Table 4 Power calculations: SHARE trials

Unit of randomisation

Villages (stratified within union councils)

Individual (stratified by urban/rural area of residence)

Intra-cluster correlation

0.07 in the intervention arm

0.05 in the intervention arm (30 therapists; within-therapist clustering) [22, 32, 33]

0.05 in the control arm (between-village clustering) [22]

Loss to follow-up over 6 months

20 % [22]

15 % [8]

Allocation ratio (intervention/control)

1:1

1:1

Number of participants

560 (14 per village; 40 village clusters)

280

Outcome

Remission at 6 months (PHQ-9 < 10) of 65 % in the intervention arm vs 45 % in the control arm [22]

90 %

86 %

Remission at 6 months (PHQ-9 ≤ 5) of 38 % in the intervention arm vs 22 % in the control arm [22]

81 %

74 %

Depression severity at 6 months (PHQ-9 score) – effect size 0.4

90 %

84 %