Technical note: Assessment of blinding of hand hygiene observers in randomized controlled trials of hand hygiene interventions.

Trials evaluating interventions to improve health care workers' hand hygiene compliance use directly observed compliance as a primary outcome measure. Observers should be blinded to the intervention and the effectiveness of blinding assessed to prevent systematic bias. The literature has not addressed this issue, and this study describes a robust and pragmatic method for assessing the adequacy of blinding in hand hygiene intervention trials.