Effect Evaluation of a Randomized Trial to Reduce Infectious Illness and Illness-Related Absenteeism Among Schoolchildren: The Hi Five Study

Background: Previous school-based hand hygiene interventions have reported to successfully reduce infectious illness among schoolchildren. But few studies have tested the effect in large populations with adequate statistical power and analyses. The aim of this study was to evaluate whether a school-based multicomponent intervention to improve handwashing among schoolchildren, the Hi Five study, succeeded in reducing infectious illness and illness-related absenteeism in schools. Methods: The Hi Five study was a three-armed cluster-randomized controlled trial involving 43 randomly selected Danish schools; two intervention arms involving 14 schools each, and 15 control schools. Infectious illness days, infectious illness episodes and illness-related absenteeism were estimated in multilevel regressions, based on available cases of text messages answered by parents and based on questionnaire data reported by schoolchildren, respectively. Results: At follow-up, children in the intervention schools did not differ from the control schools in number of illness days [odds ratio (OR) _{I-arm I}: 0.91 (0.77-1.07) and OR _{I-arm II}: 0.94 (0.79-1.12)] and illness episodes [OR _{I-arm I}: 0.95 (0.81-1.11) and OR _{I-arm II}: 0.98 (0.84-1.16)] or in reporting illness-related absenteeism [OR _{I-arm I}: 1.09 (0.83-1.43) & OR _{I-arm II}: 1.06 (0.81-1.40)]. Conclusions: The multicomponent Hi Five intervention achieved no difference in the number of illness days, illness episodes or illness-related absenteeism among children in intervention schools compared with control schools. It is noteworthy that one of the main components in the intervention, a mandatory daily handwashing before lunch, was only implemented by 1 of 3 of teachers in intervention schools.