Most hospitals augment their regular nursing staff with temporary nurses. Their use is controversial, however, and some say that supplemental nurses diminish the quality of care and the efficiency and morale of staff nurses. Aiken and colleagues examined supplemental nurses' qualifications and whether their use affected staff nurses' job satisfaction or patient outcomes.

After reviewing data from the 2000 National Sample Survey of Registered Nurses, they found that almost 6% of all hospital nurses had a supplemental staffing agency as either their main or secondary employer. Supplemental nurses were more likely than staff nurses to be male, have a baccalaureate, and work in ICUs; 56% were hospital staff nurses as their primary position and worked per diem as a second job.

Data from a 1999 survey of nurses at 198 Pennsylvania hospitals revealed that supplemental nurses constituted up to 33% of hospital patient care staff. Hospitals that used more temporary nurses had low scores for staffing and resource adequacy, and their staff nurses were more likely to report such adverse patient events as nosocomial infections and falls, and in nurses work-related injuries, verbal abuse, dissatisfaction with their job, and burnout. But when hospitals had fewer resources and lower permanent staffing, employing supplemental staff helped to lower the incidence of medication error, patient complaints, and verbal abuse. These findings suggest that supplemental nurses are well educated and qualified, and in some cases their use helps to mitigate hospital resource deficiencies and improve patient outcomes.

"One purpose of nursing research is to examine the validity of widely held beliefs about nursing practice," says lead study author Linda Aiken. "The belief that temporary nurses are somehow responsible for poor quality care is not justifiable. Our attention should move from being critical about temporary nurses to motivating hospitals that cannot attract and retain enough permanent nurses to improve their practice environments."