NEUTROPHIL-TO-LYMPHOCYTE RATIO AS A PREDICTOR OF MORBIDITY AND MORTALITY IN LOW RESOURCE SETTINGS

Background: Alternate laboratory investigations that could be used as prognosis-adjudicating tools or triage aids are either too invasive, or too expensive and therefore not fit to be used in a low-resource setting. The Neutrophil-to-lymphocyte ratio (NLR) is a simple inflammatory marker which is affordable, and can be calculated using a routine Full Blood Count. If a strong predictive effect is found using such lowly tools, it could transform the practice of medicine in the poorly served regions of Sub-Saharan Africa. 
Methods: This study is a retrospective cohort study using secondary-tier healthcare data from Ughelli, Nigeria, and assesses the relationship between NLR and clinical outcomes among 213 participants. Demographic, clinical and haematological data were analysed using correlation and regression analysis. Descriptive statistics were used to summarize the demographic, clinical and haematological characteristics of the study population. Spearman's Rank Order correlation was used to assess the relationship between Neutrophil-to-lymphocyte ratio and selected clinical outcomes. The Mann-Whitney U test was used to compare Neutrophil-to-lymphocyte ratio between patients with shorter hospital stays and longer hospital stays.
Binary logistic regression was performed to determine the factors associated with prolonged hospital stay. Multiple linear regression was also used to assess whether the Neutrophil-to-lymphocyte ratio independently predicted the duration of hospital stay.
Results: The mean NLR was 2.93±1.06. NLR showed a weak positive correlation with duration of hospital stay (r=0.149, p=0.030). A one unit increase in NLR was associated with higher odds of prolonged hospital stay( adjusted OR=2.272,95% Cl:1.349-3.826,p=0.002). However, NLR was not an independent predictor of the exact duration of hospital stay(p=0.088). The small number of deaths limited assessment of NLR as a predictor of mortality.
Conclusion: While a weak but statistically significant relationship was found between higher NLRs and increased morbidity, this reltionship disappeared when controlling for confounders such as the total white blood cell count. The disappearance could suggest that patients who are judged to be very sick are either referred, or self refer to a tertiary facility. Further research into this would be potentially rewarding.