Table 3.

Stepwise multiple regression analyses predicting outcome and adherence by patient characteristics, email-support, and patterns of early change.

Steps	Predictorsa	Outcome			Adherence
		PHQ-9b at post			No. of assessmentsc			No. of modules in intervention
		ΔR2	Beta	P	ΔR2	Beta	P	ΔR2	Beta	P
Step 1		0.125		.008	0.036		<.001	0.024		.002
	PHQ-9		.216	<.001		.190	<.001		.155	.002
	HRSD-24d		.199	<.001		−0.043	.41		.051	.33
	APOIe		−0.124	.008		.005	.92		.082	.10
	SupportEmail		−0.004	.96		.066	.45		.002	.98
Step 2		0.215			0.015		.04	0.006		.31
	PHQ-9		−0.040	.50		.192	.007		.146	.04
	HRSD-24		.045	.32		−0.024	.66		.068	.22
	APOI		−0.129	.002		.001	.98		.080	.11
	SupportEmail		−0.068	.36		.073	.41		.003	.97
	C2f-dummy		−0.346	<.001		−0.030	.69		−0.033	.66
	C3f-dummy		.342	<.001		−0.132	.01		−0.082	.13
Total R2		.34			.05			.03
N		409			409			409

^aPredictors included Patient Health Questionnaire-9 (PHQ-9) at screening, 24-item Hamilton Rating Scale for Depression (HRSD-24) at screening, attitudes toward Web-based intervention, email support, and early change patterns.

^bPHQ-9: Patient Health Questionnaire-9.

^cNo. of assessments = No. of PHQ-9 assessments after week 4.

^dHRSD-24: 24-item Hamilton Rating Scare for Depression.

^eAPOI: attitudes toward psychological online interventions.

^fC2 and C3 are dummy coded class membership variables with Class 1: early response after registration, used as reference class.