Internet-based intervention on proper handwashing limits spread of respiratory tract infections [PRIMIT trial]

1. In this open-label, randomized trial, participants that received an internet-based intervention on proper handwashing for respiratory tract infection prevention reported fewer infection and influenza-like episodes after 16 weeks.

2. There were fewer reported total number of days of infection in the intervention group compared to the control group, as well as fewer reported gastrointestinal infections.

Evidence Rating Level: 1 (Excellent)      

Study Rundown: Respiratory tract infections (RTIs) are thought to be spread by close contact between individuals or hand to face contact, and handwashing has been recommended as a method of preventing transmission of infections, especially with the H1N1 influenza pandemic. However, there has not been sufficient evidence in the form of randomized trials to assess the benefit of handwashing. This study attempted to assess whether using the internet as an intervention to modify handwashing would decrease the number of RTIs in adults and their household contacts. All participants were randomly assigned into four groups that received either an internet-based handwashing intervention or no intervention, plus either a baseline questionnaire on handwashing practices or no questionnaire. All participants were followed to 16 weeks with a final questionnaire and reported episodes and duration of infections.

Approximately 20,000 patients were enrolled in the study, with nearly 85% completing the follow-up questionnaire at 16 weeks. There were fewer reported RTI episodes at 16 weeks in the intervention group compared to the control group, with 51% reporting episodes in the intervention group, and 59% in the control group, as well as fewer influenza-like episodes reported in the intervention group. Limitations of the study included that the large sample size required self-reporting of infection episodes, which could have led to reporting bias.

Click to read the study in The Lancet

Relevant Reading: Effect of handwashing on child health: a randomised controlled trial

In-Depth [randomized controlled trial]: This study included adults aged 18 years and older from computerized lists from general practitioner practices in England. 20,066 participants were enrolled from 344 physician offices from England, covering three winter seasons from January 2011 to March 2013. Participants were randomized 1:1 to receive access to an internet-based intervention with an additional questionnaire about handwashing practices or a control group of intervention and no questionnaire. An additional cohort was randomly assigned 1:1 to receive access to an internet intervention but no questionnaire or to a control group of no intervention but received a handwashing questionnaire. The internet intervention consisted of four weekly internet sessions that encouraged participation through new content every week, provided information about influenza and handwashing, and developed a plan to maximize handwashing. The primary outcome was the number of index individuals reporting one or more RTIs at 16 weeks via a final follow-up questionnaire.

16,908 (84%) participants completed the follow-up questionnaire at 16 weeks, including 8,421 in the intervention group and 8,667 in the control group. 4,242 (51%) participants in the intervention group reported one or more RTI episodes at 16 weeks versus 5,135 (59%) in the control group (multivariate risk ratio 0.86, 95% Confidence Interval [CI] 0.83-0.89; p<0.0001). Additionally, the intervention group had fewer total number of days of infections compared to the control group (5.2 days [SD 8.4] vs. 6.5 days [9.0]; multivariate incident rate ratio 0.91, 95% CI 0.87-0.95; p<0.0001). There were also fewer gastrointestinal infections reported in the intervention group than the control group.

Image: PD

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