Effects of nurse staffing ratios on patient mortality in Taiwan acute care hospitals: a longitudinal study.

BACKGROUND The nurse workload in Taiwan averages two to seven times more than that in the United States and other developed countries. Previous studies have indicated heavy nursing workload as an underlying cause of preventable patient death. No studies have yet explored the relationship between nurse staffing ratio and patient mortality in Taiwan. PURPOSE This study explored the effect of nurse staffing ratios on patient mortality in acute care hospitals in Taiwan and considered the implications in terms of policy. METHODS Using stratified random sampling, 108 hospital nursing units in 32 of Taiwan's 441 accredited Western medicine district/regional hospitals and medical centers were included in the study. Variables were retrospectively measured from 108 wards by using monthly data during a 7-month period. A generalized estimating equation logistic model was used to obtain more precise estimates of the nurse staffing effect by controlling for hospital characteristic and patient acuity variables. RESULTS The population-averaged odds ratio for the incidence of death between the low and high patient-nurse ratio groups was 3.617 (95% CI = [1.930, 6.776]). The risk of death in the high patient-nurse ratio group was significantly higher than in the low patient-nurse ratio group. CONCLUSIONS Nurse staffing levels affect patient outcomes. Faced with the problem of inadequate nurses for hospital healthcare needs, Taiwanese policymakers should work to implement a legislatively mandated minimum patient-nurse ratio on a shift-by-shift basis to regulate nurse staffing. In setting guidelines for nurse staffing, policymakers must consider nursing staff characteristics in addition to the number of nurses.