https://orcid.org/0000-0002-9001-1525
Dear editor
We appreciate the work of Sun et al,Citation1 who observed that Neutrophil Lymphocyte Ratio (NLR) can be an effective marker for predicting Non Invasive Ventilation (NIV) failure in Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD). They also observed that NLR >8.9 had higher risk of NIV failure requiring intubation. However, we raise some points for further clarification.
NLR gets elevated in AECOPD compared with stable state. Serial monitoring of NLR can predict NIV failure better than single measurement.Citation2 NLR is an independent risk factor for 28-day mortality in patients with AECOPD,Citation2 and the mortality rate increases with NLR ≥4.Citation3 We are curious to know whether continual monitoring of NLR was done and compared with that of stable state in the same patient. In addition, it would be interesting to know whether they assessed mortality outcome, given that the length of hospital stay was observed already.
NLR encompasses both neutrophilia and lymphopenia, the indicators of inflammation and decreased immune response, respectively. Thus, it can reflect the severity of COPD better than when neutrophilia or lymphopenia are monitored alone. Another novel inflammatory marker, PLR (serum absolute count ratio of platelet to lymphocyte) can help predict the severity of clinical condition and mortality in AECOPD patients.Citation3
The authors observed respiratory rate and arterial blood gas analysis. We are curious to know whether they used simple bedside parameters or scores predictive of NIV failure such as initial high respiratory rate, low PaO2/FiO2 ratio, HACOR score >5 at the end of 1 hour of NIV, and initial hs-CRP.Citation4
Individuals with comorbidities and decreased functional capabilities are at higher risk for NIV failure. Patients with poor baseline performance status and having higher DECAF (dyspnea, eosinopenia, consolidation, acidemia, atrial fibrillation) score on admission can predict severity of acute clinical deterioration.Citation5 We wonder whether they had a scope to observe those in their study.
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The authors report no conflicts of interest in this communication.
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References
- Sun W, Luo Z, Jin J, Cao Z, Ma Y. The neutrophil/lymphocyte ratio could predict noninvasive mechanical ventilation failure in patients with acute exacerbation of chronic obstructive pulmonary disease: a retrospective observational study. Int J Chron Obstruct Pulmon Dis. 2021;16:2267–2277. Erratum in: Int J Chron Obstruct Pulmon Dis. 2023;18:3047–3048. doi:10.2147/COPD.S320529
- Yang L, Gao C, He Y, et al. The neutrophil-to-lymphocyte ratio is associated with the requirement and the duration of invasive mechanical ventilation in acute respiratory distress syndrome patients: a retrospective study. Can Respir J. 2022;2022:1581038. doi:10.1155/2022/1581038
- Allena N, Khanal S, Jog A, et al. Decoding the Chronic Obstructive Pulmonary Disease (COPD) Puzzle: investigating the significance of exacerbation scores in triage decision-making. Cureus. 2023;15(7):e41975. doi:10.7759/cureus.41975
- Mathen PG, Kumar KG, Mohan N, et al. Prediction of noninvasive ventilation failure in a mixed population visiting the emergency department in a Tertiary Care Center in India. Indian J Crit Care Med. 2022;26(10):1115–1119. doi:10.5005/jp-journals-10071-24338
- Echevarria C, Steer J, Bourke SC. Comparison of early warning scores in patients with COPD exacerbation: DECAF and NEWS score. Thorax. 2019;74(10):941–946. doi:10.1136/thoraxjnl-2019-213470