Nurse staffing levels, quality and outcomes of care in NHS hospital wards: what does the evidence say?

There is ample evidence demonstrating associations between nurse staffing levels in hospital wards and important patient and staff outcomes. Reviews have concluded that the evidence is consistent with low registered nurse staffing causing worse outcomes. But much of the evidence is from health systems that are very different to the NHS and gives little indication of the actual staffing levels that should be deployed. This evidence brief considers evidence specifically derived from the NHS, which identifies the levels of staffing on wards that were associated with the outcomes reported