Describe the chronic respiratory diseases of public health importance.

Chronic Respiratory Disease

• COPD is characterised by persistent, largely irreversible airflow limitation, and encompasses chronic bronchitis and emphysema
• The risk factors in the Indian context:
• Tobacco smoking, particularly bidi smoking, remains the largest single cause
• Indoor air pollution from biomass fuel — wood, dung and crop residue — burnt in unventilated kitchens, which is a major cause of COPD in rural INDIAN women who have never smoked
• That group is the reason the Western smoking-centred model misleads in India, and it should be named explicitly in any answer
• Outdoor air pollution, with several Indian cities among the most polluted in the world
• Occupational dust and fumes — mining, textiles, construction and agriculture
• Childhood respiratory infection and impaired lung growth, and past tuberculosis, which leaves a substantial obstructive deficit and is an important and specifically Indian contributor
• Alpha-1 antitrypsin deficiency, which is rare
• Diagnosis requires spirometry, showing a post-bronchodilator FEV1/FVC ratio below 0.70; COPD is substantially under-diagnosed because spirometry is rarely available at primary level
• Prevention and control — tobacco cessation, which is the only intervention that alters the rate of decline in lung function; clean cooking fuel, which is the key population measure in rural India and is the rationale for the LPG access programme; improved kitchen ventilation and chimney stoves where LPG is not available; occupational dust control; ambient air quality regulation; and influenza and pneumococcal vaccination
• Management — inhaled bronchodilators as the mainstay, with pulmonary rehabilitation, which is effective, cheap and almost entirely unavailable in India, and oxygen for chronic hypoxaemia
• Asthma is a chronic inflammatory airway disease with variable and largely reversible airflow obstruction
• Its triggers — allergens (dust mite, pollen, animal dander, cockroach), respiratory infection, exercise, cold air, smoke, air pollution, occupational agents, drugs including aspirin and beta-blockers, and emotion
• The central problem in India is under-treatment, and it has three causes — under-diagnosis; steroid phobia, both among patients and among prescribers; and a widespread belief that inhalers are a last resort or addictive, so oral medication is preferred
• The correct message is the opposite — inhaled therapy delivers a far smaller dose directly to the airway with fewer systemic effects than tablets, and inhaled corticosteroids are the controller that prevents attacks and deaths
• Reliever medication used frequently indicates poor control and the need for a controller, not for more reliever
• Practical management points — teach and check inhaler technique at every visit, since most patients use it incorrectly; use a spacer, which improves delivery and can be improvised cheaply; provide a written asthma action plan; identify and avoid triggers; and treat the smoking, obesity and rhinitis that worsen control
• Asthma deaths are almost always preventable, and typically follow under-use of controller therapy, over-reliance on reliever, and failure to recognise deterioration
• Biomass smoke causes COPD in women who never smoked, which is why the Western smoking-centred model misleads in India
• Clean cooking fuel is a respiratory intervention, which is the public health rationale for LPG access programmes
• Inhaled therapy gives less drug with fewer effects than tablets, which is the opposite of what patients assume
• Frequent reliever use means poor control, and calls for a controller rather than more reliever
• Check inhaler technique at every visit, since most patients use the device incorrectly
• A spacer improves delivery and can be improvised cheaply, which matters where devices are unaffordable
• Steroid phobia affects prescribers too, not only patients, and is a major cause of under-treatment
• Asthma deaths are almost always preventable, following under-use of controllers and failure to recognise deterioration
• Past tuberculosis leaves obstructive deficit, which is an important and specifically Indian contributor to COPD
• Spirometry is needed for diagnosis and is rarely available, which is why COPD is substantially under-diagnosed
• Only cessation alters the rate of decline in lung function, whatever else is prescribed
• Pulmonary rehabilitation is effective and unavailable, being cheap and almost entirely absent from Indian services
• Give a written action plan, which improves outcomes and costs nothing beyond the consultation time