Rationale: Nurse-to-nurse familiarity at work should strengthen the components of teamwork and enhance its efficiency. However, its impact on patient outcomes in critical care remains poorly investigated. Objectives: To explore the role of nurse-to-nurse familiarity on inpatient deaths during ICU stay. Methods: This was a retrospective observational study in eight adult academic ICUs between January 1, 2011 and December 31, 2016. Measurements and Main Results: Nurse-to-nurse familiarity was measured across day and night 12-hour daily shifts as the mean number of previous collaborations between each nursing team member during previous shifts within the given ICU (suboptimal if <50). Primary outcome was a shift with at least one inpatient death, excluding death of patients with a decision to forego life-sustaining therapy. A multiple modified Poisson regression was computed to identify the determinants of mortality per shift, taking into account ICU, patient characteristics, patient-to-nurse and patient-to-assistant nurse ratios, nurse experience length, and workload. A total of 43,479 patients were admitted, of whom 3,311 (8%) died. The adjusted model showed a lower risk of a shift with mortality when nurse-to-nurse familiarity increased in the shift (relative risk, 0.90; 95% confidence interval per 10 shifts, 0.82-0.98; P = 0.012). Low nurse-to-nurse familiarity during the shift combined with suboptimal patient-to-nurse and patient-to-assistant nurse ratios (suboptimal if >2.5 and >4, respectively) were associated with increased risk of shift with mortality (relative risk, 1.84; 95% confidence interval, 1.15-2.96; P < 0.001). Conclusions: Shifts with low nurse-to-nurse familiarity were associated with an increased risk of patient deaths.
Keywords: ICU organization; nurse-to-nurse familiarity; outcome; staffing; team composition.