The aim of this study was to evaluate the use of neutrophil/lymphocyte ratio (NLR) instead of
procalcitonin for bacteremia diagnosis.
Material and Method: The investigation was conducted retrospectively with 2710 patients obtained
from the laboratory information system. Neutrophil and lymphocyte counts were recorded from
laboratory complete blood count parameters, and the NLR values were calculated. NLR cut-off values
were determined based on procalcitonin of 0.1, 1, 2, and 5 ng/mL as cut-off values. Positive and
negative predictive NLR values were established at different cut-off concentrations. Receiver operating characteristic (ROC) curves were plotted, and the areas under the ROC curves were calculated in order
to evaluate NLR assessment.
Results: NLR cut-off values were based on procalcitonin results of 0.1, 1, 2, and 5 ng/mL with
corresponding NLR cut-off values of 4.71, 6.44, 7.65, and 8.24, respectively. Positive predictive values of
NLR using 4.71, 6.44, 7.65 and 8.24 as the cut-off values were 92.90%, 55.50%, 45.30%, and 27.60%,
respectively. Negative predictive values of NLO using 4.71, 6.44, 7.65 and 8.24 as the cut-off values
were 28.20%, 75.40%, 81.60%, and 88.40%, respectively. Areas under the curve for the four cut-off
values of NLR were 0.706, 0.704, 0.689, and 0.652, respectively (p <0.001).
Conclusion: NLR (instead of procalcitonin) appears to be useful as a parameter for ruling out
bacteraemia using a cut-off value of 6.44.