Journal Review

Fewer nurses mean more hospital patient deaths

Deadly outcomes, staff burnout linked to shortage

Aiken LH, Clarke SP, Sloane DM, et al. Hospital nurse staffing and patient mortality, nurse burn-out, and job dissatisfaction. JAMA 2002; 288:1,987-1,993.

In hospitals with high patient-to-nurse ratios, surgical patients experience higher risk-adjusted 30-day mortality and failure-to-rescue rates (deaths following complications), the authors found. Exacerbating the problem, high patient-to-nurse ratios also translate to nursing burnout and job dissatisfaction, they reported. The findings have important implications for two national issues: patient safety and the hospital nursing shortage. "Our results document sizable and significant effects of registered nurse staffing on preventable deaths," the authors noted. "The association of nurse staffing levels with the rescue of patients with life-threatening conditions suggests that nurses contribute importantly to surveillance, early detection, and timely interventions that save lives."

Moreover, the benefits of improved registered nurse staffing also extend to the larger numbers of hospitalized patients who are not at high risk for mortality but nevertheless are vulnerable to a wide range of unfavorable outcomes.

"Improving nurse staffing levels may reduce alarming turnover rates in hospitals by reducing burnout and job dissatisfaction, major precursors of job resignation," they emphasized. "When taken together, the impacts of staffing on patient and nurse outcomes suggest that by investing in registered nurse staffing, hospitals may avert both preventable mortality and low nurse retention in hospital practice."

The researchers conducted a cross-sectional analysis of several data sets, including a survey of 10,184 staff nurses; records of 232,342 general, orthopedic, and vascular surgery patients discharged from the hospital; and administrative data from 168 nonfederal adult general hospitals in Pennsylvania. After adjusting for patient and hospital characteristics (size, teaching status, and technology), each additional patient per nurse was associated with a 7% increase in the likelihood of dying within 30 days of admission and a 7% increase in the odds of failure to rescue.

After adjusting for nurse and hospital characteristics, each additional patient per nurse was associated with a 23% increase in the odds of burnout and a 15% increase in the odds of job dissatisfaction. "Registered nurses constitute an around-the-clock surveillance system in hospitals for early detection and prompt intervention when patients’ conditions deteriorate," the authors found.

"The effectiveness of nurse surveillance is influenced by the number of registered nurses available to assess patients on an ongoing basis. Thus, it is not surprising that we found nurse-staffing ratios to be important in explaining variation in hospital mortality.

"In a sample of 168 Pennsylvania hospitals in which the mean patient-to-nurse ratio ranged from 4:1 to 8:1, 4,535 of the 232,342 surgical patients [with selected clinical characteristics] died within 30 days of being admitted. The results indicated that had the patient-to-nurse ratio across all Pennsylvania hospitals been 4:1, possibly 4,000 of these patients may have died, and had it been 8:1, more than 5,000 of them may have died.

"While this difference of 1,000 deaths in Pennsylvania hospitals across the two staffing scenarios is approximate, it represents a conservative estimate of preventable deaths attributable to nurse staffing in the state," the authors concluded.