The effectiveness and cost-effectiveness of lay counsellor-delivered psychological treatments for harmful and dependent drinking and moderate to severe depression in primary care in India: PREMIUM study protocol for randomized controlled trials

Table 2 Power calculations for the Healthy Activity Program trial

Outcome	Total sample size	Number per arm	Number of clinics	Treatment arm	Enhanced usual care arm	SD	Effect size	Power
BDI-II mean score (primary)	500	250	8	16.8	17.9^a	2.8^a	0.4^c	86%
	500	250	8	16.65	17.9^a	2.8^a	0.45^c	93%
	500	250	8	16.5	17.9^a	2.8^a	0.5^c	97%
	500	250	8	18.9	24.5^b	10.7^b	0.5	98%
Remission (PHQ-9 < 10) (primary)	500	250	8	62%	44%^d	-	-	81%
	500	250	8	65%	44%^d	-	-	92%
WHO DAS mean score (secondary)	500	250	8	15.0	17.0^e	5.0^e	0.4	87%
	500	250	8	14.5	17.0^e	5.0^e	0.5	97%

^aBased on pilot PREMIUM data, where BDI score was 17.9 with SD 2.8. ^bBased on the COBALT trial [5]. The mean BDI-II score at six months was 24.5 (SD 13.1) in the usual care arm and 18.9 (SD 14.2) in the intervention arm (among participants with a BDI > 14 at baseline). The study reported an effect size of 0.53, based on the pooled SD of baseline BDI-II score (SD = 10.7). ^cEffect size of 0.4 to 0.5 is based on the recent meta-analyses of behavioural therapy for depression, which found a summary effect size of 0.42 for depressive symptoms based on low intensity interventions (internet-based or guided interventions with limited support by a health professional) [38] and of 0.7 (95% CI: 0.39, 1.00) for all behavioural interventions [39]. Two further trials found effect sizes of 0.53 [5] for a cognitive behavioural therapy-intervention on BDI score and 0.76 [40] for behavioural activation on BDI score. ^dProportion recovered from any common mental disorder among baseline depression cases in MANAS in the enhanced usual care arm at three months. ^eBased on 12-month WHO-DAS scores among those who had moderate or severe common mental disorders at baseline in the MANAS trial. BDI, Beck’s Depression Inventory; PHQ-9, Patient Health Questionnaire-9; WHO DAS, World Health Organization Disability Assessment Schedule.

ISSN: 1745-6215