Past research suggests a relationship between nursing workload and quality of care in hospitalized patients. This study examined the relationship between hospital workload and adverse events and discovered that a hospital operating consistently near capacity had increased rates of adverse events. Investigators reviewed more than 6800 patient charts at four different teaching hospitals and found workload effects at only one of the sites. At this site, they estimated that a 10% increase in occupancy led to a 15% increase in adverse events. The authors suggest that consistently high workloads, where patient to nurse ratios may increase, pose a risk to patient safety.