Poor nurse staffing has long been recognized as a patient safety issue. This analysis of three UK National Health Service hospitals examined the differences in in-hospital deaths among different nursing team sizes and compositions. Researchers identified higher inpatient mortality with higher nurse staffing and seniority levels (i.e., more registered nurses [RNs]) but no changes in mortality related to health care support workers (HCSW). Authors surmised that HCSWs may not be a substitute for RNs.