Problem
Nurses are the largest healthcare profession in the world, and shortages of nurses are a global problem. England has faced a chronic nursing shortage for years. Without hard evidence, it is difficult for hospitals to know where to focus their efforts or for policymakers to make the case for investment in qualified nursing staff. Our research set out to shed light on this.
Science
We linked electronic staff roster data to electronic patient records for one large NHS hospital group in England, covering a dataset covered 52 adult inpatient wards, around 4,500 unique nursing staff, 44,000 patients and 3.5 million hours of patient care. We measured staffing as the gap between the number of nurse hours planned for each ward each day and the number worked. Because rosters are set two to three months in advance, day-to-day shortfalls are driven by absences and vacancies rather than by responses to patient need, which allows us to treat them as effectively random. We tested this assumption extensively and found no evidence that wards adjusted staffing in response to patient severity. We examined the impact of shortfalls separately for registered nurses, who hold a university-level qualification, and nursing assistants, who do not. We also measured how long each nurse had worked at the hospital, as a measure of the knowledge and skills built up by working in a particular organisation.
Outcome
The absence of a registered nurse raises the odds of a patient death by approximately 10% for the average ward. The absence of a nursing assistant has no effect on patient mortality. Shortfalls also increase the likelihood that a patient is transferred to an intensive care unit. Experience matters as much as numbers: each additional year of hospital-specific experience among registered nurses reduces the odds of a patient death by 8%, the equivalent of adding three-quarters of an extra qualified nurse to the ward. Nursing assistants show no such experience effect.
Change
These findings challenge two directions in NHS workforce policy. First, they do not support the drive to replace qualified nurses with nursing assistants: the two groups are not interchangeable, and only qualified nurses affect patient survival. Second, they show that retaining experienced nurses matters as much as recruiting new ones. Every year of hospital experience among registered nurses is worth three-quarters of an additional nurse in terms of lives saved. NHS trusts and the Department of Health and Social Care should treat high turnover among qualified nurses as a patient safety issue, not just a workforce cost. Investing in the retention of experienced registered nurses, and in early-detection protocols for conditions such as sepsis, are among the most cost-effective steps available to reduce preventable deaths in English hospitals.
Elaine Kelly, Health Foundation and Institute for Fiscal Studies; Carol Propper, ³Ô¹ÏºÚÁÏ College Business School, Monash University and Institute for Fiscal Studies; Ben Zaranko, Institute for Fiscal Studies
'Nursing shortages and patient outcomes', Journal of Health Economics, vol. 105, 2026, article 103082; and 'Nurse staffing and inpatient mortality in the English National Health Service: a retrospective longitudinal study', BMJ Quality and Safety, vol. 32, no. 5, 2023, pp. 254–263