Nurse staffing impact on quality of care in nursing homes: a systematic review of longitudinal studies.

BACKGROUND The relationship between nurse staffing and quality of care (QoC) in nursing homes continues to receive major attention. The evidence supporting this relationship, however, is weak because most studies employ a cross-sectional design. This review summarizes the findings from recent longitudinal studies. METHODS In April 2013, the databases PubMed, CINAHL, EMBASE, and PsycINFO were systematically searched. Studies were eligible if they (1) examined the relationship between nurse staffing and QoC outcomes, (2) included only nursing home data, (3) were original research articles describing quantitative, longitudinal studies, and (4) were written in English, Dutch, or German. The methodological quality of 20 studies was assessed using the Newcastle-Ottawa scale, excluding 2 low-quality articles for the analysis. RESULTS No consistent relationship was found between nurse staffing and QoC. Higher staffing levels were associated with better as well as lower QoC indicators. For example, for restraint use both positive (ie, less restraint use) and negative outcomes (ie, more restraint use) were found. With regard to pressure ulcers, we found that more staff led to fewer pressure ulcers and, therefore, better results, no matter who (registered nurse, licensed practical nurse/ licensed vocational nurse, or nurse assistant) delivered care. CONCLUSIONS No consistent evidence was found for a positive relationship between staffing and QoC. Although some positive indications were suggested, major methodological and theoretical weaknesses (eg, timing of data collection, assumed linear relationship between staffing and QoC) limit interpretation of results. Our findings demonstrate the necessity for well-designed longitudinal studies to gain a better insight into the relationship between nurse staffing and QoC in nursing homes.