Higher nurse staffing levels associated with reductions in unplanned readmissions to intensive care or operating theatre, and in postoperative in-hospital mortality in heart surgery patients.

Implications for practice and research: Higher nurse staffing levels for postoperative care of cardiac surgery patients reduces the risk of unplanned re-admission to the intensive care or operating theatre and in-hospital mortality. Larger international studies are needed to assess the effect of nurse staffing levels and risk of hospital-wide adverse events.