.55	0.55	0.28	0.16	0.83	0.92
0.8	0.52	0.50	0.70	0.73	0.47	0.47	0.27	0.16	0.85	0.93
0.9	0.48	0.45	0.78	0.80	0.40	0.40	0.27	0.15	0.86	0.93

^aCTR: zero excluded.

CTR = COPD treatment ratio; NPV = negative predictive value; PPV = positive predictive value; ROC = receiver operating characteristics.