Table 3. Comparison of quality-adjusted life years by trial arm, across all participants and stratified by prognostic group (multiple imputed data).

	All participants (n = 1,868)	p-value	Minimal/mild (n = 1,357)	p-value	Moderate (n = 288)	p-value	Severe (n = 223)	p-value
3 months
Mean QALYs (SE) 1
Intervention arm	0.147 (0.0006)		0.164 (0.0008)		0.112 (0.002)		0.089 (0.002)
Control arm	0.145 (0.0006)		0.163 (0.0008)		0.108 (0.001)		0.085 (0.002)
Difference in mean QALYs between arms (95% CI)1	0.002 (-0.0002 to 0.003)	0.09	0.0008 (-0.001 to 0.003)	0.47	0.004 (-0.001 to 0.008)	0.13	0.003 (-0.002 to 0.008)	0.22
Sensitivity analysis2	0.001 (-0.0004 to 0.003)	0.15	0.0007 (-0.001 to 0.003)	0.52	0.003 (-0.001 to 0.008)	0.16	0.003 (-0.002 to 0.008)	0.19
Sensitivity analysis3	0.001 (-0.0009 to 0.003)	0.27	-0.0002 (-0.003 to 0.002)	0.85	0.004 (-0.0008 to 0.009)	0.10	0.004 (-0.001 to 0.010)	0.17
12 months
Mean QALYs (SE) 1
Intervention arm	0.607 (0.004)		0.669 (0.005)		0.482 (0.011)		0.392 (0.012)
Control arm	0.596 (0.004)		0.661 (0.004)		0.465 (0.010)		0.367 (0.011)
Difference in mean QALYs between arms (95% CI)1	0.011 (0.001 to 0.022)	0.049	0.008 (-0.005 to 0.021)	0.23	0.016 (-0.014 to 0.047)	0.29	0.024 (-0.011 to 0.059)	0.18
Sensitivity analysis2	0.010 (-0.001 to 0.021)	0.09	0.00 (-0.006 to 0.020)	0.29	0.016 (-0.015 to 0.046)	0.32	0.024 (-0.010 to 0.059)	0.16
Sensitivity analysis3	0.015 (0.00004 to 0.030)	0.049	0.009 (-0.008 to 0.027)	0.32	0.048 (0.002 to 0.095)	0.04	0.013 (-0.034 to 0.059)	0.59

Abbreviations: QALYs = quality-adjusted life years; SE = standard error; CI = confidence interval

¹ Baseline mean and the difference between the mean for the intervention arm minus the mean for control arm estimated using a generalised linear model (family = Gaussian, link = identity) with random intercepts for individuals and adjusted for baseline AQoL-8D utility weight, baseline PHQ-9 score, general practice and prognostic group (the final covariate only applied to the analysis involving all participants);

² Same as 1, adjusted for factors associated with non-response to the primary outcome measure, the PHQ-9 score, at 3 and 12 months (age, gender, highest level of education, current employment status, hold a health care card, long-term illness, live alone, number of times visited a psychiatrist or counsellor in past 12 months and current use of antidepressants)

³ Same as 1, for complete cases only (i.e., no multiple imputation of missing data)