Table 1.

Predictive power of the number of MA-positive thrice weekly urine drug screens during first two weeks of treatment for persistent MA use at end-of-treatment (EOT) among placebo group participants^*

MA Positive Screens	Sensitivity	Specificity	PPV	NPV	LR+	LR−
=6	35.2	98.2	98	39	19.69	0.66
>=5	50.8	94.6	96	46	9.48	0.52
>=4	57.0	85.7	90	47	3.99	0.50
>=3	66.4	80.4	89	51	3.38	0.42
>=2	75.0	71.4	86	56	2.63	0.35
>=1	83.6	57.1	82	60	1.95	0.29

^*ROC analysis assessed number of MA positive/missing urine drug screens to predict MA use at EOT. Bolded is optimal Youden (1950) predictor; PPV=positive predictive value; NPV=negative predictive value; LR+ = positive likelihood ratio; LR− = negative likelihood ratio