Cardiovascular morbidity in COPD: A study of the general population

Unlocking the link: predicting cardiovascular disease risk with a focus on airflow obstruction using machine learning

BACKGROUND

Respiratory diseases and Cardiovascular Diseases (CVD) often coexist, with airflow obstruction (AO) severity closely linked to CVD incidence and mortality. As both conditions rise, early identification and intervention in risk populations are crucial. However, current CVD risk models inadequately consider AO as an independent risk factor. Therefore, developing an accurate risk prediction model can help identify and intervene early.

METHODS

This study used the National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and NHANES 2007-2012 datasets. Inclusion criteria were participants aged over 40 with complete AO and CVD data; exclusions were those with missing key data. Analysis included 12 variables: age, gender, race, PIR, education, smoking, alcohol, BMI, hyperlipidemia, hypertension, diabetes, and AO. Logistic regression analyzed the association between AO and CVD, with sensitivity and subgroup analyses. Six ML models predicted CVD risk for the general population, using AO as a predictor. RandomizedSearchCV with 5-fold cross-validation was used for hyperparameter optimization. Models were evaluated by AUC, accuracy, precision, recall, F1 score, and Brier score, with the SHapley Additive exPlanations (SHAP) enhancing explainability. A separate ML model was built for the subpopulation with AO, evaluated similarly.

RESULTS

The cross-sectional analysis showed that there was a significant positive correlation between AO occurrence and CVD prevalence, indicating that AO is an important risk factor for CVD (all P < 0.05). For the general population, the XGBoost model was selected as the optimal model for predicting CVD risk (AUC = 0.7508, AP = 0.3186). The top three features in terms of importance were age, hypertension, and PIR. For the subpopulation with airflow obstruction, the XGBoost model was also selected as the optimal model for predicting CVD risk (AUC = 0.6645, AP = 0.3545). SHAP shows that education level has the greatest impact on predicting CVD risk, followed by gender and race.

CONCLUSION

AO correlates positively with CVD. Age, hypertension, PIR affect CVD risk most in general. For AO patients, education, gender, ethnicity are key CVD risk factors.

Research Status and Direction of Chronic Obstructive Pulmonary Disease Complicated with Coronary Heart Disease: A Bibliometric Analysis from 2005 to 2024

Objective

There is increasing evidence that chronic obstructive pulmonary disease (COPD) is associated with coronary heart disease (CHD). In this study, we provide valuable insights in the field by examining the evolution of the relationship between COPD and CHD over the past 20 years.

Methods

A comprehensive computer search was conducted in the Web of Science (WOS) core dataset, covering literature on COPD combined with CHD from January 1, 2005, to August 20, 2024. Visual analyses were performed using VOSviewer, CiteSpace, and Bibliometrix to assess countries, institutions, the centrality of institutional intermediaries, authorship patterns, including co-cited authors and references, and keywords; Excel (version 2021) software was utilized for generating relevant descriptive analysis tables.

Results

A total of 2420 publications sourced from WOS were included in this study. Since 2005, there has been a continuous increase in the literature about COPD combined with CHD; polynomial fitting yielded an R² value of 0.7758. The volume of literature in this domain is projected to continue growing steadily. The United States emerged as the leading country by publication count; Lin Cheng-li ranked first among authors, while China Medical University topped institutional contributions. Notably, Sin dd, Mannino dm, and Helvaci Mr were identified as the top three authors based on citation frequency. The Journal of Vascular Surgery recorded the highest number of publications, whereas The Lancet was recognized as the most influential among the top ten co-cited journals. The most frequently cited reference pertains to systemic inflammation's role in increasing cardiovascular risk among patients with COPD. Through keyword clustering analysis, we categorized all keywords into three distinct groups: management strategies for COPD and CHD; diseases associated with both conditions; and epidemiological characteristics concerning their burden-current hotspots include multimorbidity factors such as hypertension and obesity alongside outcomes like diagnosis during COVID-19 pandemic implications within societal contexts are highlighted here too.

Conclusion

Presently focused research on COPD coupled with CHD primarily revolves around five key areas: pathogenesis exploration, early diagnostic techniques, COVID-19 infection, dynamics intervention, methodologies, and treatment protocol development efforts. To improve the early detection rate of COPD complicated with CHD, the main development direction in the future is to extract computed tomography (CT) features using imaging omics and establish an early prediction model. The results of this study will provide new ideas and directions for subsequent related research.

Contrasting effects of intracellular and extracellular human PCSK9 on inflammation, lipid alteration and cell death

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the major regulators of low-density lipoprotein receptor (LDLR). Information on role and regulation of PCSK9 in lung is very limited. Our study focuses on understanding the role and regulation of PCSK9 in the lung. PCSK9 levels are higher in Bronchoalveolar lavage fluid (BALF) of smokers with or without chronic obstructive pulmonary diseases (COPD) compared to BALF of nonsmokers. PCSK9-stimulated cells induce proinflammatory cytokines and activation of MAPKp38. PCSK9 transcripts are highly expressed in healthy individuals compared to COPD, pulmonary fibrosis or pulmonary systemic sclerosis. Cigarette smoke extract reduce PCSK9 levels in undifferentiated pulmonary bronchial epithelial cells (PBEC) but induce in differentiated PBEC. PCSK9 inhibition affect biological pathways, induces lipid peroxidation, and higher level of apoptosis in response to staurosporine. Our results suggest that higher levels of PCSK9 in BALF acts as an inflammatory marker. Furthermore, extracellular and intracellular PCSK9 play different roles.

Risk of Ischemic Heart Disease in Chronic Obstructive Pulmonary Disease: A Nationwide Cohort Study

BACKGROUND

Subjects with chronic obstructive pulmonary disease (COPD) have a higher risk of ischemic heart disease (IHD) than individuals without COPD; however, longitudinal evidence is lacking. Therefore, we aimed to estimate the risk of IHD between COPD and control cohorts using a longitudinal nationwide database.

METHODS

We used 2009-2017 data from the Korean National Health Insurance Service National Sample Cohort (NHIS-NSC). Adult participants at least 20 years of age who underwent health examinations and without a history of COPD or IHD were included (n = 540,976). Participants were followed from January 1, 2009, until death, development of IHD, or December 31, 2019, whichever came first.

RESULTS

At baseline, there were 3,421 participants with incident COPD and 537,555 participants without COPD. During a median of 8.0 years (5.3-9.1 years) of follow-up, 2.51% of the participants with COPD (n = 86) and 0.77% of the participants without COPD (n = 4,128) developed IHD, with an incidence of 52.24 and 10.91 per 10,000 person-years, respectively. Participants with COPD had a higher risk of IHD (adjusted hazard ratio, 1.55; 95% confidence interval, 1.25-1.93) than subjects without COPD. Demographics such as age, sex, body mass index, and personal health behaviors including smoking status and physical activity did not show significant interaction with the relationship between COPD and IHD (P for interaction > 0.05 for all).

CONCLUSION

The results indicate that COPD is associated with the development of IHD independent of demographic characteristics and health-related behaviors. Based on these results, clinicians should closely monitor the onset of IHD in subjects with COPD.

Factors associated with coronary heart disease in COPD patients and controls

Background

COPD and coronary heart disease (CHD) frequently co-occur, yet which COPD phenotypes are most prone to CHD is poorly understood. The aim of this study was to see whether COPD patients did have a true higher risk for CHD than subjects without COPD, and to examine a range of potential factors associated with CHD in COPD patients and controls.

Methods

347 COPD patients and 428 non-COPD controls, were invited for coronary computed tomography angiography (CCTA) and pulmonary CT. Arterial blood gas, bioelectrical impedance and lung function was measured, and a detailed medical history taken. The CCTA was evaluated for significant coronary stenosis and calcium score (CaSc), and emphysema defined as >10% of total area <-950 Hounsfield units.

Results

12.6% of the COPD patients and 5.7% of the controls had coronary stenosis (p<0.01), whereas 55.9% of the COPD patients had a CaSc>100 compared to 31.6% of the controls (p<0.01). In a multivariable model adjusting for sex, age, body composition, pack-years, CRP, cholesterol/blood pressure lowering medication use and diabetes mellitus, the OR (95% CI) for having significant stenosis was 1.80 (0.86–3.78) in COPD patients compared with controls. In a similar model, the OR (95% CI) for having CaSc>100 was 1.68 (1.12–2.53) in COPD patients compared with controls. Examining the risk of significant stenosis and CaSc>100 among COPD patients, no variable was associated with significant stenosis, whereas male sex [OR 2.85 (1.56–5.21)], age [OR 3.74 (2.42–5.77)], statin use [OR 2.23 (1.23–4.50)] were associated with CaSc>100, after adjusting for body composition, pack-years, C-reactive protein, use of angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), diabetes, emphysema score, GOLD category, exacerbation frequency, eosinophilia, and hypoxemia.

Conclusion

COPD patients were more likely to have CHD, but neither emphysema score, lung function, exacerbation frequency, nor hypoxemia predicted presence of either coronary stenosis or CaSc>100.

In Patients with Mild-to-Moderate COPD, Tobacco Smoking, and Not COPD, Is Associated with a Higher Risk of Cardiovascular Comorbidity

Background

Comorbidities including cardiovascular diseases are very common in chronic obstructive pulmonary disease (COPD) secondary to tobacco smoking and contribute to the overall severity of the disease. In non-smoking COPD, which accounts for about 25% of COPD cases worldwide, current knowledge on the frequency and determinants of comorbidities remains scarce. The aims of the current study were to assess the frequency of major comorbidities and to evaluate their determinants in a group of non-selected patients with mild-to-moderate COPD who were exposed to organic dust (dairy farmers), to tobacco smoking, or to both, and in controls without COPD who were exposed to organic dust (dairy farmers), or to tobacco smoking, or to both, or who were without exposure.

Patients and Methods

A total of 4665 subjects (2323 dairy farmers and 2342 non-farmers) including 355 patients with COPD and 4310 controls with normal spirometry were recruited through a large COPD screening program. Self-reported physician-diagnosed diseases with plausible links to COPD were recorded in this cross-sectional study.

Results

Whatever the exposure, cardiovascular comorbidities were not more frequent in patients with COPD than their counterparts without airflow limitation. A higher risk of major cardiovascular comorbidities was associated with tobacco smoking and a lower risk was associated with exposure to organic dusts.

Conclusion

Tobacco smoking (but not COPD) is associated with higher frequency of cardiovascular comorbidities. By contrast, being a dairy farmer exposed to organic dusts is associated with a lower frequency of the same comorbidities. This reinforces the crucial need for controlling established cardiovascular risk factors even in patients with mild-to-moderate COPD.

Cardiac biomarkers of prognostic importance in chronic obstructive pulmonary disease

Background

Ischemic heart disease is common in COPD and associated with worse prognosis. This study aimed to investigate the presence and prognostic impact of biomarkers of myocardial injury and ischemia among individuals with COPD and normal lung function, respectively.

Methods

In 2002–04, all individuals with airway obstruction (FEV₁/VC < 0.70, n = 993) were identified from population-based cohorts, together with age and sex-matched non-obstructive referents. At re-examination in 2005, spirometry, Minnesota-coded ECG and analyses of high-sensitivity cardiac troponin I (hs-cTnI) were performed in individuals with COPD (n = 601) and those with normal lung function (n = 755). Deaths were recorded until December 31st, 2010.

Results

Hs-cTnI concentrations were above the risk stratification threshold of ≥5 ng/L in 31.1 and 24.9% of those with COPD and normal lung function, respectively. Ischemic ECG abnormalities were present in 14.8 and 13.4%, while 7.7 and 6.6% had both elevated hs-cTnI concentrations and ischemic ECG abnormalities. The 5-year cumulative mortality was higher in those with COPD than those with normal lung function (13.6% vs. 7.7%, p < 0.001). Among individuals with COPD, elevated hs-cTnI both independently and in combination with ischemic ECG abnormalities were associated with an increased risk for death (adjusted hazard ratio [HR]; 95% confidence interval [CI] 2.72; 1.46–5.07 and 4.54; 2.25–9.13, respectively). Similar associations were observed also among individuals with COPD without reported ischemic heart disease.

Conclusions

In this study, elevated hs-cTnI concentrations in combination with myocardial ischemia on the electrocardiogram were associated with a more than four-fold increased risk for death in a population-based COPD-cohort, independent of disease severity.

Coronary heart disease and heart failure in asthma, COPD and asthma-COPD overlap

INTRODUCTION

We investigated risk of coronary heart disease and heart failure in phenotypes of obstructive airway disease.

METHODS

Among 91 692 participants in the Copenhagen General Population Study, 42 058 individuals were classified with no respiratory disease, and 11 988 individuals had different phenotypes of obstructive airways disease: asthma with early onset or late-onset, chronic obstructive pulmonary disease (COPD) with forced expiratory volume in one second (FEV₁) above or below 50% of predicted value (%p) or asthma-COPD overlap (ACO).

RESULTS

During a mean follow-up of 5.7 years we registered 3584 admissions for coronary heart disease and 1590 admissions for heart failure. Multivariable Cox regression analyses of time to first admission were used with a two-sided p value of 0.05 as significance level. Compared with no respiratory disease the highest risks of coronary heart disease and heart failure were observed in ACO with late-onset asthma and FEV₁ <50% p, HR=2.2 (95% CI 1.6 to 3.0), and HR=2.9 (95% CI 2.0 to 4.3), respectively. In COPD with FEV₁ above 50% p the HRs were 1.3 (95% CI 1.2 to 1.5) for coronary heart disease and 1.9 (95% CI 1.6 to 2.3) for heart failure. Asthma associated with increased risks of coronary heart disease and heart failure, however, in asthma without allergy the HR was 1.1 (95% CI 0.7 to 1.6) for coronary heart disease while individuals with allergy had an HR of 1.4 (95% CI 1.1 to 1.6).

CONCLUSIONS

Risks of coronary heart disease and heart failure were increased in asthma, COPD and ACO. In asthma, the risk of coronary heart disease depended on presence of allergy. We suggest that cardiovascular risk factors should be assessed systematically in individuals with obstructive airway disease with the potential to facilitate targeted treatments.

[Chronic obstructive pulmonary disease and cardiovascular comorbidity]

In recent years, a greater understanding of the heterogeneity and complexity of chronic obstructive pulmonary disease (COPD) has come from the point of view of an integrated clinical assessment of severity, pathophysiology, and the relationship with other pathologies. A typical COPD patient suffers on average 4 or more concomitant diseases and every day about a third of patients take from 5 to 10 different drugs. The mechanisms of the interaction of COPD and cardiovascular disease (CVD) include the effects of systemic inflammation, hyperinflation (hyperinflation) of the lungs and bronchial obstruction. The risk of developing CVD in patients with COPD is on average 2-3 times higher than in people of a comparable age in the general population, even taking into account the risk of smoking. The prevalence of coronary heart disease, heart failure, and rhythm disturbances among COPD patients is significantly higher than in the general population. The article discusses in detail the safety of prescribing various groups of drugs for the treatment of CVD in patients with COPD. Achieving success in understanding and managing patients with COPD and CVD is possible using an integrated multidisciplinary approach.

Airflow Obstruction and Cardio-metabolic Comorbidities

Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction and often co-exists with cardiovascular disease (CVD), hypertension and diabetes. This international study assessed the association between airflow obstruction and these comorbidities. 23,623 participants (47.5% males, 19.0% current smokers, age: 55.1 ± 10.8 years) in 33 centers in the Burden of Obstructive Lung Disease (BOLD) initiative were included. 10.4% of subjects had airflow obstruction. Self-reports of physician-diagnosed CVD (heart disease or stroke), hypertension and diabetes were regressed against airflow obstruction (post-bronchodilator FEV1/FVC < 5th percentile of reference values), adjusting for age, sex, smoking (including pack-years), body mass index and education. Analyses were undertaken within center and meta-analyzed across centers checking heterogeneity using the I2-statistic. Crude odds ratios for the association with airflow obstruction were 1.42 (95% CI: 1.20-1.69) for CVD, 1.24 (1.02-1.51) for hypertension, and 0.93 (0.76-1.15) for diabetes. After adjustment these were 1.00 (0.86-1.16) (I2:6%) for CVD, 1.14 (0.99-1.31) (I2:53%) for hypertension, and 0.76 (0.64-0.89) (I2:1%) for diabetes with similar results for men and women, smokers and nonsmokers, in richer and poorer centers. Alternatively defining airflow obstruction by FEV1/FVC < 2.5th percentile or 0.70, did not yield significant other results. In conclusion, the associations of CVD and hypertension with airflow obstruction in the general population are largely explained by age and smoking habits. The adjusted risk for diabetes is lower in subjects with airflow obstruction. These findings emphasize the role of common risk factors in explaining the coexistence of cardio-metabolic comorbidities and COPD.

Association of Cardiovascular Disease With Respiratory Disease

BACKGROUND

The relationship between respiratory diseases and individual cardiovascular diseases, and the impact of cardiovascular diseases on mortality in patients with respiratory disease, are unclear.

OBJECTIVES

This study sought to determine the relationship between chronic obstructive pulmonary disease (COPD), asthma and interstitial lung disease (ILD), and individual cardiovascular diseases, and evaluate the impact of individual cardiovascular diseases on all-cause mortality in respiratory conditions.

METHODS

The authors conducted a cohort study of all patients admitted to 7 National Health Service hospitals across the North West of England, between January 1, 2000, and March 31, 2013, with relevant respiratory diagnoses, with age-matched and sex-matched control groups.

RESULTS

A total of 31,646 COPD, 60,424 asthma, and 1,662 ILD patients were included. Control groups comprised 158,230, 302,120, and 8,310 patients, respectively (total follow-up 2,968,182 patient-years). COPD was independently associated with ischemic heart disease (IHD), heart failure (HF), atrial fibrillation, and peripheral vascular disease, all of which were associated with all-cause mortality (e.g., odds ratio for the association of COPD with HF: 2.18 [95% confidence interval (CI): 2.08 to 2.26]; hazard ratio for the contribution of HF to mortality in COPD: 1.65 [95% CI: 1.61 to 1.68]). Asthma was independently associated with IHD, and multiple cardiovascular diseases contributed to mortality (e.g., HF hazard ratio: 1.81 [95% CI: 1.75 to 1.87]). ILD was independently associated with IHD and HF, both of which were associated with mortality. Patients with lung disease were less likely to receive coronary revascularization.

CONCLUSIONS

Lung disease is independently associated with cardiovascular diseases, particularly IHD and HF, which contribute significantly to all-cause mortality. However, patients with lung disease are less likely to receive coronary revascularization.

Defining the relationship between COPD and CVD: what are the implications for clinical practice?

Cardiovascular diseases (CVDs) are arguably the most important comorbidities in chronic obstructive pulmonary disease (COPD). CVDs are common in people with COPD, and their presence is associated with increased risk for hospitalization, longer length of stay and all-cause and CVD-related mortality. The economic burden associated with CVD in this population is considerable and the cumulative cost of treating comorbidities may even exceed that of treating COPD itself. Our understanding of the biological mechanisms that link COPD and various forms of CVD has improved significantly over the past decade. But despite broad acceptance of the prognostic significance of CVDs in COPD, there remains widespread under-recognition and undertreatment of comorbid CVD in this population. The reasons for this are unclear; however institutional barriers and a lack of evidence-based guidelines for the management of CVD in people with COPD may be contributory factors. In this review, we summarize current knowledge relating to the prevalence and incidence of CVD in people with COPD and the mechanisms that underlie their coexistence. We discuss the implications for clinical practice and highlight opportunities for improved prevention and treatment of CVD in people with COPD. While we advocate more active assessment for signs of cardiovascular conditions across all age groups and all stages of COPD severity, we suggest targeting those aged under 65 years. Evidence indicates that the increased risks for CVD are particularly pronounced in COPD patients in mid-to-late-middle-age and thus it is in this age group that the benefits of early intervention may prove to be the most effective.

Changes in definition lead to changes in the clinical characteristics across COPD categories according to GOLD 2017: a national cross-sectional survey in China

Purpose

To investigate how the changes of definition in assessment of Global Initiative for Chronic Obstructive Lung Disease (GOLD) stratification 2017 lead to changes of chronic obstructive pulmonary disease (COPD) patient clinical characteristics across categories in China.

Patients and methods

COPD patients from 11 medical centers in China were stratified into old and new groups A–D twice according to the GOLD 2011 and 2017 comprehensive assessment. Demography and clinical characteristics were compared between old and new groups A–D.

Results

In 1,532 COPD patients, the distribution from group A to D was 330 (21.5%), 132 (8.6%), 411 (26.8%), 659 (43.0%) and 557 (36.4%), 405 (26.4%), 184 (12.0%), 386 (25.2%), respectively according to GOLD 2011 and 2017. 46.7% (500/1,070) patients in high-risk groups were regrouped to low-risk groups. Compared to the old groups A and B, the new groups A and B had a higher proportion of males, lower body mass index, higher modified Medical Research Council (mMRC) grade, poor pulmonary function, more patients with chronic bronchitis, and fewer patients with coronary heart disease and hypertension disease. Compared to the old groups C and D, the new groups C and D had older patients, fewer men, better pulmonary functions, frequent acute exacerbations in the previous year, and more patients with chronic bronchitis, coronary heart disease, or diabetes mellitus. The new group D had more patients with stroke than the old group D.

Conclusion

In China, GOLD 2017 shifted the overall COPD comprehensive assessments distribution to more low-risk groups. The new high-risk groups had more characteristics associated with high risk of acute exacerbation and mortality. Some of the changes in demography and clinical characteristics of the new low-risk groups were associated with high risk of acute exacerbation and/or mortality.

The Evaluation of Interstitial Abnormalities in Group B of the 2011 Global Initiative for Chronic Obstructive Lung Disease (GOLD) Classification of Chronic Obstructive Pulmonary Disease (COPD)

Objective In 2011, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification categorized chronic obstructive pulmonary disease (COPD) patients into 4 groups. A report demonstrated that the mortality in Group B was higher than that in Group C. Ischemic heart disease and cancer were suggested to be the cause. The aim of the present study was to test the hypothesis that interstitial lung abnormalities (ILAs) are more prevalent in Group B than Group C and that they may be responsible for the higher mortality in Group B. Methods Patients were selected based on their pulmonary function test results. The inclusion criterion was a forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) of <70% after the inhalation of a bronchodilator. Patients without a smoking history or computed tomography (CT) scan were excluded. The medical records of the patients were retrospectively reviewed, and the selected patients were categorized into Groups A to D. High-resolution CT scans were used to investigate the presence of ILAs and determine the low attenuation area (LAA). Results Among the 349 COPD patients, ILAs were detected in 10.3% of the patients in Group A, 22.5% of the patients in Group B, 5.6% of the patients in Group C, and 23.1% of the patients in Group D. In Group B, the frequency of ILAs was significantly higher and the area affected by the ILAs was significantly greater in comparison to Group C. Among the patterns of interstitial abnormalities, the area of honeycombing in Group B was significantly greater than that in Group C. Furthermore, among the patients in Group B, the LAA in the ILA-positive patients was significantly greater than that in the ILA-negative patients. Conclusion In Group B, the area occupied by ILAs-especially honeycombing-was greater than that in Group C. This contributed to the preserved %FEV1 and possibly to the poorer prognosis of the patients in Group B.

Ischemic ECG abnormalities are associated with an increased risk for death among subjects with COPD, also among those without known heart disease

Abstract presentation

An abstract, including parts of the results, has been presented at an oral session at the European Respiratory Society International Conference, London, UK, September 2016.

Background

Cardiovascular comorbidity contributes to increased mortality among subjects with COPD. However, the prognostic value of ECG abnormalities in COPD has rarely been studied in population-based surveys.

Aim

To assess the impact of ischemic ECG abnormalities (I-ECG) on mortality among individuals with COPD, compared to subjects with normal lung function (NLF), in a population-based study.

Methods

During 2002–2004, all subjects with FEV₁/VC <0.70 (COPD, n=993) were identified from population-based cohorts, together with age- and sex-matched referents without COPD. Re-examination in 2005 included interview, spirometry, and 12-lead ECG in COPD (n=635) and referents [n=991, whereof 786 had NLF]. All ECGs were Minnesota-coded. Mortality data were collected until December 31, 2010.

Results

I-ECG was equally common in COPD and NLF. The 5-year cumulative mortality was higher among subjects with I-ECG in both groups (29.6% vs 10.6%, P<0.001 and 17.1% vs 6.6%, P<0.001). COPD, but not NLF, with I-ECG had increased risk for death assessed as the mortality risk ratio [95% confidence interval (CI)] when compared with NLF without I-ECG, 2.36 (1.45–3.85) and 1.65 (0.94–2.90) when adjusted for common confounders. When analyzed separately among the COPD cohort, the increased risk for death associated with I-ECG persisted after adjustment for FEV₁ % predicted, 1.89 (1.20–2.99). A majority of those with I-ECG had no previously reported heart disease (74.2% in NLF and 67.3% in COPD) and the pattern was similar among them.

Conclusion

I-ECG was associated with an increased risk for death in COPD, independent of common confounders and disease severity. I-ECG was of prognostic value also among those without previously known heart disease.

Chronic Obstructive Pulmonary Disease and Cardiac Diseases. An Urgent Need for Integrated Care

Chronic obstructive pulmonary disease (COPD) is a global health issue with high social and economic costs. Concomitant chronic cardiac disorders are frequent in patients with COPD, likely owing to shared risk factors (e.g., aging, cigarette smoke, inactivity, persistent low-grade pulmonary and systemic inflammation) and add to the overall morbidity and mortality of patients with COPD. The prevalence and incidence of cardiac comorbidities are higher in patients with COPD than in matched control subjects, although estimates of prevalence vary widely. Furthermore, cardiac diseases contribute to disease severity in patients with COPD, being a common cause of hospitalization and a frequent cause of death. The differential diagnosis may be challenging, especially in older and smoking subjects complaining of unspecific symptoms, such as dyspnea and fatigue. The therapeutic management of patients with cardiac and pulmonary comorbidities may be similarly challenging: bronchodilators may have cardiac side effects, and, vice versa, some cardiac medications should be used with caution in patients with lung disease. The aim of this review is to summarize the evidence of the relationship between COPD and the three most frequent and important cardiac comorbidities in patients with COPD: ischemic heart disease, heart failure, and atrial fibrillation. We have chosen a practical approach, first summarizing relevant epidemiological and clinical data, then discussing the diagnostic and screening procedures, and finally evaluating the impact of lung-heart comorbidities on the therapeutic management of patients with COPD and heart diseases.

Lung function, percent emphysema, and QT duration: The Multi-Ethnic Study of Atherosclerosis (MESA) lung study

BACKGROUND

The QT interval on electrocardiogram (ECG) reflects ventricular repolarization; a prolonged QT interval is associated with increased mortality risk. Prior studies suggest an association between chronic obstructive pulmonary disease (COPD) and prolonged QT interval. However, these studies were small and often enrolled hospital-based samples. We tested the hypotheses that lower lung function and increased percent emphysema on computed tomography (CT) are associated with a prolonged QT interval in a general population sample and additionally in those with COPD.

METHODS

As part of the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study, we assessed spirometry, full-lung CT scans, and ECGs in participants aged 45-84 years. The QT on ECGs was corrected for heart rate (QTc) using the Framingham formula. QTc values = 460 msec in women and ≥450 msec in men were considered abnormal (prolonged QT_C). Multivariate regression models were used to examine the cross-sectional association between pulmonary measures and QT_C. RESULTS: The mean age of the sample of 2585 participants was 69 years, and 47% were men. There was an inverse association between FEV₁%, FVC%, FEV₁/FVC%, emphysema, QTc duration and prolonged QTc. Gender was a significant interaction term, even among never smokers. Having severe COPD was also associated with QTc prolongation.

CONCLUSIONS

Our analysis revealed a significant association between lower lung function and longer QTc in men but not in women in a population-based sample. Our findings suggest the possibility of gender differences in the risk of QTc-associated arrhythmias in a population-based sample.

Heart failure and levels of other comorbidities in patients with chronic obstructive pulmonary disease in a Swedish population: a register-based study

Background

Despite the fact that heart failure and chronic obstructive pulmonary disease (COPD) often exist together and have serious clinical and economic implications, they have mostly been studied separately. Our aim was to study prevalence of coexisting heart failure and COPD in a Swedish population. A further goal was to describe levels of other comorbidity and investigate where the patients received care: primary, secondary care or both.

Methods

We conducted a register-based, cross-sectional study. The population included all people older than 19 years, living in Östergötland County in Sweden. The data were obtained from the Care Data Warehouse register from the year 2006. The diagnosis-based Adjusted Clinical Groups Case-Mix System 7.1 was used to describe the comorbidity level.

Results

The prevalence of the diagnosis of heart failure in patients with COPD was 18.8 % while it was 1.6 % in patients without COPD. Age standardized prevalence was 9.9 and 1.5 %, respectively. Standardized relative risk for the diagnosis of heart failure in patients with COPD was 6.6. The levels of other comorbidity were significantly higher in patients with coexisting heart failure and COPD compared to patients with either heart failure or COPD alone. Primary care was the only care provider for 36.2 % of patients with the diagnosis of heart failure and 20.7 % of patients with coexisting diagnoses of heart failure and COPD. Primary care participated furthermore in shared care of 21.5 % of patients with the diagnosis of heart failure and 21.7 % of patients with coexisting diagnoses of heart failure and COPD. The share of care between primary and secondary care varied depending on levels of comorbidity both in patients with coexisting heart failure and COPD and patients with heart failure alone.

Conclusion

Patients with coexisting diagnoses of heart failure and COPD are common in the Swedish population. Patients with coexisting heart failure and COPD have higher levels of other comorbidity than patients with heart failure or COPD alone. Primary care in Sweden participates to a great extent in care of patients with diagnoses of heart failure alone and coexisting heart failure and COPD.

Long-term prognosis of asthma, chronic obstructive pulmonary disease, and asthma-chronic obstructive pulmonary disease overlap in the Copenhagen City Heart study: a prospective population-based analysis

BACKGROUND

Long-term prognosis of patients with characteristics of both chronic obstructive pulmonary disease (COPD) and asthma, named asthma-COPD overlap, is poorly described. We investigated the long-term prognosis of individuals with different types of chronic airway disease, with a special focus on individuals with asthma-COPD overlap.

METHODS

We assigned participants from the Copenhagen City Heart Study into six subgroups: healthy never-smokers, ever-smokers without asthma and COPD, those with asthma with low cumulated smoking exposure and no airflow limitation, those with COPD, those with asthma-COPD overlap with asthma onset before the age of 40 years, and those with asthma-COPD overlap with asthma onset after the age of 40 years. We defined asthma-COPD overlap as current self-reported asthma and a postbronchodilatatory forced expiratory volume in 1 s (FEV1) to forced vital capacity ratio of less than 0·7, without any restrictions regarding smoking. We investigated the course of FEV1 decline for 18 years and risk of admission to hospital due to exacerbations or pneumonias and respiratory and all-cause mortality for 22 years. We analysed FEV1 decline in the six groups using a linear mixed-effects model.

FINDINGS

We included 8382 participants from the Copenhagen City Heart Study in our study: 2199 never-smokers, 5435 ever-smokers, 158 with asthma, 320 with COPD, 68 with asthma-COPD overlap with early-onset asthma, and 202 with asthma-COPD overlap with late-onset asthma. The multivariable-adjusted decline in FEV1 in asthma-COPD overlap with early-onset asthma was 27·3 mL (standard error 5·0) per year, which did not differ significantly from the decline of 20·9 mL (1·2) per year in healthy never-smokers (p=0·19). FEV1 decline in individuals with asthma-COPD overlap with late-onset asthma was 49·6 mL (3·0) per year, higher than the decline in asthma-COPD overlap with early-onset asthma (p=0·0001), the decline of 39·5 mL (2·5) per year in COPD (p=0·003), and the decline in healthy never-smokers (p<0·0001). Hazard ratios for hospital admissions due to exacerbations of asthma or COPD were 39·48 (95% CI 25·93-60·11) in asthma-COPD overlap with early-onset asthma, 83·47 (61·67-112·98) in asthma-COPD overlap with late-onset asthma, 23·80 (17·43-33·50) in COPD, and 14·74 (10·06-21·59) in asthma compared with never-smokers without lung disease (all p<0·0001). Life expectancy was 9·3 years (5·4-13·1) shorter in participants with asthma-COPD overlap with early-onset asthma, 12·8 years (11·1-14·6) shorter in those with asthma-COPD overlap with late-onset asthma, 10·1 years (8·6-11·5) shorter in those with COPD (all p<0·0001), and 3·3 years (1·0-5·5) shorter in those with asthma (p=0·004) than in healthy never-smokers.

INTERPRETATION

Prognosis of individuals with asthma-COPD overlap is poor and seems to be affected by the age of recognition of asthma, being worst in those with late asthma onset (after 40 years of age). Such patients should be followed up closely to prevent fast lung function decline and exacerbations.

FUNDING

Capital Region of Copenhagen, Danish Heart Foundation, Danish Lung Foundation, Velux Foundation, AstraZeneca.

Ischemic heart disease among subjects with and without chronic obstructive pulmonary disease--ECG-findings in a population-based cohort study

Background

Cardiovascular comorbidity in COPD is common and contributes to increased mortality. A few population-based studies indicate that ischemic electrocardiogram (ECG)-changes are more prevalent in COPD, while others do not. The aim of the present study was to estimate the presence of ischemic heart disease (IHD) in a population-based COPD-cohort in comparison with subjects without COPD.

Methods

All subjects with obstructive lung function (COPD, n = 993) were identified together with age- and sex-matched controls (non-COPD, n = 993) from population-based cohorts examined in 2002–04. In 2005, data from structured interview, spirometry and ECG were collected from 1625 subjects. COPD was classified into GOLD 1–4 after post-bronchodilator spirometry. Ischemic ECG-changes, based on Minnesota-coding, were classified according to the Whitehall criteria into probable and possible IHD.

Results

Self-reported IHD was equally common in COPD and non-COPD, and so were probable and possible ischemic ECG-changes according to Whitehall. After excluding subjects with restrictive spirometric pattern from the non-COPD-group, similar comparison with regard to presence of IHD performed between those with COPD and those with normal lung-function did neither show any differences. There was a significant association between self-reported IHD (p = 0.007) as well as probable ischemic ECG-changes (p = 0.042), and increasing GOLD stage. In COPD there was a significant association between level of FEV₁ percent of predicted and self-reported as well as probable ischemic ECG-changes, and this association persisted for self-reported IHD also after adjustment for sex and age.

Conclusion

In this population-based study, self-reported IHD and probable ischemic ECG-changes were associated with COPD disease severity assessed by spirometry.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0149-1) contains supplementary material, which is available to authorized users.

COPD and risk of venous thromboembolism and mortality in a general population

The relationship between chronic obstructive pulmonary disease (COPD) and risk of venous thromboembolism (VTE) has been scarcely studied in the general population. We aimed to investigate the association between COPD and risk of VTE and mortality in a population-based cohort.Spirometry was conducted in 8646 males and females, participating in the fifth (2001-02) and sixth (2007-08) surveys of the Tromsø Study. Incident VTE events during follow-up were registered from the date of inclusion to December 31, 2011. Cox-regression models with COPD stages and confounders as time varying covariates were used to calculate hazard ratios with 95% confidence intervals for VTE and all-cause mortality.During a median follow-up of 6.2 years, 215 subjects developed VTE. Subjects with COPD stage III/IV had a two-fold higher risk of secondary VTE compared to subjects with normal airflow (HR 2.05, 95% CI 1.02-4.10). COPD patients, particularly those with stage III/IV disease, with VTE had a higher mortality rate than COPD patients without VTE (50.2% versus 5.6% per year).Our findings suggest that patients with severe COPD may have increased risk of secondary VTE, and that COPD patients with VTE have a higher mortality rate than COPD patients without VTE.

Risk of cardiovascular comorbidity in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a systemic inflammatory disorder associated with increased comorbid prevalence of cardiovascular diseases. We aimed to quantify the magnitudes of association between overall and specific types of cardiovascular disease, major cardiovascular risk factors, and COPD.

METHODS

We searched Cochrane, Medline, and Embase databases for studies published between Jan 1, 1980, and April 30, 2015, on the prevalence of cardiovascular disease and its risk factors in patients with COPD versus matched controls or random samples from the general public. We assessed associations with random-effects meta-analyses. We studied heterogeneity and biases with random-effects meta-regressions, jackknife sensitivity analyses, assessment of funnel plots, and Egger tests.

FINDINGS

We identified 18,176 unique references and included 29 datasets in the meta-analyses. Compared with the non-COPD population, patients with COPD were more likely to be diagnosed with cardiovascular disease (odds ratio [OR] 2·46; 95% CI 2·02-3·00; p<0·0001), including a two to five times higher risk of ischaemic heart disease, cardiac dysrhythmia, heart failure, diseases of the pulmonary circulation, and diseases of the arteries. Additionally, patients with COPD reported hypertension more often (OR 1·33, 95% CI 1·13-1·56; p=0·0007), diabetes (1·36, 1·21-1·53; p<0·0001], and ever smoking (4·25, 3·23-5·60; p<0·0001). The associations between COPD and these cardiovascular disease types and cardiovascular disease risk factors were consistent and valid across studies. Enrolment period, age, quality of data, and COPD diagnosis partly explained the heterogeneity.

INTERPRETATION

The coexistence of COPD, cardiovascular disease, and major risk factors for cardiovascular disease highlights the crucial need for the development of strategies to screen for and reduce cardiovascular risks associated with COPD.

FUNDING

Canadian Institutes of Health Research.

Lung function impairment increases with age of diagnosis in adult onset asthma

BACKGROUND

Asthma-onset in older individuals has been associated with an accelerated decline in lung function, but direct comparisons with younger adults have not been reported.

METHODS

In a random population sample comprising 4983 individuals from the Copenhagen City Heart Study without asthma at baseline, we compared young (<35 years), middle-aged (35-64 years) and older (>64 years) adults with newly diagnosed asthma during a 10-year follow-up.

RESULTS

The proportion of cases with newly diagnosed asthma during follow-up was similar across age groups (Older adults: 7% (84/1168), middle-aged adults: 7% (223/3147), and young adults: 6% (42/668) (p = ns)). In all three age groups, lung function was reduced at baseline in subjects who were subsequently diagnosed with asthma, but most pronounced in those >35 years. (Mean FEV1%: Young 90.2% (±13.9), middle-aged 80.8% (±20.8), and older adults 80.8% (±24.2), p < 0.001). Furthermore, incident asthma was associated with an accelerated decline in lung function in older adults (young adults 11.0 mL/year, middle-aged adults 18.2 mL/year, and older adults 30.8 mL/year). These differences were independent of FEV1 at baseline and smoking status, and were not explained by undiagnosed asthma in older adults, as the frequency of respiratory symptoms, including wheeze, was similar in all three age groups at baseline.

CONCLUSIONS

Asthma was diagnosed as frequently in older as in younger adults. Preexisting symptoms were equally common, but lung function was more reduced pre-diagnosis, and declined more rapidly in older adults. This emphasizes the need for a high level of therapeutic attention in patients with asthma diagnosed late in life.

Impact of airflow limitation on carotid atherosclerosis in coronary artery disease patients

BACKGROUND

Both airflow limitation and smoking are established cardiovascular risk factors. However, their interaction as risk factors for the development of atherosclerosis in coronary artery disease patients remains unclear.

OBJECTIVES

To evaluate the effect of the interaction between airflow limitation and smoking status on the severity of carotid atherosclerosis.

METHODS

We categorized the 234 enrolled patients with coronary artery disease into four groups: never-smokers with normal pulmonary function (group A), never-smokers with airflow limitation (group B), ever-smokers with normal pulmonary function (group C), and ever-smokers with airflow limitation (group D).

RESULTS

The prevalence of airflow limitation in the enrolled patients was 23.1% (ever-smokers: 15.8%, never-smokers: 7.3%). The prevalence of severe carotid atherosclerosis was 28.2, 29.4, 41.3, and 45.9%, respectively, in the four groups (group D vs. group A, p = 0.035). Even after multivariate adjusting for confounding factors, ever-smokers with airflow limitation were independently associated with severe carotid atherosclerosis (odds ratio 2.89, 95% confidence interval, 1.19-7.00, p = 0.019).

CONCLUSIONS

Ever-smokers with airflow limitation were significantly associated with severe carotid atherosclerosis among patients with coronary artery disease. These findings also provide additional insight into the correlation between airflow limitation and poor cardiovascular clinical outcomes.

Socioeconomic status and prognosis of COPD in Denmark

We investigated the association between length of school education and 5-year prognosis of chronic obstructive lung disease (COPD), including exacerbations, hospital admissions and survival. We used sample of general population from two independent population studies: The Copenhagen City Heart Study and Copenhagen General Population Study. A total of 6,590 individuals from general population of Copenhagen with COPD defined by the Global initiative for obstructive lung disease criteria were subdivided into 4 groups based on the length of school education: 1,590 with education < 8 years; 3,131 with education 8-10 years, 1,244 with more than 10 years, but no college/university education and 625 with college/university education. Compared with long education, short education was associated with current smoking (p < 0.001), higher prevalence of respiratory symptoms (p < 0.001) and lower forced expiratory volume in the first second in percent of predicted value (FEV1%pred) (p < 0.001). Adjusting for sex, age, FEV1%pred, dyspnea, frequency of previous exacerbations and smoking we observed that shortest school education (in comparison with university education), was associated with a higher risk of COPD exacerbations (hazards ratio 1.65, 95% CI 1.15-2.37) and higher risk of all-cause mortality (hazards ratio 1.96, 95% CI 1.28-2.99). We conclude that even in an economically well-developed country with a health care system (which is largely free of charge), low socioeconomic status, assessed as the length of school education, is associated with a poorer clinical prognosis of COPD.

Cardiovascular comorbidity in COPD: systematic literature review

BACKGROUND

Cardiovascular disease (CVD) is common among patients with COPD. However, it is not clear whether this is due to shared risk factors or if COPD increases the risk for CVD independently. This study aimed to provide a systematic review of studies that investigated the association between COPD and CVD outcomes, assessing any effect of confounding by common risk factors.

METHODS

A search was conducted in MEDLINE (via PubMed) for observational studies published between January 1990 and March 2012 reporting cardiovascular comorbidity in patients with COPD (or vice versa).

RESULTS

Of the 7,322 citations identified, 25 studies were relevant for this systematic review. Twenty-two studies provided an estimate for CVD risk in COPD, whereas four studies provided estimates of COPD risk in CVD. The crude prevalence for the aggregate CVD category ranged from 28% to 70%, likely due to differences in populations studied and CVD definitions; unadjusted rate ratio (RR) estimates of unspecified CVD among patients with COPD compared with patients without COPD ranged from 2.1 to 5.0. The association between COPD and CVD persisted after adjustment for shared risk factors in the majority of the studies. Two studies found a relationship between the severity of airflow limitation and CVD risk. Increased RRs were observed for individual CVD types, but their estimates varied considerably for congestive heart failure, coronary heart disease, arrhythmias, stroke, arterial hypertension, and peripheral arterial disease.

CONCLUSIONS

Available observational data support the hypothesis that COPD is associated with an increased risk of CVD.

INDACO project: a pilot study on incidence of comorbidities in COPD patients referred to pneumology units

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) is often associated with comorbidities, especially cardiovascular, that have a heavy burden in terms of hospitalization and mortality. Since no conclusive data exist on the prevalence and type of comorbidities in COPD patients in Italy, we planned the INDACO observational pilot study to evaluate the impact of comorbidities in patients referred to the outpatient wards of four major hospitals in Rome.

METHODS

For each patient we recorded anthropometric and anamnestic data, smoking habits, respiratory function, GOLD (Global initiative for chronic Obstructive Lung Disease) severity stage, Body Mass Index (BMI), number of acute COPD exacerbations in previous years, presence and type of comorbidities, and the Charlson Comorbidity Index (CCI).

RESULTS

Here we report and discuss the results of the first 169 patients (124 males, mean age 74±8 years). The prevalence of patients with comorbidities was 94.1% (25.2% of cases presented only one comorbidity, 28.3% two, 46.5% three or more). There was a high prevalence of arterial hypertension (52.1%), metabolic syndrome (20.7%), cancers (13.6%) and diabetes (11.2%) in the whole study group, and of anxiety-depression syndrome in females (13%). Exacerbation frequency was positively correlated with dyspnea score and negatively with BMI. Use of combination of bronchodilators and inhaled corticosteroids was more frequent in younger patients with more severe airways obstruction and lower CCI.

CONCLUSIONS

These preliminary results show a high prevalence of comorbidities in COPD patients attending four great hospitals in Rome, but they need to be confirmed by further investigations in a larger patients cohort.

Rationale for earlier treatment in COPD: a systematic review of published literature in mild-to-moderate COPD

COPD is progressive and typically begins many years before a definite diagnosis is made. As the rate of decline in lung function may be faster in the initial stages of the disease, early intervention could be beneficial to control symptoms and affect disease progression and outcomes. A systematic review of published literature relating to mild-to-moderate COPD (patients with FEV(1) ≥50% predicted) was performed to evaluate the level of impairment and natural history or disease progression over time, and impact of interventions on the outcomes of patients with early-stage disease. Of the 79 published articles included in this analysis, 31 reported randomized controlled trials; the remaining 48 articles reported studies of non-randomized and/or observational design. Nine of the randomized controlled trials were ≥6 months' duration, enabling assessment of outcomes over time. Most of the randomized controlled trials were in patients with moderate COPD (GOLD stage II); few included patients with the mildest stages of the disease (i.e., stage I). The results show that even patients with milder or moderate COPD can have substantial limitations and physical impairment, which worsen over time. Encouragement of smoking cessation, in conjunction with management of symptoms and treating activity limitation and exacerbations by appropriate non-pharmacologic and pharmacologic management at the earliest possible stage, could positively affect the impact and progression of the disease.

Elevated cardiovascular risk among adults with obstructive and restrictive airway functioning in the United States: a cross-sectional study of the National Health and Nutrition Examination Survey from 2007-2010

BACKGROUND

Reasons for the excess risk for cardiovascular disease among people with chronic obstructive pulmonary disease remain unclear. Our objective was to examine the cardiovascular risk profile for adults with obstructive and restrictive impairments of lung functioning in a representative sample of adults from the United States.

METHODS

We used data from adults aged 20-79 years who participated in the National Health and Nutrition Examination Survey from 2007 to 2010 and had a pulmonary function test. The severity of obstructive impairment was defined by adapting the Global Initiative for Chronic Obstructive Lung Disease criteria.

RESULTS

Among 7249 participants, 80.9% had a normal pulmonary function test, 5.7% had a restrictive impairment, 7.9% had mild obstructive impairment, and 5.5% had moderate or severe/very severe obstructive impairment. Participants with obstructive impairment had high rates of smoking and increased serum concentrations of cotinine. Compared to participants with normal pulmonary functioning, participants with at least moderate obstructive impairment had elevated concentrations of C-reactive protein but lower concentrations of total cholesterol and non-high-density lipoprotein cholesterol. Among participants aged 50-74 years, participants with at least a moderate obstructive impairment or a restrictive impairment had an elevated predicted 10-year risk for cardiovascular disease.

CONCLUSIONS

The high rates of smoking among adults with impaired pulmonary functioning, particularly those with obstructive impairment, point to a need for aggressive efforts to promote smoking cessation in these adults. In addition, adults with restrictive impairment may require increased attention to and fine-tuning of their cardiovascular risk profile.

Prediction of the clinical course of chronic obstructive pulmonary disease, using the new GOLD classification: a study of the general population

RATIONALE

The new Global Initiative for Obstructive Lung Disease (GOLD) stratification of chronic obstructive pulmonary disease (COPD) into categories A, B, C, and D is based on symptoms, level of lung function, and history of exacerbations.

OBJECTIVES

To investigate the abilities of this stratification to predict the clinical course of COPD.

METHODS

Two similar population studies were performed in an area of Copenhagen including 6,628 individuals with COPD.

MEASUREMENTS AND MAIN RESULTS

The patients were monitored for an average period of 4.3 years regarding COPD exacerbations, hospital admissions, and mortality. The percentages of individuals experiencing a COPD exacerbation during the first year of observation were 2.2% in group A, 5.8% in group B, 25.1% in group C, and 28.6% in group D. One- and 3-year mortality rates were 0.6 and 3.8%, respectively, in group A, 3.0 and 10.6% in group B, 0.7 and 8.2% in group C, and 3.4 and 20.1% in group D. Groups B and D, characterized by a higher degree of dyspnea than groups A and C, had five to eight times higher mortality from cardiovascular disease and cancer than did groups A and C.

CONCLUSIONS

The new stratification performs well by identifying individuals at risk of exacerbations. Surprisingly, subgroup B, characterized by more severe dyspnea, had significantly poorer survival than group C, in spite of a higher FEV(1) level. This subgroup warrants special attention, as the poor prognosis could be caused by cardiovascular disease or cancer, requiring additional assessment and treatment.