Clinical utility of neutrophil-to-lymphocyte ratio in the assessment of asthma and its severity

Homoeostasis of the immune system is regulated by cell-mediated immune-inflammatory responses. The shift of the immune response is clearly reflected by the cellular ratios than individual cell count. Neutrophil-to-lymphocyte ratio (NLR) serves as a good cell-based marker of inflammation, which is being investigated in various inflammation-related diseases. Asthma which is a chronic inflammatory airway disease associated with hyperresponsiveness, recurrent attacks, wheezing, coughing and chest tightness coupled with multicellular influx of granulocytes with mild-to-severe symptoms of and altered NLR. The aim of the present study was to explore the existing literature on NLR in asthma to realise its clinical utility in asthma and its severity. We searched online database resources 'PubMed' and 'Google Scholar' up till now (20th May, 2022), and studies were included as per eligibility criteria. The data collected were reviewed and analysed. The study included eight published articles on NLR and asthma. The analysis revealed that there is a significant difference in mean NLR between healthy controls and asthma patients (1.57 ± 0.35 vs. 2.36 ± 0.30; P < 0.0001); further, severe versus non-severe asthma cases showed the highest mean NLR as compared to non-severe cases (4.82 ± 2.85 vs. 2.13 ± 0.17; P < 0.0001). Receiver operating curve analysis of NLR showed excellent discriminating capacity, for health versus disease and controlled versus uncontrolled. This mini review suggests NLR can serve as a non-expensive, non-invasive monitoring tool to reduce the risk of exacerbation and hospitalisation. However, large studies are warranted.