Prevalence of persistent blood eosinophilia: relation to outcomes in patients with COPD

Blood Eosinophil Count and Hospital Readmission in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Purpose

This retrospective, observational cohort study investigated the association of blood eosinophil counts within 1 week of hospitalization for acute exacerbation of COPD (AECOPD) with subsequent risk of all-cause and COPD-related readmission from a large integrated health system.

Patients and Methods

Electronic medical records were extracted for index hospitalization for AECOPD at all Intermountain Healthcare hospitals. The primary outcome was the relationship of blood eosinophil count to 30-day all-cause readmission; secondary outcomes were 60-day, 90-day, and 12-month all-cause readmission, COPD-related readmission, and empiric derivation of the eosinophil count with the highest area under the curve (AUC) for predicting 30-day all-cause readmission.

Results

Of 2445 included patients, 1935 (79%) had a blood eosinophil count <300 cells/µL and 510 (21%) had a count ≥300 cells/µL. Using a 300-cells/μL threshold, there was no significant difference between high and low eosinophil groups in 30-day (odds ratio [OR]=1.05, 95% confidence interval [CI]=0.75–1.47) or 60-day (OR=1.15, 95% CI=0.88–1.51) all-cause readmissions. However, patients with greater (versus lesser) eosinophil counts had increased 90-day and 12-month all-cause readmissions (OR=1.35, 95% CI=1.06–1.72, and OR=1.32, 95% CI=1.07–1.62). COPD-related readmission rates were significantly greater for patients with greater (versus lesser) eosinophil counts at 30, 60, and 90 days and 12 months (OR range=1.52–1.97). A total of 70 cells/µL had the most discriminatory power to predict 30-day all-cause readmission (highest AUC).

Conclusion

Eosinophil counts in patients with COPD were not associated with a difference in 30-day all-cause readmissions. However, greater eosinophil counts were associated with increased risk of all-cause readmission at 90 days and 12 months and COPD-related readmission at 30, 60, and 90 days and 12 months. Patients with eosinophils <70 cells/μL had the lowest risk for 30-day all-cause readmission. Blood eosinophils in patients hospitalized with AECOPD may be a useful biomarker for the risk of hospital readmission.

Eosinophils in COPD-Current Concepts and Clinical Implications

In recent years, heterogeneity in chronic obstructive pulmonary disease (COPD) inflammatory patterns has been recognized as a basis for more precise treatment interventions because current therapies have limited effectiveness. Eosinophilic airway inflammation in COPD has become a subject of research interest as a potential treatment target for inhaled corticosteroid therapy. However, the role of eosinophils in COPD is still unclear, and it is unknown why only some patients with COPD develop eosinophilic airway inflammation. Induced sputum analysis is the most common method of assessing the type of airway inflammation. Accessibility to sputum induction, however, is limited in clinical practice, and blood eosinophils have been proposed to serve as a surrogate marker and treatment guide. Blood eosinophil count has been shown to poorly predict sputum eosinophilia, and, moreover, it seems to be fairly unstable and affected by various factors. Nevertheless, in several trials, blood eosinophil count appeared to predict good response to inhaled corticosteroids However, biologics targeting eosinophils do not appear to be effective in COPD. In this review, we briefly summarize the current knowledge on eosinophils in COPD pathogenesis. Then, we discuss the use of blood eosinophil count in COPD in relation to the recent Global Initiative for Chronic Obstructive Pulmonary Disease recommendations, their ability to predict sputum eosinophilia, and their potential role in guiding treatment.

Role of Type2 Inflammatory Biomarkers in Chronic Obstructive Pulmonary Disease

Airway inflammation in chronic obstructive pulmonary disease (COPD) is typically thought to be driven by Type1 immune responses, while Type2 inflammation appears to be present in definite proportions in the stable state and during exacerbations. In fact, some COPD patients showed gene expression of Type2 inflammation in the airway, and this subset was associated with the inhaled corticosteroid (ICS) response. Interestingly enough, the relationship between COPD and diseases associated with Type2 inflammation from the perspective of impaired lung development is increasingly highlighted by recent epidemiologic studies on the origin of COPD. Therefore, many researchers have shown an interest in the prevalence and the role of existent Type2 biomarkers such as sputum and blood eosinophils, exhaled nitric oxide fraction, and atopy, not only in asthma but also in COPD. Although the evidence about Type2 biomarkers in COPD is inconsistent and less robust, Type2 biomarkers have shown some potential when analyzing various clinical outcomes or therapeutic response to ICS. In this article, we review the existent and emerging Type2 biomarkers with clinically higher applicability in the management of COPD.

Endo-phenotyping of COPD patients

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a heterogeneous syndrome and may comprise several different phenotypes that are driven by different molecular mechanisms (endotypes). Several different clinical, genetic, and inflammatory phenotypes of COPD have been recognized and this may lead to more precise effective therapies.

AREAS COVERED

The different clinical phenotypes, including smoking versus nonsmoking COPD, small airway disease versus emphysema, non-exacerbators versus frequent exacerbators are discussed. Rare genetic endotypes (alpha₁-antitrypsin deficiency, telomerase polymorphisms), and inflammatory phenotypes (eosinophilic versus neutrophilic) are also recognized in stable and exacerbating patients and have implications for the choice of therapy.

EXPERT OPINION

Clinical phenotypes have so far not proved to be very useful in selecting more personalized therapy for COPD. Even with genetic endotypes, this has not led to improved therapy. More promising is the recognition that COPD patients who have increased sputum or blood eosinophils tend to have more frequent exacerbations and inhaled corticosteroids are more effective in preventing exacerbation. Increased blood eosinophils have proved to be a useful biomarker now used to target ICS more effectively. Furthermore, COPD patients with low eosinophils are more likely to get pneumonia with ICS and to have lower airway bacterial colonization.

The stability of blood eosinophils in stable chronic obstructive pulmonary disease: a retrospective study in Belgian primary care

Background

Blood eosinophil counts (BEC) were recently included in the 2019 Global Initiative for Obstructive Lung Disease (GOLD) guideline as an easily accessible theragnostic biomarker for Chronic Obstructive Pulmonary Disease (COPD). However, the stability of BEC remains insufficiently studied.

Methods

We conducted a retrospective study in six primary care practices in Belgium on data from Electronic Health Records of stable COPD patients, to characterise the stability of blood eosinophils over time. We report the percentage of patients with BEC persistently below or above the 2019 GOLD guideline thresholds (100 and 300 cells/μL). For each patient the mean, standard deviation (SD) and relative standard deviation (RSD) of the BEC were calculated to determine the intra-patient variability.

Results

Ninety-eight patients were included, yielding 1082 eosinophil measurements (median 8 measurements/patient), with BEC ranging between 0 and 1504 cells/μL. Four (4.1%) patients had BEC persistently below 100 cells/μL, 34 (34.7%) had measurements persistently above this threshold. Approximately half of the patients (51.0%) had BEC persistently below 300 cells/μL and 3 (3.1%) patients had counts persistently above this threshold. 28.6% of patients crossed both threshold values throughout the registration period. The mean BEC per patient ranged between 15 and 846 cells/μL with an intra-patient SD between 5 and 658 cells/μL. The mean intra-patient RSD was 0.46. There was a significant strong positive correlation (Pearson analyses) between the mean BEC and SD (r = 0.765; n = 98). Simple linear regression was used to further describe the influence of the mean eosinophil count on the SD (B = 0.500; 95%CI 0.415–0.586; n = 98; p < 0.001).

Conclusion

BEC can be variable in individual COPD patients. Therefore, the use of a single measurement to guide therapeutic decisions remains debatable. Further prospective research remains necessary to validate the reproducibility of this biomarker.

Low serum free light chain is associated with risk of COPD exacerbation

Background

Most exacerbations of chronic obstructive pulmonary disease (COPD) are triggered by respiratory tract infections. Adaptive immunity via antibody production is important in preventing infections. Impaired antibody production is reported to be associated with an increased risk of exacerbations of COPD. In the present study, we elucidated whether reduced free light chains (FLCs), which are excessive amounts of light chains produced during antibody synthesis and can be used to estimate systemic antibody production, may be a promising biomarker to predict the risk of exacerbations of COPD.

Methods

We enrolled stable male patients with COPD and prospectively observed them for 2 years. At baseline, serum combined FLC (cFLC; sum of kappa and lambda values) and pulmonary function were evaluated. Exacerbation was defined as a worsening of symptoms requiring treatments with antibiotics, corticosteroids or both.

Results

63 patients with stable COPD were enrolled (72.8±8.1 years, GOLD A/B/C/D=24/28/6/5), and 51 patients completed the 2-year follow-up. Serum cFLC was 31.1 mg·L⁻¹ on average and ranged widely (1.4 to 89.9 mg·L⁻¹). The patients with low cFLC (below the mean−sd, n=6) experienced a significantly shorter time to the first exacerbation of COPD (p<0.0001 by the log-rank test). A multivariate Cox proportional hazard model, including the COPD assessment test score, % predicted forced expiratory volume in 1 s (FEV₁ % pred), and number of previous exacerbations demonstrated that low cFLC and low FEV₁ % pred were independently and significantly correlated with the risk for exacerbations of COPD.

Conclusion

Low cFLC may be a B-cell-associated novel biomarker associated with risk of COPD exacerbation.

Impaired antibody production is associated with an increased risk for exacerbations of COPD. Low serum free light chain is a novel B-cell-associated biomarker for COPD exacerbations.https://bit.ly/35cgMTC

Frequency of Blood Eosinophilia in newly diagnosed Chronic Obstructive Pulmonary Disease patients

Objective:

To determine Blood Eosinophilia frequency in newly diagnosed Chronic Obstructive Pulmonary Disease patients.

Methods:

An observational cross-sectional research on newly diagnosed COPD patients with age ≥ 40 years was performed at Ojha Institute of Chest Diseases, Dow University of Health Sciences Karachi. COPD patients diagnosed in outpatient clinic or admitted in Chest Unit during six-month period from September 2018 to May 2019 were selected. Each patient underwent spirometry, and blood was tested for eosinophilia (≥ 2% eosinophils in blood), after obtaining informed consent and clinical history.

Results:

One hundred and fifty COPD patients were diagnosed and evaluated for Blood Eosinophilia, out of which 86 (57.3%) and 64 (42.7%) patients were Males and Females respectively with mean age of 63.72 ± 10.24 years. Current Smokers were 48 (32.0%), Ex-Smokers 15 (10.0%), and Biomass Exposure was present in 76 (50.7%) of patients. Spirometric severity of COPD was Mild in 11 (7.3%), Moderate in 68 (45.3%), Severe in 59 (39.3%), and Very Severe in 12 (8.0%) patients. Blood Eosinophilia was present in 59 (39.3%) patients of COPD among which majority 43 (72.9%) were having Moderate 24 (40.7%) and Severe 19 (32.2%) COPD respectively.

Conclusion:

Frequency of Blood Eosinophilia in newly diagnosed COPD patients was high, among which most of the COPD patients were moderate to severe.

Blood Eosinophilia and Its Stability in Hospitalized COPD Exacerbations are Associated with Lower Risk of All-Cause Mortality

Purpose

Peripheral blood eosinophilic counts are susceptible to many factors and have variability over time. There are limited studies on association of blood eosinophilia with long-term mortality of chronic obstructive pulmonary disease (COPD) patients and these results remain controversial. Our aims were to explore the association of blood eosinophilia at index hospitalization and stability of blood eosinophilia stability over 5 years with all-cause mortality of patients hospitalized for acute exacerbation of COPD (AECOPD).

Patients and Methods

Eight hundred twenty-nine patients hospitalized for AECOPD between 2013 and 2014 were included in this study and grouped into two groups according to blood eosinophil with 150 cells/μL used as the cutoff value to form eosinophilic and non-eosinophilic groups. Two hundred forty-one COPD inpatients with at least three blood eosinophils measured from different hospitalizations were used for analysis of longitudinally eosinophilic stability and divided into three groups according to the same cutoff value: predominantly (PE), intermittently (IE) and rarely (RE) eosinophilic groups. Cox regression analysis was used to determine the association of blood eosinophilia and all-cause mortality.

Results

In patients hospitalized for AECOPD, 261 (31.5%) at baseline and 41 (17%) based on at least three measurements of blood eosinophils had increased blood eosinophils. For all-cause mortality, eosinophilic COPD patients at index hospitalization had a lower all-cause mortality compared with non-eosinophilic COPD patients (hazard ratio 0.77, 95% confidence interval 0.6–0.99, P=0.04). In patients readmitted for AECOPD by longitudinal eosinophil stability, with the RE group used as reference, the PE group was associated with a lower all-cause mortality of AECOPD patients (hazard ratio 0.43, 95% confidence interval 0.22–0.85, P=0.016), compared to the IE group (hazard ratio 0.72, 95% confidence interval 0.47–1.11, P=0.133).

Conclusion

Patients with increased eosinophils (using eosinophil 150 cells/μL as a cutoff value), especially predominantly increased eosinophil levels based on multiple measurements, had a lower risk of all-cause mortality. Blood eosinophilia can be used as a biomarker in hospitalized COPD exacerbations for predicting the risk of all-cause mortality.

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Elevated blood eosinophils in acute COPD exacerbations: better short- and long-term prognosis

Background: Elevated eosinophils in COPD is recognized as a potential risk factor for exacerbations, but the prognostic role of elevated eosinophils during exacerbations of COPD is unclear. We investigated short-term and long-term outcomes in patients with exacerbations of eosinophilic phenotype, compared with patients with low blood eosinophils. Methods: A single-centre retrospective study of all patients admitted for a COPD exacerbation to Bispebjerg University Hospital in 2010-2011 was established by linking inpatient data with national patient and prescription registries, with a three-year follow-up period. Elevated eosinophils were defined as a blood eosinophil level at admission of ≥0.30 × 10⁹ cells/L. Results: A total of 811 patients were included; 13.2% had an eosinophilic exacerbation. The eosinophilic group had less need for non-invasive ventilation, shorter inpatient stay, and lower in-hospital mortality, compared to the non-eosinophilic group. However, the eosinophilic and non-eosinophilic groups showed similar risks of readmission (incidence rate ratio[95], 0.99 [0.73-1.36]). Three-year mortality was high in both groups, although lower in the eosinophilic group (40% vs. 54%, p = 0.006). Conclusions: COPD exacerbations in patients with high blood eosinophil have a better short-term prognosis without higher risk of subsequent exacerbation. Eosinophilic exacerbations have also a lower three-year mortality.

Blood Eosinophil Counts in Chronic Obstructive Pulmonary Disease: A Biomarker of Inhaled Corticosteroid Effects

Blood eosinophil counts have emerged as a chronic obstructive pulmonary disease (COPD) biomarker that predict the effects of inhaled corticosteroids (ICS) in clinical practice. Post-hoc and prospective analysis of randomized control trials have shown that higher blood eosinophil counts at the start of the study predict a greater response to ICS. COPD patients with frequent exacerbations (2 or more moderate exacerbations/yr) or a history of hospitalization have a greater response to ICS. Ex-smokers also appear to have a greater ICS response. Blood eosinophil counts can be combined with clinical information such as exacerbation history and smoking status to enable a precision medicine approach to the use of ICS. Higher blood eosinophil counts are associated with increased eosinophilic lung inflammation, and other biological features that may contribute to the increased ICS response observed. Emerging data indicates that lower blood eosinophil counts are associated with an increased risk of bacterial infection, suggesting complex relationships between eosinophils, ICS response, and the airway microbiome.

High suPAR and Low Blood Eosinophil Count are Risk Factors for Hospital Readmission and Mortality in Patients with COPD

Introduction

The biomarker soluble urokinase plasminogen activator receptor (suPAR) has been associated with increased mortality in chronic obstructive pulmonary disease (COPD), while elevated blood eosinophils have been associated with better survival. We hypothesized that suPAR and blood eosinophil count are independent risk factors for readmission and mortality after an acute admission in patients with COPD.

Methods

This retrospective cohort study comprised 4022 patients with prevalent COPD acutely admitted to Hvidovre Hospital, Denmark. Irrespective of cause of admission, suPAR and blood eosinophils were measured, and patients were followed up to 365 days. Associations with 365-day respiratory readmission, all-cause readmission and all-cause mortality were investigated by Cox regression analyses adjusted for age, sex, Charlson score and C-reactive protein.

Results

suPAR was significantly elevated in patients who later experienced readmission or died. At 365 days, hazard ratios (HRs) for all-cause readmission and mortality reached 1.61 (95% CI 1.40–1.85; p<0.0001) and 3.40 (95% CI 2.64–4.39; p<0.0001), respectively, for COPD patients in the fourth suPAR quartile compared to patients in the first suPAR quartile. High blood eosinophils (>300 cells/μL) were associated with lower risk of mortality (HR 0.49, 95% CI 0.39–0.62; p<0.0001) compared with patients with <150 cells/μL. When stratifying patients by suPAR quartiles and blood eosinophil counts, the highest relative mortality rate was found in patients belonging to both the fourth suPAR quartile and the low blood eosinophil (<150 cells/μL) group.

Conclusion

In this cohort of COPD patients acutely admitted to a hospital, elevated suPAR concentrations were associated with both higher risk of all-cause readmission and mortality, whereas higher blood eosinophil count was associated with lower risk of mortality.

Fractional Exhaled Nitric Oxide is Associated with the Severity of Stable COPD

The value of fractional exhaled nitric oxide (FeNO) in patients with chronic obstructive pulmonary disease (COPD) remains unclear. We aimed to assess whether FeNO is a more valuable biomarker than blood eosinophil count for identifying clinical characteristics of COPD. Stable COPD patients (n = 390) were included and stratified by FeNO and blood eosinophil counts at recruitment. The demographic characteristics, lung functions, St George Respiratory Questionnaire (SGRQ), serum inhaled allergen-specific IgE and the exacerbations in the preceding 12 months were compared. Risk factors for moderate or severe exacerbation in the preceding 12 months were examined by binary regression analysis. The cross-sectional study showed that 167 patients had high level of FeNO (≥25 ppb) and 223 in low level (<25 ppb), while 138 patients had high blood eosinophil count (≥200 cells/μL) and 252 had low (<200 cells/μL). Compared with the high FeNO group, there were higher proportion of patients with GOLD III-IV, higher SGRQ scores, more exacerbations in the preceding 12 months, and with lower positive proportion of sIgE in the low FeNO group (p < 0.05 for all). However, these phenomena above were not associated with blood eosinophil count. Finally, high FeNO level was associated with a lower moderate or severe exacerbation in preceding 12 months (RR: 0.541 [95%CI 0.319-0.917], p = 0.023). In stable COPD patients, FeNO, but not blood eosinophil count was associated with the COPD severity and allergic airway inflammation. However, the role of FeNO in guiding personalized treatment of COPD patients need to be further investigated.

Blood Eosinophil Counts and Their Variability and Risk of Exacerbations in COPD: A Population-Based Study

BACKGROUND

There is controversy regarding the role of blood eosinophil levels as a biomarker of exacerbation risk in chronic obstructive pulmonary disease (COPD). Our aim was to quantify blood eosinophil levels and determine the risk of exacerbations associated with these levels and their variability.

METHODS

Observational, retrospective, population-based study with longitudinal follow-up in patients with COPD identified in a primary care electronic medical record database in Catalonia, Spain, covering 80% of the general population. Patients were classified into 4 groups using the following cut-offs: (a) <150cells/μl; (b) ≥150 and <300cells/μl; (c) ≥300 and <500cells/μl; (d) ≥500cells/μl.

RESULTS

A total of 57,209 patients were identified with a mean age of 70.2 years, a mean FEV1(% predicted) of 64.1% and 51.6% had at least one exacerbation the previous year. The number of exacerbations in the previous year was higher in patients with the lowest and the highest eosinophil levels compared with the intermediate groups. During follow-up the number of exacerbations was slightly higher in the group with the lowest blood eosinophil levels and in those with higher variability in eosinophil counts, but ROC curves did not identify a reliable threshold of blood eosinophilia to discriminate an increased risk of exacerbations.

CONCLUSIONS

Our results do not support the use of blood eosinophil count as a reliable biomarker of the risk of exacerbation in COPD in a predominantly non-exacerbating population. Of note was that the small group of patients with the highest variability in blood eosinophils more frequently presented exacerbations.

Point of Care Portable Spirometry in the Diagnosis and Treatment of Inpatients with Chronic Obstructive Pulmonary Disease

INTRODUCTION

Spirometry is required to accurately diagnose chronic obstructive pulmonary disease (COPD). Following an acute exacerbation, it is recommended that spirometry be performed after a delay of 4-6 weeks to allow stability and a measure of 'baseline' lung function. However, poor attendance at these appointments can occur, leading to an inability to confirm the diagnosis of COPD or assess the severity of airflow obstruction. Portable spirometry (PS) is a proven surrogate device that may provide a convenient method to address these issues. The purpose of this study was to compare PS values, obtained prior to hospital discharge to laboratory-based spirometry (LS) results undertaken 4 weeks later.

METHODS

Thirty-three eligible inpatients with a clinically determined exacerbation of COPD were recruited. Patients underwent PS prior to discharge and LS 4 weeks later.

RESULTS

Reliability of PS values at discharge compared with outpatient LS 4 weeks later was excellent (intraclass correlation coefficient > 0.9). The PS confirmed a new diagnosis of COPD at the bedside in 29% of patients and excluded COPD in 6% at both time points. Patients were found to have a similar severity of airflow obstruction on both PS and LS, with clinical stability maintained between visits. The PS and LS may be used interchangeably for earlier diagnosis of COPD. PS at the point of discharge from hospital offers a unique opportunity to diagnose and facilitate COPD management from hospital to primary care.

Clinical Characteristics and Risk of Exacerbations Associated With Different Diagnostic Criteria of Asthma-COPD Overlap

INTRODUCTION

There is currently no universally accepted definition of asthma-COPD overlap (ACO).

OBJECTIVE

To compare the prevalence of ACO in patients with asthma or COPD, and to assess their clinical characteristics and the capacity of the different definitions to predict the risk of exacerbation.

METHOD

Prospective observational study with a 12-month follow-up in an asthma cohort and a COPD cohort. Four diagnostic criteria were compared: A) the Spanish 2012 consensus; B) the 2016 international consensus; C) the 2017 consensus between the Spanish COPD guidelines (GesEPOC) and GEMA asthma guidelines; and D) the single criterion of ≥300eosinophils/μL, proposed by GOLD 2019. The risk of exacerbations was evaluated in each group.

RESULTS

A total of 345 patients were included, 233 (67.5%) with COPD and 112 (32.5%) with asthma, aged 63±14 years, 70.4% men. Fifteen (4.3%) patients met the criteria for ACO according to the criteria described under A above; 30 (8.7%) with the criteria of B; 118 (34.2%) with the criteria of C; and 97 (28.1%), with the D criterion. The ACO-COPD subtype were older, had worse lung function, and an increased risk of exacerbation compared with the ACO-asthma group. Of all the definitions evaluated, those which distinguished a higher risk of exacerbations were the GesEPOC-GEMA consensus and the GOLD proposal.

CONCLUSIONS

The prevalence of ACO varies enormously depending on the diagnostic criteria used. The ACO population is heterogeneous, and the ACO-COPD subtype is very different from the ACO-asthma subtype. The definitions that include eosinophilia identify ACO patients with a greater risk of exacerbation.

COPD: To Be or Not to Be, That is the Question

As our knowledge on the natural history of chronic obstructive pulmonary disease (COPD) progresses, a conceptual model simply based on an accelerated decline of lung function in adult life in response to smoking has become inadequate to capture the complexity of this disease, and increasing attention is being given to possible contributions from events or alterations of developmental processes that take place earlier in life. In addition, a remarkable heterogeneity has emerged among the pathobiological mechanisms that are involved in different phenotypes of COPD, suggesting that an effective disease management will require individualized treatment approaches largely based on the underlying biological mechanisms (endotypes). In this review, we will discuss the many faces of COPD from an epidemiological, pathobiological, and clinical standpoint and argue that airflow limitation encompasses a number of manifestations that are too diverse to be still clustered under the same diagnostic label.

Relationship between Blood and Induced Sputum Eosinophils, Bronchial Hyperresponsiveness and Reversibility of Airway Obstruction in Mild-to-Moderate Chronic Obstructive Pulmonary Disease

Blood eosinophilia has been proposed as a surrogate marker for airway eosinophilia and as a predictor of treatment response in chronic obstructive pulmonary disease (COPD). The aim of the study was to assess the relationship between blood and sputum eosinophils and to investigate the association between blood and sputum eosinophil count and clinical features of mild-to-moderate COPD. We performed a retrospective analysis of blood and sputum eosinophil count, as well as demographic and lung function data in a cohort of 90 stable, steroid-naive (Global Initiative for Chronic Obstructive Lung Disease 1 or 2) COPD patients and 20 control subjects. Blood and sputum eosinophil count did not correlate both in patients with COPD (r = -0.04 p = 0.705) and in controls (r = 0.05, p = 0.838). Sputum eosinophilia (≥3%) was present in 40% of COPD patients. The median blood eosinophil count in patients with COPD was 180 (interquartile range 90-270)/μL; patients with low blood eosinophils (<180/μL) did not differ from those with high blood eosinophils (≥180/μL) in terms of forced expiratory volume in 1 second, bronchial reversibility or hyperresponsiveness. This was also the case when COPD patients with and without sputum eosinophilia were compared. At the same time, positive bronchial reversibility and positive bronchial hyperresponsiveness were observed in 2 (11%) COPD patients with high blood eosinophils and in 1 (5%) patient with sputum eosinophilia. There was a weak, albeit significant correlation (r = 0.22 p = 0.041) between blood eosinophil count and age in patients with COPD. Peripheral eosinophil count poorly reflects sputum eosinophils and lung function in stable steroid-naive mild-to-moderate COPD patients.

[Eosinophilic inflammation in chronic obstructive pulmonary disease]

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that combines various clinical manifestations and pathophysiological mechanisms. It underlies the separation of patients with COPD by phenotypes, endotypes and a personalized therapy of this disease. The implementation of this approach is possible only with the use of appropriate biomarkers. One of the most important biomarkers of COPD is eosinophilia of blood and/or sputum, which is considered as a predictor of frequent exacerbations and the effectiveness of inhaled glucocorticosteroids in patients with COPD. The literature discusses the impact of eosinophilic inflammation on the prognosis, clinical and functional parameters in COPD, and the role of the targeted therapy in the treatment of eosinophilic COPD.

Blood eosinophils could be useful as a biomarker in chronic obstructive pulmonary disease exacerbations

Introduction The aim of analysing the usefulness of the blood eosinophil count (BEC) as a prognostic marker in exacerbations of patients with Chronic Obstructive Pulmonary Disease (COPD), evaluating its relationship with hospital mortality, the length of stay and the early and late re-admissions. Materials and Methods We have carried out a retrospective study including all patients who required hospital admission from 1 January 2008 to 31 December 2009, with a diagnosis on hospital discharge of COPD exacerbation. These patients were classified using three cut-off points of BEC: less than 200 vs ≥ 200/µL, less than 300 vs ≥ 300/µL and less than 400 vs ≥ 400/µL. Results There were a total of 1626 hospital admissions during the study period with the diagnosis of exacerbation of COPD. In this study we have included 358 patients. The probability of any late re-admission increased with a BEC ≥ 300/µL (odds ratio: 1.684) and for those with a BEC ≥ 400/µL (odds ratio: 2.068). The BEC does not appear to be related to hospital mortality or the probability of early re-admission after an exacerbation of COPD. Conclusions In our study an elevated BEC is associated with a higher incidence of late hospital readmissions in COPD exacerbations.

The association between airflow limitation and blood eosinophil levels with treatment outcomes in patients with chronic obstructive pulmonary disease and prolonged mechanical ventilation

The clinical implications of airflow limitation severity and blood eosinophil level in patients with chronic obstructive pulmonary disease (COPD) and prolonged mechanical ventilation (PMV) are unknown. Thus, this study aimed to identify whether or not these two indicators were significantly associated with short-term in-respiratory care center (RCC) treatment outcomes in this population. Of all participants (n = 181) in this retrospective cross-sectional study, 41.4%, 40.9%, 8.3%, and 52.5% had prolonged RCC admission (RCC length of stay >21 days), failed weaning, death, and any adverse outcomes of interest, respectively. Compared to participants without any adverse outcomes of interest, moderate (the Global Initiative for Chronic Obstructive Lung Disease (GOLD) II) and/or severe (GOLD III) airflow limitation were significantly associated with short-term in-RCC adverse outcomes in terms of failed weaning (for III versus I, OR = 15.06, p = 0.003) and having any adverse outcomes of interest (for II versus I, OR = 17.66, p = 0.002; for III versus I, OR = 37.07, p = 0.000) though the severity of airflow limitation did not have associations with prolonged RCC admission and death after adjustment. Meanwhile, blood eosinophilia defined by various cut-off values was not associated with any adverse outcomes. The findings have significant clinical implications and are useful in the management of patients with COPD and PMV.

Clinical and Functional Characteristics of COPD Patients Across GOLD Classifications: Results of a Multicenter Observational Study

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. The severity grading systems proposed by the Global initiative for Chronic Obstructive Lung Disease (GOLD) have changed over time. The aim of the study was to evaluate if the different GOLD classifications can capture the complexity of the disease by investigating the distribution of lung function and clinical parameters across the GOLD classification systems. This was an observational, retrospective, multicentre study. COPD patients were stratified according to the GOLD severity grading proposed in the 2007, and to the ABCD assessment tool present in the 2011, and 2017 versions of the initiative. Data from body plethysmography, DLCO, comorbidities, exacerbation history, pharmacological therapy and eosinophil counts were collected. A total of 1360 patients (73.4% males) were included in the analysis. Overall, 37% of the patients were severe-very severe according to GOLD 2007. Compared with GOLD 2011, applying the GOLD 2017 criteria, the proportion of the at risk categories (C and D) was reduced by ∼23%. Impairment in inspiratory capacity, DLCO and the prevalence of emphysema paralleled the GOLD 2007 classification only. The proportion of patients with ≥ 200 eosinophils/µL was higher in GOLD 2007 stages 3-4 compared with stages 1-2 (P = 0.008). Eosinophil levels were similar across risk classes in GOLD 2011 and 2017. Overall, 41.8% and 52.4% of the patients in the low risk groups according to GOLD 2011 and 2017 were exposed to inhaled corticosteroids. The GOLD 2011 and 2017 classifications, despite exploring symptoms and exacerbations, might miss other relevant patients' clinical characteristics such as lung function and phenotypes, which have a significant impact on outcomes and disease severity.

Reassessing the Role of Eosinophils as a Biomarker in Chronic Obstructive Pulmonary Disease

Blood eosinophils measurement, as proxy for tissue eosinophils, has become an important biomarker for exacerbation risk and response to inhaled corticosteroids (ICS) in Chronic Obstructive Pulmonary Disease (COPD). Its use to determine the pharmacological approach is recommended in the latest COPD guidelines. The potential role of blood eosinophils is mainly based on data derived from post-hoc and retrospective analyses that showed an association between increased blood eosinophils and risk of exacerbations, as well as mitigation of this risk with ICS. Yet other publications, including studies in real life COPD, do not confirm these assumptions. Moreover, anti-eosinophil therapy targeting interleukin (IL)-5 failed to reduce exacerbations in COPD patients with high blood eosinophils, which casts significant doubts on the role of eosinophils in COPD. Furthermore, a reduction of eosinophils might be harmful since COPD patients with relatively high eosinophils have better pulmonary function, better life quality, less infections and longer survival. These effects are probably linked to the role of eosinophils in the immune response against pathogens. In conclusion, in COPD, high blood eosinophils are widely used as a biomarker for exacerbation risk and response to ICS. However, much is yet to be learned about the reasons for the high eosinophil counts, their variations and their controversial effects on the fate of COPD patients.

Inflammatory endotypes in COPD

Chronic obstructive pulmonary disease (COPD) is a major global health problem that is poorly treated by current therapies as it has proved difficult to treat the underlying inflammation, which is largely corticosteroid-resistant in most patients. Although rare genetic endotypes of COPD have been recognized, despite the clinical heterogeneity of COPD, it has proved difficult to identify distinct inflammatory endotypes. Most patients have increased neutrophils and macrophages in sputum, reflecting the increased secretion of neutrophil and monocyte chemotactic mediators in the lungs. However, some patients also have increased eosinophils in sputum and this may be reflected by increased blood eosinophils. Increased blood and sputum eosinophils are associated with more frequent exacerbations and predict a good response to corticosteroids in reducing and treating acute exacerbations. Eosinophilic COPD may represent an overlap with asthma but the mechanism of eosinophilia is uncertain as, although an increase in sputum IL-5 has been detected, anti-IL-5 therapies are not effective in preventing exacerbations. More research is needed to link inflammatory endotypes to clinical manifestations and outcomes in COPD and in particular to predict response to precision medicines.

Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease: the GOLD science committee report 2019

Precision medicine is a patient-specific approach that integrates all relevant clinical, genetic and biological information in order to optimise the therapeutic benefit relative to the possibility of side-effects for each individual. Recent clinical trials have shown that higher blood eosinophil counts are associated with a greater efficacy of inhaled corticosteroids (ICSs) in chronic obstructive pulmonary disease (COPD) patients. Blood eosinophil counts are a biomarker with potential to be used in clinical practice, to help target ICS treatment with more precision in COPD patients with a history of exacerbations despite appropriate bronchodilator treatment.The Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2017 pharmacological treatment algorithms, based on the ABCD assessment, can be applied relatively easily to treatment-naive individuals at initial presentation. However, their use is more problematic during follow-up in patients who are already on maintenance treatment. There is a need for a different system to guide COPD pharmacological management during follow-up.Recent large randomised controlled trials have provided important new information concerning the therapeutic effects of ICSs and long-acting bronchodilators on exacerbations. The new evidence regarding blood eosinophils and inhaled treatments, and the need to distinguish between initial and follow-up pharmacological management, led to changes in the GOLD pharmacological treatment recommendations. This article explains the evidence and rationale for the GOLD 2019 pharmacological treatment recommendations.

New frontiers in the treatment of comorbid cardiovascular disease in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a disease characterised by persistent airflow limitation that is not fully reversible and is currently the fourth leading cause of death globally. It is now well established that cardiovascular-related comorbidities contribute to morbidity and mortality in COPD, with approximately 50% of deaths in COPD patients attributed to a cardiovascular event (e.g. myocardial infarction). Cardiovascular disease (CVD) and COPD share various risk factors including hypertension, sedentarism, smoking and poor diet but the underlying mechanisms have not been fully established. However, there is emerging and compelling experimental and clinical evidence to show that increased oxidative stress causes pulmonary inflammation and that the spill over of pro-inflammatory mediators from the lungs into the systemic circulation drives a persistent systemic inflammatory response that alters blood vessel structure, through vascular remodelling and arterial stiffness resulting in atherosclerosis. In addition, regulation of endothelial-derived vasoactive substances (e.g. nitric oxide (NO)), which control blood vessel tone are altered by oxidative damage of vascular endothelial cells, thus promoting vascular dysfunction, a key driver of CVD. In this review, the detrimental role of oxidative stress in COPD and comorbid CVD are discussed and we propose that targeting oxidant-dependent mechanisms represents a novel strategy in the treatment of COPD-associated CVD.

Exacerbations and health care resource use among patients with COPD in relation to blood eosinophil counts

Purpose

Current understanding of the relationship between COPD phenotype and health care resource utilization (HCRU) is limited. This real-world study evaluated disease burden and HCRU for COPD subgroups prone to exacerbation as defined by blood eosinophil (EOS) count and multiple inhaler triple therapy (MITT) use.

Methods

This was a large-scale, retrospective, longitudinal, observational cohort study using data from the US IBM Watson Explorys real-world database (GSK Study HO-17-18395). The population of interest comprised patients with COPD ≥40 years of age with ≥2 moderate or ≥1 severe exacerbations (prior year) while on inhaled maintenance therapy, with ≥1 blood EOS count. Data were analyzed during the year prior to index date (last COPD encounter between January 1, 2011 and December 31, 2016). Four subgroups were analyzed based on a combination of EOS counts (<150 and ≥150 cells/μL) and MITT use (receiving or not receiving). Among these groups, clinical characteristics, exacerbations, and HCRU were described. A sensitivity analysis that further stratified EOS into four categories (<150, ≥150–<300, ≥300–<500, and ≥500 cells/μL) was also performed.

Results

The COPD population of interest comprised 34,268 patients. Subgroups with EOS ≥150 cells/μL vs <150 cells/μL had more comorbidities and experienced significantly higher mean numbers of moderate exacerbations (not receiving MITT, ≥150 cells/μL vs <150 cells/μL: 1.93 vs 1.82, P<0.0001; receiving MITT 2.26 vs 2.16, P=0.0062) and COPD-related emergency visits (not receiving MITT, ≥150 cells/μL vs <150 cells/μL: 3.0 vs 2.5, P<0.001; receiving MITT 3.4 vs 3.1, P=0.0011). Increasing EOS category was associated with higher HCRU.

Conclusion

Blood EOS ≥150/μL cells were associated with increased HCRU and higher exacerbation rates compared with EOS <150 cells/μL, irrespective of MITT use. COPD phenotyping using blood EOS could help identify candidates for additional therapies that target eosinophilic inflammatory pathways.

ACO: Time to move from the description of different phenotypes to the treatable traits

Background

Asthma-COPD overlap (ACO) is a term that encompasses patients with characteristics of two conditions, smoking asthmatics or COPD patients with asthma-like features such as high bronchodilator response or blood eosinophil count ≥300 cells/μL. The aim of this study was to compare the different phenotypes inside the ACO definition in a real-life population cohort.

Methods

We analyzed patients from the MAJORICA cohort who had a diagnosis of asthma and/or COPD based on current guidelines, laboratory data in 2014 and follow-up until 2015. Prevalence of ACO according to the different criteria, demographic, clinical and functional characteristics, prescriptions and use of health resources data were compared between three groups.

Results

We included 603 patients. Prevalence of smoking asthmatics was 14%, COPD patients with high bronchodilator response 1.5% and eosinophilic COPD patients 12%. Smoking asthmatics were younger and used more rescue inhalers, corticosteroids and health resources. Conversely, eosinophilic COPD patients were older than the other groups, often treated with corticosteroids and had lower use of health resources. Most of the COPD patients with high bronchodilator response were included in the eosinophilic COPD group.

Conclusions

ACO includes two conditions (smoking asthmatics and eosinophilic COPD patients) with different medication requirement and prognosis that should not be pooled together. Use of ≥300 blood eosinophils/μL as a treatable trait should be recommended.

Phenotyping patients with chronic cough: Evaluating the ability to predict the response to anti-inflammatory therapy

BACKGROUND

Whether the fraction of exhaled nitric oxide (FeNO) measurement can predict the response to anti-inflammatory treatment in chronic cough is unknown.

OBJECTIVE

To explore whether the effectiveness of treatment with 10 mg of montelukast or 20 mg of prednisolone in patients with chronic cough is predicted by FeNO level.

METHODS

In this randomized, open-label, controlled pilot study conducted in the Clinical Trial Unit in Castle Hospital in the United Kingdom, 50 nonsmoking patients with a cough that lasted more than 8 weeks were sequentially enrolled in the study. Thirty patients with high FeNO levels (≥30 ppb) were randomized in a 1:1 ratio to receive 10 mg of montelukast or 20 mg of prednisolone for 2 weeks followed by 10 mg of montelukast for 2 weeks. Twenty patients with a low FeNO level (≤20 ppb) received 10 mg of montelukast. The primary objective was to determine the effectiveness of treatment on 24-hour cough counts.

RESULTS

The 24-hour cough counts decreased in both groups by approximately 50% (P < .005), indicating that FeNO did not predict treatment response. However, it was a good marker for eosinophilic inflammation with a high degree of correlation with blood and sputum eosinophilia (P < .001).

CONCLUSION

These results suggest that prior investigation may not predict response to anti-inflammatory treatment, which may be consequent on localized leukotriene-mediated inflammation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02479074.

Blood eosinophil count as a prognostic biomarker in COPD

Background

High blood eosinophil count is a predictive biomarker for response to inhaled corticosteroids in prevention of acute exacerbation of COPD, and low blood eosinophil count is associated with pneumonia risk in COPD patients taking inhaled corticosteroids. However, the prognostic role of blood eosinophil count remains underexplored. Therefore, we investigated the associated factors and mortality based on blood eosinophil count in COPD.

Methods

Patients with COPD were recruited from 16 hospitals of the Korean Obstructive Lung Disease cohort (n=395) and COPD in Dusty Area cohort (n=234) of Kangwon University Hospital. The two merged cohorts were divided based on blood eosinophil count into three groups: high (≥5%), middle (2%-5%), and low (<2%).

Results

The high group had longer six-minute walk distance (high =445.8±81.4, middle =428.5±88.0, and low =414.7±86.3 m), higher body mass index (23.3±3.1, 23.1±3.1, and 22.5±3.2 kg/m²), lower emphysema index (18.5±14.1, 22.2±15.3, and 23.7±16.3), and higher inspiratory capacity/total lung capacity ratio (32.6±7.4, 32.4±9.2, and 29.9% ± 8.9%) (P<0.05). The survival period increased with increasing blood eosinophil count (high =9.52±0.23, middle =8.47±1.94, and low =7.42±0.27 years, P<0.05). Multivariate linear regression analysis revealed that the emphysema index was independently and negatively correlated with blood eosinophil count (P<0.05).

Conclusion

In COPD, the severity of emphysema was independently linked with low blood eosinophil count and the longer survival period was associated with increased blood eosinophil count, though it was not proven in the multivariate analysis.

Precision medicine in COPD: where are we and where do we need to go?

Chronic obstructive pulmonary disease (COPD) was the fourth leading cause of death worldwide in 2015. Current treatments for patients ease discomfort and help decrease disease progression; however, none improve lung function or change mortality. COPD is heterogeneous in its molecular and clinical presentation, making it difficult to understand disease aetiology and define robust therapeutic strategies. Given the complexity of the disease we propose a precision medicine approach to understanding and better treating COPD. It is possible that multiOMICs can be used as a tool to integrate data from multiple fields. Moreover, analysis of electronic medical records could aid in the treatment of patients and in the predictions of outcomes. The Precision Medicine Initiative created in 2015 has made precision medicine approaches to treat disease a reality; one of these diseases being COPD.

Clinical features, bacteriology of endotracheal aspirates and treatment outcomes of patients with chronic obstructive pulmonary disease and community-acquired pneumonia in an intensive care unit in Taiwan with an emphasis on eosinophilia versus non-eosinophilia: a retrospective case-control study

OBJECTIVES

The clinical implications of blood eosinophil level in patients with chronic obstructive pulmonary disease (COPD) and community-acquired pneumonia (CAP) requiring invasive mechanical ventilation (IMV) and intensive care unit (ICU) admission are still unknown. Thus, this study aimed to compare the features of such patients with and without blood eosinophilia.

DESIGN

This was a retrospective case-control study.

SETTING

An ICU of a medical centre in central Taiwan.

PARTICIPANTS

A total of 262 patients with COPD and CAP requiring IMV and ICU admission.

RESULTS

Of all participants (n=262), 32 (12.2%) had an eosinophil percentage (EP) >2% and 169 (64.5%) had an absolute eosinophil count (AEC) >300 cells/µL. Regardless of whether 2% or 300 cells/µL was used as a cut-off value, the eosinophilia group were slightly older (years) (82.9±5.4 vs 78.1±9.1, p=0.000 and 79.2±8.4 vs 77.6±9.6, p=0.246, respectively), and had a higher forced expiratory volume in 1 s/forced vital capacity (%) (56.0±8.0 vs 51.3±11.6, p=0.005 and 53.1±11.2 vs 49.5±11.2, p=0.013, respectively), less severe spirometric classification (p=0.008 and p=0.001, respectively), and lower white cell count 109/L (8.8±3.2 vs 11.1±4.9, p=0.009 and 10.3±4.4 vs 11.8±5.3, p=0.017, respectively) than the non-eosinophilia group. The bacteriology of endotracheal aspirates showed that Pseudomonas aeruginosa and other gram-negative bacilli were the most common organisms in all study groups. Participants with an EP >2% had a shorter ICU length of stay (OR=12.13, p=0.001) than those with an EP ≤2%, while an AEC >300 cells/µL was not associated with any in-ICUoutcomes.

CONCLUSIONS

The results of this study have significant clinical implications and should be considered when making treatment decisions for the management of patients with COPD and CAP requiring IMV and ICU admission.

Circulating eosinophil levels do not predict severe exacerbations in COPD: a retrospective study

Whether the level of circulating eosinophils in chronic obstructive pulmonary disease (COPD) patients can predict the risk of exacerbations of COPD (ECOPD) or response to treatment is debated. Here, we evaluate the prevalence of elevated eosinophils in COPD patients and its relationship with severe ECOPD requiring hospitalisation. We retrospectively reviewed the charts of COPD patients hospitalised in our centre between January 1, 2005 and November 30, 2015 because of ECOPD or other reasons (controls). In a second analysis, the ECOPD patients were divided into two subgroups based on having ECOPD in the next year after the index event or not. Circulating eosinophils, both during clinical stability and hospitalisation, as well as clinical and functional data and the relation to recurrent exacerbations were analysed. We studied 992 COPD patients (318 ECOPD patients and 674 controls). Among ECOPD patients, 121 had one or more ECOPD during the year after the index event. The prevalence of eosinophils ≥2% was 72% in ECOPD patients and 71% in controls (p=0.93). Among ECOPD patients, eosinophil levels ≥2%, ≥4% or ≥300 cells·μL^-1, either when clinically stable or during hospitalisation, did not show a significant association with the rate of recurrent severe exacerbations. The severity of airflow limitation was associated with recurrent exacerbations, but inhaled corticosteroid treatment was not. The majority of COPD patients have circulating eosinophils >2% and a significant association with the risk of severe ECOPD or response to inhaled corticosteroids was not demonstrated.

Serial blood eosinophils and clinical outcome in patients with chronic obstructive pulmonary disease

BACKGROUND

Blood eosinophils have been suggested as a potential biomarker in chronic obstructive pulmonary disease (COPD), and their stability over time has been investigated in a few studies. However, the association between the stability of blood eosinophils and long-term clinical outcomes in COPD patients has yet to be fully elucidated. This study aimed to evaluate the stability of blood eosinophils and its association with clinical outcomes in COPD patients.

METHODS

In total, 299 COPD patients from the Korean Obstructive Lung Disease cohort with at least two blood eosinophil measurements were included. Patients were stratified according to a cut-off of 300 cells/μL, and the association between eosinophil changes and all-cause mortality was analysed. The annual decline in forced expiratory volume in 1 s (FEV1), serial changes in St George's Respiratory Questionnaire score (SGRQ), and exacerbations during follow-up were compared among eosinophil groups.

RESULTS

Patients were stratified into three groups according to the blood eosinophil cut-off: persistently < 300 cells/μL (PL; n = 175), variable (V; n = 68), and persistently ≥300 cells/μL (PH; n = 56). There were no significant differences in baseline characteristics (age, sex, smoking, body mass index, use of inhaled corticosteroids, exacerbations in the previous year, FEV1 (L or % predicted), or emphysema score) among the groups. During a median follow-up of 6.0 years, the PH group had a better survival rate than the PL group (adjusted mortality rate ratio, 0.29; 95% confidence interval, 0.09-0.97; P = 0.045). The PH group also showed improved symptoms and impact domains of SGRQ score compared to the PL group. No difference was found in annual FEV1 decline or exacerbations during follow-up among the groups.

CONCLUSIONS

Patients with persistently high blood eosinophils had a better survival rate than those with persistently low blood eosinophils. Serial follow-up of blood eosinophils could help to predict outcomes in COPD patients.

Blood eosinophil count thresholds and exacerbations in patients with chronic obstructive pulmonary disease

BACKGROUND

Eosinophilic airway inflammation in patients with chronic obstructive pulmonary disease (COPD) is associated with exacerbations and responsivity to steroids, suggesting potential shared mechanisms with eosinophilic asthma. However, there is no consistent blood eosinophil count that has been used to define the increased exacerbation risk.

OBJECTIVE

We sought to investigate blood eosinophil counts associated with exacerbation risk in patients with COPD.

METHODS

Blood eosinophil counts and exacerbation risk were analyzed in patients with moderate-to-severe COPD by using 2 independent studies of former and current smokers with longitudinal data. The Genetic Epidemiology of COPD (COPDGene) study was analyzed for discovery (n = 1,553), and the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study was analyzed for validation (n = 1,895). A subset of the ECLIPSE study subjects were used to assess the stability of blood eosinophil counts over time.

RESULTS

COPD exacerbation risk increased with higher eosinophil counts. An eosinophil count threshold of 300 cells/μL or greater showed adjusted incidence rate ratios for exacerbations of 1.32 in the COPDGene study (95% CI, 1.10-1.63). The cutoff of 300 cells/μL or greater was validated for prospective risk of exacerbation in the ECLIPSE study, with adjusted incidence rate ratios of 1.22 (95% CI, 1.06-1.41) using 3-year follow-up data. Stratified analysis confirmed that the increased exacerbation risk associated with an eosinophil count of 300 cells/μL or greater was driven by subjects with a history of frequent exacerbations in both the COPDGene and ECLIPSE studies.

CONCLUSIONS

Patients with moderate-to-severe COPD and blood eosinophil counts of 300 cells/μL or greater had an increased risk exacerbations in the COPDGene study, which was prospectively validated in the ECLIPSE study.

Blood eosinophil count and risk of pneumonia hospitalisations in individuals with COPD

Blood eosinophil count in chronic obstructive pulmonary disease (COPD) is associated with higher exacerbation rate and favourable response to corticosteroids; however, frequent exacerbations and use of inhaled corticosteroids could elevate pneumonia risk. We tested the hypothesis that high blood eosinophil counts are associated with high risk of pneumonia in individuals with severe COPD from the general population.

We included 7180 individuals with COPD from the Copenhagen General Population Study, including 643 with forced expiratory volume in 1 s (FEV1) <50% predicted between 2003 and 2011. All primary discharge diagnoses of pneumonia during follow-up were recorded.

Among individuals with COPD and FEV1<50% pred, the multivariable adjusted incidence rate ratio was 2.17 (95% CI 1.31–3.58) for pneumonia comparing individuals with blood eosinophil counts ≥0.34×109 cells·L−1versus<0.34×109 cells·L−1. In individuals with clinical COPD, defined by recent exacerbation, ≥10 pack-years of smoking and FEV1<70% pred, the corresponding risk was 4.52 (2.11–9.72). Risk of pneumonia did not differ by blood eosinophil count in individuals with COPD and FEV1≥50% pred.

In individuals with COPD and FEV1<50% pred, blood eosinophil count ≥0.34×109 cells·L−1was associated with high risk of hospitalisation due to pneumonia.