For several decades, researchers in the health services have identified correlations between nursing staff and hospital results. Nevertheless, nursing care and nurse staffing were largely context variables in all of these studies and not the primary subject of research. The National Center for Nursing Studies, the predecessor to the National Institute of Nursing Research, held an invitational conference on patient care research from the viewpoint of nursing practice’s effectiveness in the 1990s. It was hoped that as methods for quantitatively documenting the quality of patient care became more sophisticated, evidence linking the structure of nurse staffing (i.e., hours of service, skill mix) to the quality and safety of patient care.

It has been hypothesized that effective registered nurse staffing affects the efficiency of patient monitoring, as it enables nurses to invest more time in clinical care. Insufficient staffing contributes to time to care rationing which has a direct effect on the incidence of missed treatment. This may be an explanatory factor that connects the nursing staff and patient outcomes such as in-hospital deaths. However, it is unclear how to quantify the nursing workload and how wards will be staffed to provide safe treatment. Ideally, hospital management strives to strike a balance between workload and number of staffed nurses. Patient classification systems (PCSs) have been developed to direct hospital resource allocation and are used by public agencies to assess hospital funding. PCSs provide objective and subjective indicators of patient needs and other aspects of treatment which are difficult to quantify and insufficiently backed by evidence Nurse-to – Patient Ratios (NPRs) are defined as the proportion of nurses available per patient and are used to allocate the available nursing staff through hospital wards. However, the level of treatment or ward features is not taken into account by the NPRs. NPRs estimate the number of nurses required, taking into account the amount of beds occupied on a specific ward.

Many advances in health services, such as modern medical technology and a diminishing average length of stay, have further exacerbated the challenges of today, and have led to a rise in the amount of treatment patients need when they are in healthcare. New medical technology allows many less critically ill patients who would have previously received inpatient surgical treatment to receive outpatient care. Also, patients who may have stayed at the hospital in the early stages of their treatment in the past are being moved into skilled nursing facilities or homes today. Although insufficient staffing rates impose heavy burdens on the nursing staff and adverse outcomes are traumatic for patients, consideration must also be given to significant financial costs. A research sponsored by Agency for Healthcare Research and Quality (AHRQ) found that all adverse events examined (pneumonia, pressure ulcer, UTI, wound infection, fall / injury of the patient, sepsis, and adverse drug event) were correlated with increased costs. For example, care costs increased by 84 per cent for patients who contracted pneumonia while at the hospital. Treatment for pneumonia raised the average cost of care by $22,390-$28,505, although the duration of stay raised by 5.1-5.4 days and the risk of death increased by 4.67-5.5 per cent. Pressure ulcers, another form of patient adverse effects prone to nursing, are estimated to cost $8.5 billion annually. Moreover, the nursing staff’s capability ratio changed as hospitals expanded the number of nurses’ aides. As a result, registered nurses took on more supervisory roles at a time when their patients needed more bedside nursing treatment.

Because of the clear evidence connecting nursing staff with patient outcomes, there has been substantial empirical debate on ward-based compulsory staffing rates Compulsory nursing staffing levels are in place in the state of California (US) and Victoria and Queensland (Australia). However, as there are no evidence-based recommendations for nurse staffing to date, most policymakers and health care organizations are reluctant to endorse a mandatory minimum ward-based approach. In addition, hospital administrators and nurse leaders tend to struggle on a regular basis when allocating qualified nurses to hospital wards taking into account patient acuity and results, nurses’ expertise and level of education, financial factors and ward workflow. It is fair to hypothesize that patient care would improve if there were more nurses available with a suitable skill mix. The most important limitation in current research, however, is that the majority of studies examining nurse staffing and patient outcomes use aggregated data at the hospital level which makes translation to the ward level impossible. Furthermore, it remains unclear which methodology is suitable when measuring nursing staffing and workload.