Background and Aim
The complete blood cell count(CBC) and peripheral blood smear were the most commonly ordered tests for the diagnosis of neonatal sepsis for many years. Delta neutrophil index(DNI) shows leucocyte differentiation and calculated while CBC is performed. We aimed to evaluate the value of DNI in the diagnose of neonatal sepsis.
Patients were grouped as sepsis group including proven sepsis and clinical sepsis, and control group. DNI was measured with Siemens Advia 2120 and 2120i devices. DNI was calculated as (neutrophil and eosinophil count in myeloperoxidase channel)-(polymorphonuclear leucocyte count in nuclear lobularity channel).
Study population included 228 neonates. Gestational age, birthweight, DNI work-up day and delivery route were similar between group I and II (p > 0.05). Gram negative and positive sepsis were diagnosed in 60 and 50 patients, respectively.
Median DNI (16.3 vs 1,4) and CRP (6.8 vs 0,03 mg/dl) were significantly higher in sepsis group. Proven sepsis group had significantly higher DNI level than clinical sepsis group (20.8 vs 9.1). Patients with gram negative sepsis had significantly higher DNI (30.8 vs 14.9) than gram positive sepsis whereas CRP levels were similar (8 vs 9.3 mg/dl). DNI was insignificantly higher in late sepsis group than early sepsis group (19.8 vs 11.1) whereas CRP was significantly higher in late sepsis group (9.9 vs 0.67 mg/dl). DNI levels were compared according to birthweight as < 1500 g (n:122) and ≥ 1500 (n:105) and found similar (8.9 vs 7.2).
Cut-off levels of DNI and CRP for sepsis were 4.6 (AUC 0.88) and 0.58 mg/dl (AUC 0.90). Fifty five patients (40.7%) in sepsis group were died. Patients with mortality had significantly higher DNI levels than survivors in sepsis group (median, 30.1 vs 9.6). Cut-off level of DNI for mortality prediction was 16.1 with 75% sensitivity, 65% specificity, 65% PPV and 78% NPV (AUC 0.65). DNI levels normalized in 6-10 days with treatment (median, 16.3 to 4.2).
Early diagnosis and treatment are needed to improve morbidity and mortality of neonatal sepsis. There is no perfect marker and most of the markers were unable to use all over the world. To the best of our knowledge, there is only one study with DNI in neonatal sepsis. Lee et al. reported that mean DNI was significantly higher in sepsis group (n:24) and 72th hour DNI level was correlated with mortality. Cut-off level for mortality was 12 with 81% sensitivity and 87% specificity.a
Delta neutrophil index was mostly studied in pediatric and adult population and was evaluated in diagnosis of sepsis, meningitis, peritonitis, urinary tract infection,pneumonia; in differentiating septic arthritis from acute gout attack; and mortality prediction in these conditions. Park et al. performed a systematic review and meta-analysis and concluded that DNI is a potentially useful diagnostic and predictive tool in sepsis.b
In conclusion, we suggest that DNI is useful for early diagnosis, differentiation of etiology, evaluation of treatment efficiency and mortality prediction in neonatal sepsis without any extra blood requirement to CBC study.
aLee SM, Eun HS, Namgung R, et al., Usefulness of the delta neutrophil index for assessing neonatal sepsis. Acta Paediatr, 2013. 102(1): p. e13-16.
bPark JH, Byeon HJ, Lee KH, et al., Delta neutrophil index (DNI) as a novel diagnostic and prognostic marker of infection: a systematic review and meta-analysis. Inflamm Res, 2017. 66(10): p. 863-870.