An application of factorial design to compare the relative effectiveness of hospital infection control measures

Optimal methods to control patient-to-patient transmission of methicillin-resistant Staphylococcus aureus (MRSA) in an intensive care unit (ICU) setting are still unknown. We iteratively applied a full 2^k factorial design on the output of a stochastic, agent-based simulation to compare the effects of the hand hygiene compliance of healthcare workers and the nurse-to-patient ratio on the transmission of MRSA in a 20-bed ICU. The results suggest that increasing the nurse-to-patient ratio is more effective at levels below approximately 60% compliance of nurses. However, improving the hand washing compliance of nurses becomes the better strategy at higher baseline compliance levels. In addition, interaction effects between the two infection control measures limit the marginal benefit of improving both factors to high levels.