A quantitative systematic review of the association between nurse skill mix and nursing-sensitive patient outcomes in the acute care setting

Aims: To examine the association between nurse skill mix (the proportion of total hours provided by Registered Nurses) and patient outcomes in acute care hospitals. Design: A quantitative systematic review included studies published in English between January 2000 – September 2018. Data sources: Cochrane Library, CINAHL Plus with Full Text, MEDLINE, Scopus, Web of Science and Joanna Briggs Institute were searched. Observational and experimental study designs were included. Mix-methods designs were included if the quantitative component met the criteria. Review methods: The Systematic Review guidelines of the Joanna Briggs Institute and its critical appraisal instrument were used. An inverse association was determined when seventy-five percent or more of studies with significant results found this association. Results: Sixty-three articles were included. Twelve patient outcomes were inversely associated with nursing skill mix (i.e., higher nursing skill mix was significantly associated with improved patient outcomes). These were length of stay; ulcer, gastritis and upper gastrointestinal bleeds; acute myocardial infarction; restraint use; failure-to-rescue; pneumonia; sepsis; urinary tract infection; mortality/30-day mortality; pressure injury; infections and shock/cardiac arrest/heart failure. Conclusion: Nursing skill mix affected 12 patient outcomes. However, further investigation using experimental or longitudinal study designs are required to establish causal relationships. Consensus on the definition of skill mix is required to enable more robust evaluation of the impact of changes in skill mix on patient outcomes. Impact: Skill mix is perhaps more important than the number of nurses in reducing adverse patient outcomes such as mortality and failure to rescue, albeit the optimal staffing profile remains elusive in workforce planning.