Nurse staffing levels, missed vital signs observations and mortality in hospital wards

The NHS in England, like many other healthcare systems, is facing intense pressure to maintain the quality and safety of care provided in hospitals at the same or less cost than in previous years. The quality of nursing care - and the potential for inadequate nursing care to do patients great harm - has emerged as a factor in several reports into failings in NHS hospitals. These reports have often noted that failing to ensure adequate nurse staffing was an important issue that was associated with poor care and preventable deaths. This is consistent with research showing associations between low levels of nurse staffing and increased death rates in hospitals. However, because nurse staffing is only one factor affecting a patient’s death, it is difficult to use these studies to directly show the effects of low staffing on nursing care delivery and to help decide the best staffing levels. Recently studies have begun to explore “missed nursing care”, defined as nursing care that was needed but not done, as a key factor leading to negative patient outcomes. Missed opportunities to observe and act on deterioration of the patient’s condition are thought to be important factors in preventable hospital deaths.

Previous studies on missed nursing care have relied on nurses to report the care they missed. This may not be entirely accurate. This study aims to explore how nurse staffing levels are related to missed or delayed vital signs observation (that is, measurements of blood pressure, pulse and respirations) using direct measures of the timing of observations recorded in a clinical information system. The study will also look at the relationship between staffing levels and possible consequences of missed observations in terms of cardiac arrest calls, unanticipated admission to intensive care and death.

This study will use information about ward and shift level nurse staffing, vital signs observations and patient outcomes that are routinely recorded in a hospital. Information will be gathered from all acute general inpatient wards in Portsmouth Hospitals NHS Trust (PHT). Information from approximately 100,000 nursing shifts will be available for the study. Relationships between registered nurse and health care assistant staffing levels and outcomes will be explored using statistical models which can give a picture of relationships showing, for example, how much the risk of missing a set of observations is increased for every additional patient cared for by a nurse. These estimates will be used to estimate staffing required on different wards to achieve satisfactory levels of compliance with vital signs observations. We will look at the costs and consequences of different levels and mix of nursing staff to achieve this consistently. The study will give guidance on the relative importance and costs of different nursing skill mixes and staffing levels in achieving consistent observations and safe care.