A novel experience in the use of control charts for the detection of nosocomial infection outbreaks

OBJECTIVE: This study aims to compare different control charts to monitor the nosocomial infection rate per 1,000 patient-days. METHODS: The control charts considered in this study were the traditional Shewhart chart and a variation of this, the Cumulative Sum and Exponentially Weighted Moving Average charts. RESULTS: We evaluated 238 nosocomial infections that were registered in the intensive care unit and were detected by the Committee for Nosocomial Infection Control in a university hospital in Belo Horizonte, Brazil, in 2004 and 2005. The results showed that the traditional Shewhart chart was the most appropriate method for monitoring periods with large deviations, while the Exponentially Weighted Moving Average and Cumulative Sum charts were better for monitoring periods with smaller deviations of the mean infection rate. CONCLUSION: The ability to detect nosocomial outbreaks was improved by using the information provided by all three different control charts.