A Cochrane review included 22 RCTs: 12 trials from child day-care centres or schools in mainly high-income countries (54,006 participants), nine community-based trials in low- and middle-income countries (LMICs) (15,303 participants), and one hospital-based trial among people with acquired immune deficiency syndrome (AIDS) (148 participants).
Hand washing promotion (education activities, sometimes with provision of soap) at child day-care facilities or schools prevents around one-third of diarrhoea episodes in high income countries (RR 0.70; 95% CI 0.58 to 0.85; nine trials, 4664 participants), and may prevent a similar proportion in LMICs but only two trials from urban Egypt and Kenya have evaluated this (RR 0.66, 95% CI 0.43 to 0.99; two trials, 45,380 participants). Only three trials reported measures of behaviour change and the methods of data collection were susceptible to bias. In one trial from the USA hand washing behaviour was reported to improve; and in the trial from Kenya that provided free soap, hand washing did not increase, but soap use did (data not pooled; three trials, 1845 participants).
Hand washing promotion among communities in LMICs probably prevents around one-quarter of diarrhoea episodes (RR 0.72, 95% CI 0.62 to 0.83; eight trials, 14,726 participants). In six trials, soap was provided free alongside hand washing education, and the overall average effect size was larger than in the two trials which did not provide soap (soap provided: rate ratio 0.66, 95% CI 0.56 to 0.78; six trials, 11,422 participants; education only: rate ratio: 0.84, 95% CI 0.67 to 1.05; two trials, 3304 participants). There was increased hand washing at major prompts (before eating/cooking, after visiting the toilet or cleaning the baby's bottom), and increased compliance to hand hygiene procedure (behavioural outcome) in the intervention groups than the control in community trials (data not pooled: three trials, 3490 participants). Hand washing promotion for the one trial conducted in a hospital among high-risk population showed significant reduction in mean episodes of diarrhoea (1.68 fewer) in the intervention group (MD 1.68, 95% CI 1.93 to 1.43; one trial, 148 participants). There was increase in hand washing frequency, seven times per day in the intervention group versus three times in the control in this hospital trial (one trial, 148 participants). No trials were found evaluating or reporting the effects of hand washing promotions on diarrhoea-related deaths, all-cause-under five mortality, or costs.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and inadequate follow up).