Understaffing, overcrowding, inappropriate nurse:ventilated patient ratio and nosocomial infections: which parameter is the best reflection of deficits?

Background: In stressed and high-throughput systems, periodic overcrowding (high bed occupancy) and understaffing (low nurse: patient ratio) are widely described risk factors for nosocomial infections. Aim: The impact of bed occupancy (patient: bed ratio), nurse: patient ratio and nurse: ventilated patient ratio on nosocomial bloodstream infections (BSI) and pneumonia were investigated in 182 intensive care units (ICU). Methods: The ICUs reported monthly data on device use and nosocomial device-associated infections to the German hospital surveillance system for nosocomial infections in 2007. Information on the number of healthcare workers on the ward per 24 h in 2007 and structure parameters was obtained by questionnaires. The association between occupancy or staff parameters and the number of nosocomial infections per month was analysed using generalized estimating equation models. Findings: In total, 1313 cases of pneumonia and 513 cases of BSI were reported from 182 ICUs with 1921 surveillance months and 563,177 patient-days. Fewer nosocomial infections were associated with a higher nurse: ventilated patient ratio [adjusted incidence rate ratio 0.42 (95% confidence interval 0.32-0.55) for months with nurse: ventilated patient ratios >75th percentile compared with <= 25th percentile]. Interestingly, the nurse: patient ratio was not a significant parameter with respect to the occurrence of BSI and pneumonia. High bed occupancy (>75th percentile) was associated with fewer nosocomial infections. Conclusion: A staffing parameter that reflects the intensity of care, such as the nurse: ventilated patient ratio, may enable better evaluation of workload and resources, especially at a time when nursing resources are being reduced but nosocomial infections are increasing. (C) 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.