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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 8  |  Issue : 2  |  Page : 81-87

Is chronic obstructive pulmonary disease under-diagnosed in patients with coronary artery disease? A tertiary care centre experience from central India


1 Department of Respiratory Medicine, Base Hospital Delhi Cantt, New Delhi, India
2 Department of Respiratory Medicine, Shri Guru Ram Rai Institute of Medical and Health Sciences, Dehradun, Uttarakhand, India
3 Department of Respiratory Medicine, Dr DY Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India
4 Department of Respiratory Medicine, Institute of Liver and Biliary Sciences, Vasant Kunj, New Delhi, India
5 Department of Respiratory Medicine, Military Hospital (CTC), Pune, Maharashtra, India
6 Department of Respiratory Medicine, INHS Kalyani, Visakhapatnam, Andhra Pradesh, India

Date of Submission18-Nov-2019
Date of Decision12-Mar-2020
Date of Acceptance12-Apr-2020
Date of Web Publication10-Sep-2020

Correspondence Address:
Dr. M.S. Barthwal
DM, Professor and Head, Department of Respiratory Medicine, Dr DY Patil Medical College, Hospital and Research Centre, Sant Tukaram Nagar, Pune 411018, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jacp.jacp_43_19

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  Abstract 


Context: Although worldwide studies are available regarding the prevalence of COPD in CAD patients, data from India are sparse. Aims: The purpose of this study was to determine the prevalence of undiagnosed and therefore, untreated COPD in patients suffering from CAD. It would also attempt to establish the need for screening of patients diagnosed with CAD for COPD. Settings and Design: A cross-sectional, observational study carried out at the respiratory out patients department (OPD) of a tertiary care centre of armed forces over a period of one year. Methods and Material: 79 patients with angiographically proven CAD underwent spirometry to assess the prevalence of COPD. Statistical Analysis Used: Data analysis was done using SPSS (Statistical Package for Social Sciences) version 21.0. Results: The mean age of the patients was 62.49 years (±8.77). Mean smoking index was 235.88. Nine patients (11.39 %) were diagnosed to have COPD. All the patients diagnosed as COPD were male, >60 years old and had normal BMI. 88.9 % patients with COPD were smokers. On comparing the patients with and without COPD, a significant co-relation was found with LVEF (%) (P = 0.044). 44.4% patients had never been diagnosed with COPD. Conclusions: The prevalence of missed diagnosis of COPD is significant in our study. We recommend that at the time of diagnosis of CAD, the initial evaluation should include a detailed history, clinical examination and evaluation of lung function by spirometry.

Keywords: Chronic obstructive pulmonary disease, coronary artery disease, under-diagnosis


How to cite this article:
Kishore K, Singh A, Barthwal M, Bhattacharyya D, Katoch C, Tyagi R, Rana S. Is chronic obstructive pulmonary disease under-diagnosed in patients with coronary artery disease? A tertiary care centre experience from central India. J Assoc Chest Physicians 2020;8:81-7

How to cite this URL:
Kishore K, Singh A, Barthwal M, Bhattacharyya D, Katoch C, Tyagi R, Rana S. Is chronic obstructive pulmonary disease under-diagnosed in patients with coronary artery disease? A tertiary care centre experience from central India. J Assoc Chest Physicians [serial online] 2020 [cited 2020 Sep 24];8:81-7. Available from: http://www.jacpjournal.org/text.asp?2020/8/2/81/294592



Key Messages: Data regarding the prevalence of COPD in CAD patients from India are sparse. We found the prevalence of COPD in patient of CAD to be 11.39%. We recommend that at the time of diagnosis of CAD, the patients should be screened for co-existent COPD with detailed history, clinical examination and spirometry.


  Introduction Top


Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. It affects around 180 million people throughout the world.[1] In India, according to the Indian study on epidemiology of asthma, respiratory symptoms and chronic bronchitis in adults (INSEARCH), the prevalence of COPD is 3.49% (varying from 1.1% to 10% across various regions of the country).[2] COPD is also associated with various co morbidities, such as, cardiovascular disease (CVD), osteoporosis, lung cancer, diabetes mellitus, anemia, anxiety and depression, among others. Among these, CVD is the most common co-morbidity in a patient with COPD.

Out of all chronic diseases, CVD is the leading killer in India.[3] Also, among cardiovascular diseases, coronary artery disease (CAD) is the most important cause of mortality in the country.[4]

Both COPD and CAD being common ailments affecting Indians, there are a number of cases where these two diseases co-exist. There is a definite association between COPD and CAD. The presence of CAD increases the mortality and frequency of exacerbations in patients with COPD and vice versa, that is, in patients with CAD, the presence of COPD and exacerbations increase mortality.[5] The cause of this link between the two is multi-factorial. Both diseases are associated with increasing age, tobacco smoking and sedentary lifestyle.[5] The various factors considered to be responsible are systemic inflammation, hypoxemia, lung hyperinflation, exacerbations and common risk factors, among others.[6],[7] Also, COPD has been shown to be an independent risk factor for cardiovascular disease.[8] In patients with CVD, COPD exacerbations increase the risk of further cardiovascular events.[9] Increased inflammatory response during an exacerbation leads to the release of mediators such as fibrinogen and interleukin-6 (IL-6), reduction in levels of CD34+ cells and platelet activation and thrombosis, all responsible for obstruction to the cardiac vascular supply.[5]

The symptom profile (dyspnea, fatigue and cough) of both these conditions is also similar, leading to delays in diagnosis. A missed diagnosis of COPD in a patient with CAD and vice versa is a common error and leads to increased morbidity and mortality.[10] COPD being a treatable disease, patients with CAD who also have COPD suffer an unnecessary disease burden. Therefore, early diagnosis and treatment of COPD in patients with CAD is advisable.

Although worldwide studies are available regarding the prevalence of COPD in CAD patients, data from India are sparse. In this study, we have evaluated patients with angiographically proven CAD for the presence of COPD [as defined by Global Initiative for Chronic Obstructive Lung Disease (GOLD)], and to ascertain whether these patients were previously diagnosed or undiagnosed cases of COPD.


  Subjects and methods Top


This was a cross-sectional, observational study carried out at the respiratory out patients department (OPD) of a tertiary care centre of Armed Forces over a period of one year. Subjects aged 40-75 years, selected by systematic random sampling from patients with a diagnosis of CAD attending OPD at Cardiology and Cardiothoracic surgery departments of this centre were included in the study. The diagnosis of CAD was confirmed by angiography as the presence of obstructive disease. Patients with a history of myocardial infarction within past month or having unstable angina or those who were unable to perform spirometry were excluded from the study.

Data was collected using a questionnaire to include demographics [age, gender, height, weight, body mass index (BMI)] and smoking status (including smoking index). Smoking index was used to grade smoking exposure as follows[11]:

Mild : <100

Moderate : 100 to 300

Heavy : >300

For assessing the cardiac status, New York Heart Association (NYHA) grading of symptoms,[12] standard two-dimensional echocardiography [to measure left ventricular ejection fraction (LVEF), dimensions of chambers, right ventricular end diastolic diameter, right ventricular systolic pressure, valvular dimensions and any regional wall motion abnormality (RWMA)], and coronary angiography was done.

All patients were assessed for symptoms suggestive of COPD (dyspnea, cough and sputum production) and prior diagnosis of COPD (including basis of diagnosis, status of follow up and treatment for COPD). Dyspnea was graded as per the modified Medical Research Council (mMRC) grading.[13] All subjects performed a post bronchodilator spirometry maneuver. Jaeger Master Screen computerised Body Plethysmograph (Body box) was used for spirometry. Standardization of spirometry was based on American Thoracic Society/ European Respiratory Society (ATS/ERS) task force joint statement on standardization of spirometry (2005).[14] The presence of irreversible airflow limitation was confirmed by a post bronchodilator forced expiratory volume in first second/ forced vital capacity (FEV1/FVC) ratio <0.70. All patients with post bronchodilator FEV1/FVC <0.70 were diagnosed as having COPD.[15] Severity of airflow limitation was classified as[15]:

Mild: FEV1 ≥ 80% predicted

Moderate: FEV1 ≥ 50% and < 80% predicted

Severe: FEV1 ≥ 30% and < 50% predicted

Very Severe: FEV1< 30% predicted

Data analysis was done using SPSS (Statistical Package for Social Sciences) version 21.0. Continuous variables were expressed as mean and standard deviation (SD), while categorical variables were expressed as frequency and percentage. Qualitative variables were compared using chi-square test and Fisher’s exact test as appropriate. A P-value of < 0.05 was considered statistically significant.


  Results Top


Demographic profile

A total of 79 patients selected from patients of CAD at our centre who met the inclusion criteria were included for statistical analysis. The mean age of the patients was 62.49 years (±8.77) [Table 1]. Maximum patients were in the age group 61–70 years (44.3%). 67 patients (84.8 %) were males and 12 (15.2 %) were females. 51 patients (64.6 %) in the study group had normal BMI, 2.5 % were underweight, 24 % were overweight and 8.9 %were obese. 43 % were smokers and 57 % were non-smokers. All the smokers were males. 23.5% were heavy smokers. Mean smoking index was 235.88.
Table 1 Demographic profile of study population

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Cardiac status

Majority of patients were in NYHA class II (51.9 %) [Table 2]. 29.1% patients had single vessel disease (SVD), 17.7% had double vessel disease (DVD) and 53.2% had triple vessel disease (TVD). 12 patients had undergone coronary artery bypass grafting (CABG). On echocardiography, 2.5 % patients had a normal left ventricular ejection fraction (LVEF > 60 %), 93.7% had LVEF between 40 and 60% and 3.8% had LVEF < 40%. RWMA were noted in 33 patients (41.8%).
Table 2 Profile of CAD in study population

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COPD among CAD patients

After spirometry, out of 79 patients in the study group, nine patients (11.39%) were diagnosed to have COPD. The severity of airway obstruction in these patients is shown in [Table 3].
Table 3 Severity of airway obstruction in COPD patients

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Of the nine patients with COPD, six patients (66.7%) were symptomatic with cough, sputum production and breathlessness. Two patients (22.2%) were symptomatic only with breathlessness and one patient (11.1%) was asymptomatic. The most common symptom was breathlessness (88.9%), followed by cough and sputum production (66.7%) each.

All the patients diagnosed as COPD were male, >60 years old and had normal BMI. 88.9% patients with COPD were smokers [Table 4].
Table 4 Demographic profile of COPD patients

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Status of CAD in COPD patients

All the patients with COPD had EF<60%, but RWMA was present in a single patient [Table 5]. Most of them had SVD (45%). On comparing the patients with and without COPD, a significant co-relation was found with LVEF (%) (P = 0.044), rest of the variables had no significant co-relation [Table 6]. Analysis of the patients with COPD revealed no significant co-relation between disease severity and other variables (LVEF, NYHA class, RWMA, etc.).
Table 5 Profile of CAD in COPD patients

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Table 6 Association between COPD and variables

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Underdiagnosis of COPD

Five of these nine patients (55.6%) had a prior diagnosis of COPD. Out of these, two patients were on correct treatment for COPD. One patient was not on any treatment and two were receiving inappropriate treatment. Thus, despite having been diagnosed with COPD, 60% patients were not on appropriate medication. 44.4% patients had never been diagnosed with COPD.


  Discussion Top


The mean age of patients was 62.49 (SD: 8.77) years, similar to findings from studies conducted in India as well as abroad. Maximum patients were in the age group 61–70 years (44.3%). The majority (84.8%) of patients were male, which is a similar finding reported by two previous Indian studies conducted by Mahendra et al. and Agarwal et al.[16],[17] It is understandable as CAD and tobacco smoking, both are more common among males.

Although more than half the patients had normal BMI, 24% were overweight and 9% were obese. The association between obesity and cardiovascular disease is well established. On the other hand, it has been shown that obesity plays a protective role (against mortality) in GOLD stage 3 and 4, while it increases the relative risk for mortality in GOLD stages 1 and 2.[18]

Tobacco smoking is linked with both cardiovascular disease and obstructive airway disease. In our study, around half the patients (43%) were smokers. This is lesser than that reported by Indian (71%, Mahendra et al.) and international studies (72.6%, Khasswaneh et al.).[16],[19] All the smokers were male and majority of them were moderate (61.7%) and heavy (23.5%) smokers.

On assessing the cardiac status, most of the patients had moderate to severe coronary disease. More than half the patients (51.9%) were in functional class II and around 30% were in functional class III. On angiography, maximum number of patients (53.2%) had triple vessel disease, 29% had SVD and 14% had DVD. Similar data was reported by a recent Indian study.[17] On echo, ∼98% patients had reduced EF (<60%), while 42% had RWMA.

Out of 79 patients with stable CAD, 9 (11.39%) had COPD on spirometry. Majority of these (78%) had moderate airflow limitation. All the patients diagnosed as COPD were male, >60 years old and had normal BMI. 88.9% patients with COPD were smokers. Seven out of these nine (77.8%) had moderate to heavy exposure to smoking. Early diagnosis of COPD can be helpful in advising smoking cessation. Early and strong emphasis on smoking cessation will provide the only chance for reducing lung damage in COPD.[20] The benefits of smoking cessation in both CAD and COPD cannot be over emphasized.

On evaluating the cardiac status of patients with COPD, maximum number of them (78%) were in NYHA functional class II, all of them had EF<60%, but RWMA was present in a single patient. Most of them had SVD (45%). Dyspnea (89%) and cough (67%) were reported by majority of patients and only one patient was asymptomatic.

A previous Indian study by Mahendra et al.[16] reported a similar prevalence of 11.4% of COPD among stable IHD patients (none of the cases were previously diagnosed). [Table 7] provides a comparative analysis of recent studies conducted across the world for assessment of burden of COPD among patients with cardiac disease. Agarwal et al.[17] reported a prevalence of 22.5%, although their study population comprised of CAD patients who were non-smokers. Studies from outside India have reported a COPD prevalence varying from 7% to 33.6% among ischemic heart disease patients.[19],[21],[22],[23],[24] In another study from Japan, with a large number of patients (995), the prevalence of airflow limitation (AL) was reported to be 27%, although pulmonary function testing (PFT) was done using a hand held spirometer and a FEV1/FEV6 < 0.73 was defined as AL.[25] Also, they had included all patients with CVD (including myocardial infarction, hypertension, angina and arrhythmia).On comparing the patients with and without COPD, a significant co-relation was found with LVEF (%) (P = 0.044), rest of the variables had no significant co-relation. Agarwal et al also found no association between severity of COPD and CAD.[17] Mahendra et al reported that IHD patients with COPD had lesser BMI (P = 0.008), no other significant association was found among variables.[16]
Table 7 Comparison of similar studies.

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In our study, 55.6% patients had a prior diagnosis of COPD, out of which only 22% were receiving correct treatment. 44.4% patients were newly diagnosed as COPD cases during the study period. Previous studies have reported similar data for under diagnosis and under treatment of COPD among patients with ischemic heart disease.[16],[19],[23],[24],[25] So, around 12% patients with CAD had co-existent COPD (missed diagnosis), out of which only 50% were previously diagnosed (under-diagnosis) and among those only 22% were receiving appropriate COPD treatment (under-treatment). Inability to identify such patients is detrimental. Treatment for COPD not only improves quality of life, but also reduces future cardiovascular risk and mortality. Timely identification of the presence of obstructive airway disease as soon as the patient’s cardiac status stabilizes and prompt treatment will reap good benefits in reducing morbidity and mortality in the long run.

Our study had certain shortcomings. It had a small sample size and was conducted at a single centre, so the results cannot be generalized to the whole population. Secondly, it was a cross-sectional study, so a causal relationship between COPD and CAD could not be established. Thirdly, the patients attending OPD at a tertiary care hospital are more likely to have advanced cardiac disease. Selection of patients from this population is likely to cause selection bias.

We found a COPD prevalence of around 12% among patients with coronary artery disease. The prevalence of this missed diagnosis is significant. It puts unnecessary disease burden on these patients. We recommend that at the time of diagnosis of CAD, the initial evaluation should include a detailed history, clinical examination and evaluation of lung function by spirometry. Patients diagnosed as COPD should be referred to a chest physician for smoking cessation counselling and initiation of appropriate treatment as relief of airflow limitation causes improved cardiovascular status. Further larger scale studies are mandated to consolidate our findings.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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