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Chronic Obstructive Pulmonary Disease ( COPD )

Chronic Obstructive Pulmonary Disease ( COPD ) is a common, preventable and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and / or alveolar abnormalities usually caused by significant exposure to noxious particles or gases and influenced by host factors including abnormal lung development ( GOLD 2020 )

COPD is an umbrella term that includes a diverse group of conditions with a common feature-obstructive ventilatory disorders

Chronic bronchitis –With an obstructive ventilatory pattern that is chronic bronchitis with permanent obstruction of airways ie FEV1 / FVC ratio of < 70 %

Chronic respiratory failure -With an obstructive ventilatory pattern that is chronic bronchitis with permanent obstruction of airways ie FEV1 / FVC ration of < 70 %

Emphysema -Defined at the anatomical level- the destruction of the walls of the alveolar sacs / ducts distal to terminal bronchiole with an abnormal increase in the size of distal airways. Two patterns can be seen (1) centrilobular -associated with cigarette smoking (2 ) Panlobular see more often with α 1-antitrypsin deficiency

How common – Prevalence may vary widely as survey methods , diagnostic criteria and analytical approaches may differ A disease seen mostly in smokers > 40 yrs old age It is also important to note that a substantial proportion of people with COPD have never smoked , the proportion of this cohort has been reported widely from 3% to 45 % It is known that the prevalence increases with age -a 5 fold increase for those aged >65 in comparison to those <40 COPD is currently the 3rd most common cause of morbidity and mortality worldwide and led to 3.23 million deaths in 2019 It affects about 4.5 % of UK adults over 40 COPD causes nearly 30,000 deaths a year or around 5.3 % of all UK deaths Investigators have also reported that nearly 90 % of COPD deaths worldwide occur in low income and middle income countries British Lung Foundation estimates that 1.2 million people have been diagnosed with COPD and this represents about a 3rd of people who have been diagnosed and many are yet undiagnosed It is thought that the burden of COPD is much higher than previously estimated

Serious global public health problem COPD remains an important cause of morbidity and mortality in countries at all levels of economic development Number of deaths from COPD in 2017 was 3.2 million people-a 23 % rise when compared to deaths in 1990 It is also thought that COPD is underdiagnosed and under-treated High use of healthcare resources and it is a common cause of hospital admission COPD often co-exists with other conditions -which can have a severe impact on the course of the disease Complications / deaths related to COPD continue to risk 

GOLD ( Global Initiative for Chronic Obstructive Lung Disease ) is a collaboration between NILH ( National Heart , Lung , and Blood Institute USA , NIH ( National Institute of Health USA and the WHO ( World Health Organization ) launched in 1997. 

Cigarette smoking most common established ,modifiable risk factor pipe , cigar , water-pipe ( hukka ) , marijuana etc are also risk factors passive smoking ( also called as environmental tobacco smoke ETS ) may also contribute to respiratory symptoms of COPD Second-hand smoke exposure during childhood is particularly considered an important risk factor worldwide smoking during pregnancy may pose risk to fetus cigarette smoking can cause interstitial fibrosis , increased secretion from mucous glands and obstructive bronchiolitis , stimulates the lung to produce large amounts of reactive oxygen species ( ROS ) which can lead to an imbalance of the oxidation and anti-oxidant systems Cell apoptosis and cell dysfunction studies in China has shown that smoking more than 20 pack years triples the prevalence of it is estimated that about 50 % of smokers develop COPD

Other noxious substances – indoor and outdoor air pollution among the ambient air pollutants fine particulate matter less than 2.5 µm in aerodynamic diameter ( PM 2.5 ) has the greatest effect on respiratory health it is known that almost 3 billion people use solid fuel ie wood , charcoal , crop residues , animal dung etc for cooking / heating homes ( called biomass fuel ) which contributes significantly to household air pollution occupational exposure (vapours, gas , dust , fumes -VGDF, organic , inorganic dust ) – it has been found that OP contributes more substantially to the burden of COPD in non-smokers and smoking and occupation act as additive risks for COPD studies to identify occupations at risk are ongoing and causal associations with coal dust , silica construction dust , cotton dust , asbestos and grain dust have been noted

Genetic factors – best studied is the link between COPD and severe hereditary deficiency of alpha -1 antitrypsin ( AATD ) which is a major circulating inhibitor of serine proteases AATD is rare and causes emphysema -the lung is at risk for protease mediated damage ( AATD should be suspected in COPD patients who also have liver damage ) several other genes have been implicated but no consistent associations have been found 

Asthma and airway hyper-reactivity several studies have shown that asthma may be a risk factor for COPD development patients with COPD with concomitant asthma experience poor QoL and greater dyspnoea studies have also shown that airway hyper-responsiveness can be a risk factor for COPD

Bronchitis -it has been noted that younger adults who smoke -presence of chronic bronchitis increases the risk of COPD chronic bronchitis is also known to be associated with an increased risk in total number of infections and severity of exacerbations

Lung development -severe respiratory infections in childhood can be associated with reduced lung function and increased respiratory symptoms in adulthood maternal smoking / low birth weight /premature birth

Low socioeconomic status -strong relationship between individuals socioeconomic status and COPD has been identified, particularly in low and middle income countries GOLD mentions that risk of developing COPD is inversely related to socioeconomic status

Assessment -Presentation can be with progressive shortness of breath , cough and sputum production Consider diagnosis if they present with above symptoms and have a h/o exposure to risk factors for the disease Spirometry is required ( GOLD ) for making a diagnosis of COPD ( this may also be a limiting factor in reaching a diagnosis ) showing airflow limitation A post-bronchodilator FEV1 / FVC ratio of < 0.70 confirms the presence of persistent airflow limitation 

 

Medical history –Points to note in medical history exposure to risk factors detailed previous medical history – GOLD suggests to focus on aspects in history as ○ asthma ○ allergy, sinusitis or nasal polyps ○ respiratory infections in childhood ○ chronic respiratory & non-respiratory diseases is there a family h/o COPD or other chronic respiratory disease? identifiable patterns as increased breathlessness, winter colds , social restrictions have they been hospitalised before for breathing problems do they suffer with any comorbid conditions as heart disease , osteoporosis , MSK disorders or cancer ? how does the condition impact on patient’s QoL ? ie limitations including social impact 

Differentials -Asthma Asthma / COPD overlap syndrome Congestive heart failure Bronchiectasis Tuberculosis Interstitial lung disease Obliterative bronchiolitis Diffuse panbronchiolitis Thromboembolic disease Cystic fibrosis Malignancy

Some important complications / comorbidities -Pulmonary artery disease : pulmonary hypertension Lung cancer -seen frequently in COPD patients and is a leading cause of death Vascular and heart diseases ( CVD ) commonly seen co-morbidities ( smoking-share common risk factor ) co-existence is associated with worse outcomes than either condition alone Heart failure patients with co-existent COPD suffer with worse outcomes Predisposition to venous thromboembolism Recurrent pneumonia Osteoporosis Depression / anxiety Cognitive impairment Metabolic syndromes and diabetes Sleep disturbances ( OSAS ) Respiratory failure Pneumothorax Polycythemia Malnutrition Anaemia Lung fibrosis ( smoking common risk factor )

Please also refer to the NICE guidance on diagnosis and management of COPD Note that NICE recommends an assessment starting age 35 whrease GOLD recommends a suspicion of COPD starting age 40 

REFERENCES

  1. *GOLD-2020-REPORT-ver1.1wms.pdf (goldcopd.org)
  2. Wim Timens,Pathology of Chronic Obstructive Pulmonary Disease,Editor(s): Sam M Janes,
    Encyclopedia of Respiratory Medicine (Second Edition),Academic Press,2022,Pages 533-548,
    ISBN 9780081027240,https://doi.org/10.1016/B978-0-08-102723-3.00044-5. ( Abstract )
    (https://www.sciencedirect.com/science/article/pii/B9780081027233000445)
  3. Epidemiology of COPD | European Respiratory Society (ersjournals.com)
  4. *GOLD-2019-POCKET-GUIDE-DRAFT-v1.7-14Nov2018-WMS.pdf (goldcopd.org)
  5. Epidemiology and risk factors of chronic obstructive pulmonary disease in Suzhou: a population-based cross-sectional study – Yan – Journal of Thoracic Disease (amegroups.com)
  6. Chronic Obstructive Pulmonary Disease Overview | Epidemiology, Risk Factors, and Clinical Presentation | Proceedings of the American Thoracic Society (atsjournals.org)
  7. Risk factors | Background information | Chronic obstructive pulmonary disease | CKS | NICE
  8. Prevalence and risk factors of chronic obstructive pulmonary disease in China (the China Pulmonary Health [CPH] study): a national cross-sectional study – The Lancet ( Abstract )
  9. *rccm2008111757st 693..718 (thoracic.org)
  10. COPD 1: pathophysiology, diagnosis and prognosis | Nursing Times
  11. Chronic obstructive pulmonary disease (COPD) – Symptoms, diagnosis and treatment | BMJ Best Practice
  12. Laniado-Laborín, Rafael. “Smoking and chronic obstructive pulmonary disease (COPD). Parallel epidemics of the 21 century.” International journal of environmental research and public health vol. 6,1 (2009): 209-24. doi:10.3390/ijerph6010209
  13. Comorbidities of COPD | European Respiratory Society (ersjournals.com)
  14. Cai, L., Wang, XM., Fan, LM. et al. Socioeconomic variations in chronic obstructive pulmonary disease prevalence, diagnosis, and treatment in rural Southwest China. BMC Public Health 20, 536 (2020). https://doi.org/10.1186/s12889-020-08687-5

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