The association between nurse staffing level and length of stay in general ward and intensive care unit in Korea

Background: Although many studies investigating the relationship between nurse staffing and quality of care have been published, the appropriate nurse-to-patient ratio with patient severity considered remains poorly understood. The aim of this study was to evaluate the impact of nurse staffing levels on length of stay (LOS) in the intensive care unit (ICU) and general ward. Methods: This study used a retrospective cohort study. The nurse staffing level was classified into nine grades for ICU based on a nurse-to-bed ratio, and eight grades for general wards based on a nurse-to-patient ratio. A generalized estimating equation model was used to evaluate the associations between the nurse staffing level and LOS. Subgroup analysis was conducted to assess these associations according to patient nursing needs at each hospital type. Results: This study included 13,135 ICU patients and 263,818 patients admitted to the general ward. In the ICU, the level of nurse staffing (based on the nurse-to-bed ratio) in grade 4 and above (grade 2: <0.63, grade 3: <0.77, grade 4: <0.88) was significantly associated with reduced LOS compared to grade 7 (<1.25). In the general ward, the level of nurse staffing in grade 4 and above was linked to reduced LOS compared to grade 7. Conclusion: The results of this study show that an appropriate nurse-to-patient ratio is associated with a shorter LOS. In particular, hospitals with a higher proportion of severely ill patients require a larger staff of nurses, making it necessary to develop standards for determining nurse staffing level with patient severity taken into account.