Table 2.

Relative frequencies of reliable improvement of the Patient Health Questionnaire-9 (PHQ-9), pre-post change on the PHQ-9 (effect sizes) and adherence by patient group of early change.

Sample		Outcome		Adherence
	n	Reliable improvement on PHQ-9a n (%)	Pre-post ESb on PHQ-9 (d) (95% CI)	Usage time (in hours) mean (SDc)	Number of modules of the Web intervention mean (SD)	Number of assessmentsd mean (SD)
All patients	409	221 (54)	1.12 (0.94-1.30)	7.89 (4.81)	9.10 (4.38)	2.52 (1.25)
Class 1e	158	99 (62)	1.63 (1.39-1.86)	8.36 (4.08)	9.84 (3.90)	2.80 (1.16)
Class 2f	185	104 (56)	1.25 (1.04-1.47)	7.32 (4.69)	8.64 (4.52)	2.37 (1.25)
Class 3g	66	18 (27)	−0.47 (−1.05 to 0.12)	8.33 (6.39)	8.65 (4.85)	2.27 (1.36)
P value		<.001h	<.001i	.10i	.03i	<.001i

^aPHQ-9: Patient Health Questionnaire-9.

^bES: effect size.

^cSD: standard deviation.

^dNumber of assessments: Number of PHQ-9s after week 4.

^eClass 1: Early response after registration.

^fClass 2: Early response after screening.

^gClass 3: Early deterioration.

^hχ² tests were performed, testing the association between class membership and categorized treatment outcome.

ⁱ1-way analysis of variances (ANOVAs) were performed, testing the association between class membership and mean d for pre-post change, usage time, number of modules of the Web intervention, and number of assessments.