Mortality in patients resuscitated from out-of-hospital cardiac arrest based on automated blood cell count and neutrophil lymphocyte ratio at admission.

INTRODUCTION: The neutrophil lymphocyte ratio(NLR) is a marker of systemic inflammation. We hypothesized that admission NLR is related to mortality and that epinephrine application during resuscitation influences NLR in patients after successful resuscitation from out of hospital cardiac arrest (OHCA).
METHODS: This retrospective cohort study is based on a registry including all OHCA patients who had a presumed cardiac cause of cardiac arrest and achieved sustained ROSC prior to admission between 2005 and 2014. Patients were categorized into three groups according to the calculated NLR at admission (NLR <6, ≥6, and 'abnormal differential' indicating no differential blood cell count on patients report due to exceedance of machine predefined parameter limits). The primary outcome measure was long-term mortality after OHCA. Cox proportional hazards models were used for multivariable analysis.
RESULTS: Out of 2273 OHCA patients during the study period a total of 1188(52%) patients were eligible for analysis, of those 274(23%) were female and mean age was 64 (25-75 IQR:52-72). Compared to a NLR<6 (n=442), adjusted hazard ratio for long-term mortality was significantly higher in patients with a NLR≥6 (n=447; 1.52 (95%CI 1.03-2.24)) and in patients with abnormal differential (n=299; 3.16 (95%CI 2.02-4.97)). Epinephrine application during resuscitation did not explain the effect of NLR on mortality.
CONCLUSION: In this large retrospective cohort study of altogether >1000 OHCA patients, hospital admission NLR<6 compared to abnormal differential or NLR≥6 was associated with mortality independently from epinephrine application.