Aims To examine the relationship between breaks and patient safety in Korean hospitals and determine the mediating effect of missed nursing care on this relationship. Background Breaks during working hours can affect patient safety; however, few studies have examined the relationship between breaks and patient safety in hospitals and their findings were conflicting. Methods A cross-sectional online survey was conducted with 399 nurses in Korean hospitals. Multiple linear regression was used to explore the association between breaks, missed nursing care and patient safety. Model 4 of Hayes's (2018) and bootstrapping analysis were employed to identify the mediating effect of missed nursing care. Results Average break time per shift was about 15 min; most participants had breaks of less than 30 min. Missed nursing care was a complete mediator of the relationship between breaks and patient safety. Conclusion Break length has an indirect effect on patient safety, medication errors and falls with injury through missed nursing care. Implications for Nursing Management More discussion is needed to develop policy and mandatory regulations to ensure sufficient breaks and adequate nurse staffing to reduce missed nursing care and enhance patient safety.

To identify the techniques used to measure nurse staffing and to evaluate the reliability, validity and limitations of nursing hours per patient day (NHPPD). Numerous studies have attempted to identify appropriate nurse staffing levels; however, variations in nurse staffing measures may have caused inconsistent findings regarding the relationships between nurse staffing and quality of care. Seventeen studies using nurse staffing measures were reviewed. Six common nurse staffing measures were identified: nurse-to-patient ratios, full-time equivalents, NHPPD, skill mix, nurse-perceived staffing adequacy and nurse-reported number of assigned patients. Among nurse staffing measures, NHPPD is the most frequently used and is considered to be highly beneficial. This measure shows some evidence of high inter-rater reliability. The predictive validity of NHPPD for patient falls is high, whereas that for pressure ulcers is low. For NHPPD to be applied more effectively as a nurse staffing measure, there is a need for additional reliability testing in various types of units with large sample sizes; further validity research for additional patient outcomes; appropriate adjustments in its application to capture variations in the characteristics of nurses, patients and hospital units; and a consistent data collection procedure.