Risk-adjusted surveillance of hospital-acquired infections in neonatal intensive care units: a systematic review

Comparisons of bacteraemia incidence between neonatal intensive care units (NICUs) can identify centres with effective infection control, whose practices can be shared with other units. For fair comparisons, infection incidence must be risk-adjusted to control for differences between centres in the vulnerability of babies and the intensity of invasive procedures which can introduce infection. We reviewed risk adjustment methods for between-NICU comparisons of bacteraemia incidence, both in the published literature and in regional and national NICU infection monitoring systems. PubMed and Embase were searched for studies reporting risk-adjusted bacteraemia incidence in more than one NICU. An internet search found NICU infection monitoring systems in Western industrialised countries. In all nine studies that met the inclusion criteria, risk adjustment reduced but did not eliminate variation in bacteraemia incidence between NICUs. In both the studies and the regional monitoring systems, adjustment for baby susceptibility generally involved stratification by factors measured at birth. Adjustment for Length of stay and invasive procedures involved reporting incidence by days with a device, such as central venous catheter days. Methods for NICU infection monitoring lack consistency. Adjustment for factors measured at birth fails to capture changes in susceptibility throughout admission and adjustment for device days does not adequately reflect risk to babies not treated with the device. Further research should address variation in risk for all babies throughout their NICU stay.