As nursing staff numbers increase, death and infection rates drop and the quality of care rises. That's the consensus of three recent studies.

Canadian researchers examined the impact of 19 nursing care variables on the 30-day mortality rate in acute-care patients. They found that hospitals with higher proportions of RNs and nurses with bachelor's degrees have lower patient death rates. In addition, the study revealed that routine use of care maps or protocols to guide patient care lowers death rates.

Tourangeau and colleagues followed nearly 47,000 patients admitted to 75 teaching or community hospitals for heart attack, stroke, pneumonia, or septicemia. The 30-day mortality rate averaged 17%, ranging from 10% to 28%; eight of the 19 nursing variables accounted for 45% of the variation in the rate. Increasing the proportion of RNs on staff by 10% resulted in six fewer deaths per 1,000 discharged patients, and similarly increasing the proportion of nurses with bachelor's degrees lowered the death rate by nine per 1,000 discharged patients. Hospitals where nurses reported adequate staffing and resources also had lower death rates. Care maps, which were regularly used in an average of 63% of the hospitals (ranging from 29% to 85%), improved patient survival.

The authors suggest that hospitals should "carefully plan and manage structures and processes of care such as the proportion of registered nurses in the staff mix, percentage of baccalaureate-prepared nurses, and routine use of care maps to minimize unnecessary patient death."

A separate study from Geneva found that as the ratio of nurses to patients rises, the risk of infection falls. The researchers, who tracked 1,883 patients admitted to an ICU during a four-year period, determined that approximately 27% of the hospital-acquired infections could have been avoided if the nurse-to-patient ratio had stayed above 2.2 at all times.

In another study-the first of its type, according to the authors-Harvard Medical School and Joint Commission researchers evaluated the quality of care given to patients with congestive heart failure, heart attack, or pneumonia. In 2004 hospitals began reporting their performance on 10 measures related to these three diseases as a condition of receiving Medicare payment increases.

Researchers examined six months of data from 4,000 hospitals. Three-quarters of the patients received the recommended care, such as aspirin therapy for those with heart attack or oxygenation testing for those with pneumonia. Hospitals having more RNs performed better than those employing more LPNs. The researchers also devised measures to evaluate two "underlying domains of quality," treatment-diagnosis and counseling-prevention. Again, hospitals with more RNs as opposed to LPNs performed better. The researchers note, "Nurses, as the primary caregivers for hospitalized patients, provide a crucial link between physicians and patients, and high levels of nurse staffing also allow for more counseling and other duties to be performed by nurses.