Patient to nurse ratio and risk of ventilator-associated pneumonia in critically ill patients.

OBJECTIVE To determine how the patient to nurse ratio affects risk for ventilator-associated pneumonia. METHODS Data from an earlier study in 27 intensive care units in 9 European countries were examined in a secondary analysis. The initial cohort included 2585 consecutive patients who had mechanical ventilation (1) after admission for treatment of pneumonia or (2) for more than 48 hours irrespective of the diagnosis at admission. In units with variable staffing levels, the highest patient to nurse ratio in a 24-hour period was considered. Patients from 6 units that did not provide data on nurse staffing levels were excluded from the analysis. RESULTS Ventilator-associated pneumonia developed in 393 of the 1658 patients (23.7%) in the secondary cohort. In units with patient to nurse ratios of 1 to 1, 2 to 1, 2.5 to 1, and 3 to 1, rates were 9.3%, 25.7%, 18.7%, and 24.2%, respectively (P = .003). Rates were significantly lower (P = .002) in units with a ratio of 1 to 1 (9.3%) than in units with a ratio of more than 1 patient to 1 nurse (24.4%). After adjustments for confounding covariates, ratios of more than 1 patient to 1 nurse were no longer associated with increased risk for ventilator-associated pneumonia. CONCLUSIONS A patient to nurse ratio of 1 to 1 appears to be associated with a lower risk for ventilator-associated pneumonia, but after adjustments for confounding covariates, the difference is not significant.