Table 6.

Performance of the prediction models of depression screening status for different cutoff points and varying sets of selected digital biomarkers.

Outcome cutoff point and model (feature set)		No information rate	Accuracy	Sensitivity	Specificity	PPVa	NPVb	κ	AUCc
PHQ-9d score of ≥10 at assessment 1 or 2 (n=38 in depressed group)
	A1e	0.86	0.86	0.05	0.99	0.50	0.86	0.07	0.66
	B1f	0.86	0.86	0.03	1.00	0.50	0.86	0.04	0.63
	C1g	0.86	0.86	0.03	1.00	1.00	0.86	0.04	0.51
	A2h	0.86	0.86	0.03	1.00	0.50	0.86	0.04	0.64
	B2h	0.86	0.86	0.13	0.98	0.56	0.87	0.17	0.64
	C2h	0.86	0.86	0.05	1.00	0.67	0.86	0.08	0.61
PHQ-9 score of ≥8 at assessment 1 or 2 (n=22 in depressed group)
	A1	0.92	0.92	0.05	1.00	1.00	0.92	0.08	0.64
	B1	0.92	0.92	0.00	1.00	N/Ai	0.92	0.00	0.54
	C1	0.92	0.92	0.05	1.00	1.00	0.92	0.08	0.56
	A2	0.92	0.92	0.05	1.00	1.00	0.92	0.08	0.67
	B2	0.92	0.92	0.00	1.00	N/A	0.92	0.00	0.58
	C2	0.92	0.92	0.05	1.00	1.00	0.92	0.08	0.62
PHQ-9 average score of ≥8 (n=42 in depressed group)
	A1	0.84	0.85	0.12	0.99	0.63	0.86	0.16	0.70
	B1	0.84	0.85	0.19	0.97	0.57	0.87	0.23	0.67
	C1	0.84	0.85	0.02	1.00	1.00	0.85	0.04	0.62
	A2	0.84	0.87	0.24	0.99	0.77	0.87	0.31	0.74
	B2	0.84	0.85	0.17	0.98	0.64	0.86	0.21	0.70
	C2	0.84	0.85	0.07	1.00	1.00	0.85	0.12	0.62

^aPPV: positive predictive value.

^bNPV: negative predictive value.

^cAUC: area under the curve.

^dPHQ-9: 9-item Patient Health Questionnaire.

^eModel A1 includes digital biomarkers selected at a significance level of <.01.

^fModel B1 includes digital biomarkers selected at a significance level of <.05.

^gModel C1 includes digital biomarkers selected at a significance level of <.05 and ≥.01.

^hModels A2, B2, and C2 additionally include sociodemographic characteristics: age, gender, ethnic group, and marital status.

ⁱN/A: not applicable, due to division by zero.