A study by the University of Southampton said patients are more likely to die in wards staffed by high numbers of temporary nurses, The Independent reports. The study said the risk of death increased by 12% for every day a patient experienced a high level of temporary staffing. It defined a high level as 1½ hours or more of agency nursing per day. However, while the study found an association between levels of temporary staff and deaths, it could not say what caused the increased risk.