Effects of Nurse Staffing Level on In-hospital Mortality and 30-day Mortality after Admission using Korean National Health Insurance Data

간호사 확보수준이 입원 환자의 병원사망과 입원 30일 이내 사망에 미치는 영향

Purpose: The purpose of this study is to investigate the association between the nurse staffing level and the patient mortality using Korean National Health Insurance data. Methods: The data of 1,068,059 patients from 913 hospitals between 2015 and 2016 were analyzed. The nurse staffing level was categorized based on the bed-to-nurse ratio in general wards, intensive care units (ICUs), and hospitals overall. The x² test and generalized estimating equations (GEE) multilevel multivariate logistic regression analyses were used to explore in-hospital mortality and 30-day mortality after admission. Results: The in-hospital mortality rate was 2.9% and 30-day mortality after admission rate was 3.0%. Odd Ratios (ORs) for in-hospital mortality were statistically lower in general wards with a bed-to-nurse ratio of less than 3.5 compared to that with 6.0 or more (OR=0.72, 95% CI=0.63~0.84) and in ICUs with a bed-to-nurse ratio of less than 0.88 compared to that with 1.25 or more (OR=0.78, 95% CI=0.66~0.92). ORs for 30-day mortality after admission were statistically lower in general wards with a bed-to-nurse ratio of less than 3.5 compared to that with 6.0 or more (OR=0.83, 95% CI=0.73~0.94) and in ICUs with a bed-to-nurse ratio of less than 0.63 compared to that with 1.25 or more (OR=0.85, 95% CI=0.72~1.00). Conclusion: To reduce the patient mortality, it is necessary to ensure a sufficient number of nurses by improving the nursing fee system according to the nurse staffing level.