Promoting effective handwashing: a cluster-randomized controlled trial testing the effectiveness of theory-based interventions

  • M. Friedrich
  • H. Mosler


Consistent hand hygiene prevents diarrheal and respiratory diseases, but it is often not practiced in every-day life. The disease burden is highest in low-income settings. We tested if theory-based interventions using the risks attitudes, norms, abilities and self-regulation (RANAS) model can effectively promote domestic handwashing. In this randomized, controlled trial (N=270), communities were randomized to a theory-based intervention or a control condition. Outcome measures were surveyed at baseline and six weeks’ follow-up and included observed handwashing frequency, technique and faecal hand contamination before and after handwashing. In addition, mediation analyses were performed to reveal the changes in psychosocial factors underlying behaviour change. The intervention resulted in handwashing with soap at 28% of critical handwashing times, while the corresponding figure for the non-intervention control was 5% (p=.004). Changes in handwashing frequency were mediated by changes in descriptive norms, action knowledge and remembering. Handwashing technique, measured as the number of correctly performed handwashing steps, increased to an average of 6.2, while the control averaged 5.2 steps (p<.001). Improvement in handwashing technique was mediated through changes in descriptive norms and action knowledge. No statistically significant group differences in faecal hand contamination were detected. The results provide strong evidence that the intervention successfully improved both handwashing frequency and technique. It shows that theory-driven interventions, provide effective means to trigger substantial health behaviour change in every-day life. The fact that the microbial effectiveness of handwashing did not improve despite strong improvements in handwashing technique calls for critical evaluation of existing handwashing recommendations.