Table 2.

Accuracy of the 3-item UCLA Loneliness Scale in classifying mental health problems.

	Threshold	Age-18 Sample					Age-38 Sample
		Sensitivity	Specificity	PPV	Youden’s J	Distance from Top-Left	Sensitivity	Specificity	PPV	Youden’s J	Distance from Top-Left
	3	1.00	0.00	0.20	0.00	1.00	1.00	0.00	0.16	0.00	1.00
Depression	4	0.75	0.54	0.29	0.28	0.28	0.74	0.55	0.24	0.29	0.27
	5	0.59	0.73	0.36	0.33	0.24	0.57	0.75	0.31	0.32	0.25
	6	0.42	0.86	0.44	0.29	0.35	0.44	0.87	0.39	0.31	0.33
	7	0.22	0.95	0.53	0.17	0.62	0.29	0.96	0.61	0.25	0.50
	8	0.12	0.98	0.64	0.11	0.77	0.14	0.99	0.73	0.13	0.74
	9	0.05	1.00	0.75	0.05	0.90	0.05	0.99	0.62	0.05	0.90
	AUC	0.70 (0.67–0.73)					0.71 (0.67–0.76)
Anxiety	3	1.00	0.00	0.07	0.00	1.00	1.00	0.00	0.06	0.00	1.00
	4	0.84	0.50	0.12	0.34	0.27	0.81	0.52	0.09	0.34	0.26
	5	0.74	0.70	0.16	0.44	0.16	0.72	0.72	0.13	0.44	0.16
	6	0.55	0.84	0.21	0.39	0.23	0.54	0.84	0.17	0.38	0.24
	7	0.31	0.94	0.28	0.25	0.48	0.24	0.93	0.18	0.17	0.58
	8	0.21	0.98	0.40	0.18	0.63	0.19	0.98	0.33	0.16	0.66
	9	0.09	0.99	0.50	0.09	0.82	0.06	0.99	0.23	0.04	0.89
	AUC	0.76 (0.72–0.80)					0.75 (0.68–0.82)
Self-harm/suicide attempt	3	1.00	0.00	0.14	0.00	1.00	1.00	0.00	0.15	0.00	1.00
	4	0.81	0.53	0.22	0.33	0.26	0.65	0.53	0.19	0.19	0.34
	5	0.66	0.72	0.28	0.38	0.19	0.52	0.73	0.25	0.25	0.30
	6	0.43	0.85	0.32	0.28	0.34	0.34	0.84	0.27	0.18	0.46
	7	0.21	0.94	0.36	0.15	0.63	0.22	0.95	0.41	0.16	0.62
	8	0.12	0.98	0.44	0.09	0.78	0.09	0.98	0.40	0.06	0.84
	9	0.05	0.99	0.52	0.04	0.91	0.05	0.99	0.54	0.04	0.90
	AUC	0.72 (0.69–0.76)					0.64 (0.59–0.69)

AUC = Area under the curve. PPV = Positive predictive value. Numbers in brackets reflect 95% confidence intervals.