[Number of nurses and adverse events: the results of a study].

Unlabelled: Number of nurses and adverse events: the results of a study. Introduction. Adverse events may be related to an higher workload and a lower nurse staffing level compared to patients needs.

Objective: To assess the association between adverse events and lower nurse staffing level compared to patients workload, measured with the Nursing Activity Score (NAS).

Method: The daily workload of patients admitted to the Intensive Care Unit of San Gerardo Hospital (Monza) from December 15, 2009 to May 9, 2010 was measured with the NAS. The scores were correlated with the number of nurses on shift over 24 hours, the bed occupancy rate and the adverse events occurred.

Results: Out of a population of 240 patients for a follow-up period of 145 days, 45 adverse events were observed. In the days with events the difference between ideal and actual nurses requirement amounted to -7.68% (±8.84). On days without events, the difference was 0.44% (±7.96) (p value 0.0001). In the days with events patients received less minutes of care than needed -110.66 (±127), and on days without events an excess of minutes of care 6.40 (±115) minutes /patient. The average NAS score of patients with events was 81.88 (±10.00); 73.54 (±13.83) of those without events (p=0.001).

Conclusions: In the period observed adverse events occurred mainly when the difference between patients workload according to NAS and minutes of care provided by nurses on shift was higher.