Prognostic value of lymphocyte count for in-hospital mortality in patients with severe AECOPD

(2022) 22:376 Hu et al. BMC Pulmonary Medicine https://doi.org/10.1186/s12890-022-02137-1 Open Access RESEARCH Prognostic value of lymphocyte count for in‑hospital mortality in patients with severe AECOPD Yanlu Hu1 , Huanyu Long1 , Yang Cao2   and Yanfei Guo1*    Abstract Background: Patients with severe acute exacerbations of chronic obstructive pulmonary disease often have a poor prognosis. Biomarkers can help clinicians personalize the assessment of different patients and mitigate mortality. The present study sought to determine if the lymphocyte count could act as a risk factor for mortality in individuals with severe AECOPD. Methods: A retrospective study was carried out with 458 cases who had severe AECOPD. For analysis, patients were divided into two groups on the basis of lymphocyte count: < 0.8 × 109/L and ≥ 0.8 × 109/L. Results: Patients who fulfilled the criteria for inclusion were enrolled, namely 458 with a mean age of 78.2 ± 8.2 years. Of these patients, 175 had a low lymphocyte count. Compared to patients with normal lymphocyte counts, those with low counts were older (79.2 ± 7.4 vs. 77.5 ± 8.6 years, p = 0.036), had lower activities of daily living scores on admission (35.9 ± 27.6 vs. 47.5 ± 17.1, p < 0.001), and had a greater need for home oxygen therapy (84.6 vs. 72.1%, p = 0.002). Patients with low lymphocytes had higher mortality rates during hospitalization (17.1 vs. 7.1%, p = 0.001), longer hospital stay (median [IQR] 16 days [12–26] vs. 14 days [10–20], p = 0.002) and longer time on mechanical ventilation (median [IQR] 11.6 days [5.8–18.7] vs. 10.9 days [3.8–11.6], p < 0.001). The logistic regression analysis showed lymphocyte count < 0.8 × 109/L was an independent risk factor associated with in-hospital mortality (OR 2.74, 95%CI 1.33–5.66, p = 0.006). Conclusion: Lymphocyte count could act as a predictor of mortality in patients with severe AECOPD. Keywords: Exacerbation, Chronic obstructive pulmonary disease, Lymphocyte count, Mortality, Biomarker Background Chronic obstructive pulmonary disease (COPD) is a global epidemic with a high incidence of morbidity and mortality, often resulting in a poor prognosis for patients. Acute exacerbation of COPD (AECOPD) occurs when respiratory problems get worse, resulting in the need for *Correspondence: 1 Department of Respiratory and Critical Care Medicine, Beijing Hospital, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, P.R. China Full list of author information is available at the end of the article further clinical treatment, and it often becomes a critical condition with poor prognosis [1]. At present, according to the World Health Organization (WHO), COPD is the third leading cause of death in the world [2]. The latest epidemiological survey of COPD in China shows that the prevalence of COPD among people aged 40 and above is as high as 13.7%, and there are currently an estimated 100 million cases of COPD in China [3]. AECOPD is one of the leading causes of hospitalization, which significantly increases the mortality rate of AECOPD patients [4]. Early identification of risk factors for poor prognosis can © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Hu et al. BMC Pulmonary Medicine (2022) 22:376 help stratify patient management and reduce mortality, readmission rates and the socioeconomic burden [5]. Patients with AECOPD have significant individual differences, and it is sometimes difficult for clinicians to perform an accurate prognostic analysis. Early identification of risk factors associated with poor prognosis in AECOPD can effectively help clinicians to develop individualized treatment plans for patients with AECOPD. Old age, dyspnea and having comorbidities have been shown to be predictors of poor prognosis for AECOPD [6–8]. There is still a need for more biomarkers in clinical practice to analyze the condition of AECOPD patients and intervene early in the prognosis. Lymphocytes are associated with human immune function and inflammatory status [9]. Currently, the predictive role of lymphocytes on the prognosis of AECOPD is unclear and fewer studies have been conducted in this field. In a three-year prospective study, Acanfora found that a relative lymphocyte count ≤ 20% was an independent risk factor for mortality within three years in elderly patients with severe COPD [10]. However, lymphocyte percentage was influenced by other leukocyte subpopulations, and other outcome variables in patients with AECOPD were not described in the study. Accordingly, we aimed to elucidate the association between low lymphocyte count and in-hospital mortality, length of stays and use time on ventilator during hospitalization in severe AECOPD patients. Methods Study design and patients Patients aged 40 years and above who were admitted to Beijing Hospital for treatment of severe AECOPD from January 2011 to September 2021 were included. AECOPD was considered aggravated dyspnea with an increase in cough and/or amount of sputum or its purulent appearance, needing more care [1]. All diagnoses, namely the primary and five secondary diagnoses, were based on the International Classification of Diseases, 10th Revision (ICD10) coding system. Exclusion criteria for the study were length of stay of less than 24 h or readmission within one month. And cases who had been admitted for AECOPD in the month prior to the current admission were also excluded. Our study was conducted in accordance with the Declaration of Helsinki and with approval from the Ethics Committee of Beijing Hospital (BJ-2018-199). In this study, severe AECOPD was defined as AECOPD requiring admission to the intensive care unit (ICU) and to the general respiratory ward during hospitalization with a diagnosis of respiratory failure or requiring mechanical ventilation. The patient’s Page 2 of 7 laboratory test results were obtained from the first examination with (...truncated)