Explaining the effects of two different strategies for promoting hand hygiene in hospital nurses: a process evaluation alongside a cluster randomised controlled trial.

Background: There is only limited understanding of why hand hygiene improvement strategies are successful or fail. It is therefore important to look inside the 'black box' of such strategies, to ascertain which components of a strategy work well or less well. This study examined which components of two hand hygiene improvement strategies were associated with increased nurses' hand hygiene compliance.

Methods: A process evaluation of a cluster randomised controlled trial was conducted in which part of the nursing wards of three hospitals in the Netherlands received a state-of-the-art strategy, including education, reminders, feedback, and optimising materials and facilities; another part received a team and leaders-directed strategy that included all elements of the state-of-the-art strategy, supplemented with activities aimed at the social and enhancing leadership. This process evaluation used four sets of measures: effects on nurses' hand hygiene compliance, adherence to the improvement strategies, contextual factors, and nurses' experiences with strategy components. Analyses of variance and multiple regression analyses were used to explore changes in nurses' hand hygiene compliance and thereby better understand trial effects.

Results: Both strategies were performed with good adherence to protocol. Two contextual factors were associated with changes in hand hygiene compliance: a hospital effect in long term (p < 0.05), and high hand hygiene baseline scores were associated with smaller effects (p < 0.01). In short term, changes in nurses' hand hygiene compliance were positively correlated with experienced feedback about their hand hygiene performance (p < 0.05). In the long run, several items of the components 'social influence' (i.e., addressing each other on undesirable hand hygiene behaviour p < 0.01), and 'leadership' (i.e., ward manager holds team members accountable for hand hygiene performance p < 0.01) correlated positively with changes in nurses' hand hygiene compliance.

Conclusion: This study illustrates the use of a process evaluation to uncover mechanisms underlying change in hand hygiene improvement strategies. Our study results demonstrate the added value of specific aspects of social influence and leadership in hand hygiene improvement strategies, thus offering an interpretation of the trial effects.

Trial Registration: The study is registered in ClinicalTrials.gov, dossier number: NCT00548015.