Cluster-randomised trial to test the effect of a behaviour change intervention on toilet use in rural India: results and methodological considerations.

backgroundEffective and scalable behaviour change interventions to increase use of existing toilets in low income settings are under debate. We tested the effect of a novel intervention, the '5 Star Toilet' campaign, on toilet use among households owning a toilet in a rural setting in the Indian state of Gujarat.

methodsThe intervention included innovative and digitally enabled campaign components delivered over 2 days, promoting the upgrading of existing toilets to achieve use by all household members. The intervention was tested in a cluster randomised trial in 94 villages (47 intervention and 47 control). The primary outcome was the proportion of households with use of toilets by all household members, measured through self- or proxy-reported toilet use. We applied a separate questionnaire tool that masked open defecation questions as a physical activity study, and excluded households surveyed at baseline from the post-intervention survey. We calculated prevalence differences using linear regression with generalised estimating equations.

resultsThe primary study outcome was assessed in 2483 households (1275 intervention and 1208 control). Exposure to the intervention was low. Post-intervention, toilet use was 83.8% in the control and 90.0% in the intervention arm (unadjusted difference + 6.3%, 95%CI 1.1, 11.4, adjusted difference + 5.0%, 95%CI -0.1, 10.1. The physical activity questionnaire was done in 4736 individuals (2483 intervention and 2253 control), and found no evidence for an effect (toilet use 80.7% vs 82.2%, difference + 1.7%, 95%CI -3.2, 6.7). In the intervention arm, toilet use measured with the main questionnaire was higher in those exposed to the campaign compared to the unexposed (+ 7.0%, 95%CI 2.2%, 11.7%), while there was no difference when measured with the physical activity questionnaire (+ 0.9%, 95%CI -3.7%, 5.5%). Process evaluation suggested that insufficient campaign intensity may have contributed to the low impact of the intervention.

conclusionThe study highlights the challenge in achieving high intervention intensity in settings where the proportion of the total population that are potential beneficiaries is small. Responder bias may be minimised by masking open defecation questions as a physical activity study. Over-reporting of toilet use may be further reduced by avoiding repeated surveys in the same households.

trial registrationThe trial was registered on the RIDIE registry ( RIDIE-STUDY-ID-5b8568ac80c30 , 27-8-2018) and retrospectively on clinicaltrials.gov ( NCT04526171 , 30-8-2020).