Associations between nurse understaffing and HAIs. When the number of RNs on hospital units falls below median levels for two consecutive shifts, patients are 15% more likely to experience hospital-acquired infections (HAIs), including pneumonia and urinary tract and bloodstream infections, according to a study conducted in a large New York City urban hospital system that appeared in the May Journal of Nursing Administration. Comparable shortages of nursing support staff, such as LPNs, result in 11% more patients incurring HAIs. When understaffing (defined in the study as below 80% of median levels) is continuous, the resulting heavy workloads of nurses may compromise infection prevention practices and cause early signs of infection to be missed. Such ongoing understaffing also stresses nurses, which can negatively impact patient care.