Summary
The association of nursing staffing with patient outcomes has primarily been studied by comparing high to low staffed hospitals, raising concern other factors may account for observed differences. Authors examine the association of inpatient mortality with patients’ cumulative exposure to shifts with low registered nurse (RN) staffing, low nursing support staffing and high patient turnover. Authors used cumulative counts of exposure to shifts with low staffing and high patient turnover as time-varying covariates in survival analysis of data from a three-campus U.S. academic medical center for 2007–2012. Staffing below 75% of annual median unit staffing for each staff category and shift type was characterized as low. High patient turnover per day was defined as admissions, discharges and transfers 1 SD above unit annual daily averages.
Models included cumulative counts of patient exposure to shifts with low RN staffing, low nursing support staffing, both concurrently and high patient turnover. The HR for exposure to shifts with low RN staffing only was 1.027, low nursing support only, 1.030 and shifts with both low, 1.025. For a model examining cumulative exposure over the second to fifth days of an admission, the HR for exposure to shifts with low RN staffing only was 1.048, low nursing support only, 1.032 and for shifts with both low, 1.136. No relationship was observed for high patient turnover and mortality. Authors concluded low RN and nursing support staffing were associated with increased mortality. The results should encourage hospital leadership to assure both adequate RN and nursing support staffing.