Summary

Chronic obstructive pulmonary disease (COPD) is a major cause of chronic morbidity and mortality and further increases in its prevalence and mortality are expected in the coming decades. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) had been issued since 2001 with aims to improve the diagnosis, prevention and management of COPD. Early identification of COPD can improve outcome. Smoking cessation remains an effective strategy in slowing the accelerated decline of lung function. Long acting bronchodilators and combined treatment with inhaled corticosteroids provide significant symptom relief, reduce exacerbations and potentially reduce hospitalization and mortality. Pulmonary rehabilitation is recommended to patients with moderate or more severe COPD with significant benefits in multiple dimensions including dyspnoea, exercise capacity, health status and healthcare utilisation. To achieve optimal disease management, case finding and integrated care by primary and secondary care physicians with introduction of rehabilitation elements is important.

摘要

慢性阻塞性肺病(COPD)是一種主要慢性及可致命的疾病。而其患病率和死亡率在未來數十年預計還會進一步上升。在2001年開始的“慢性阻塞性肺病全球行動”，旨在改善COPD的診斷、預防和治療。及早診斷COPD能改善病人的結果，而戒煙仍是延緩肺功能衰退的有效對策。長效支氣管擴張劑和皮質激素吸入綜合療法可顯著地緩解症狀、減少病情惡化，從而減少住院和死亡。對中重度COPD病人進行肺康復治療，可以在呼吸困難、活動能力、健康狀況和醫療服務的需要等多方面帶來明顯益處。為達到疾病的最佳治療效果，個案的識別，社區醫療與住院服務的融合，吸引進康復服務都是重要的。

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Introduction

Chronic obstructive pulmonary disease (COPD) is a major cause of chronic morbidity and mortality and represents a significant drain of social resources. It is the fifth leading cause of death worldwide and further increases in its prevalence and mortality are expected in the coming decades.¹ Based on the COPD prevalence estimation model, the projected prevalence rate of COPD in an Asian study of 12 countries is 6.3% and is 3.5% in Hong Kong.² However, these figures should be under-estimated as the disease is not usually recognised until it is clinically apparent and moderately advanced.

COPD is a preventable and treatable disease characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking.³ Although COPD affects the lungs, it also produces significant systemic consequences.

Through concerted worldwide effort, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) was issued in 2001 with an annual update and served as evidence based guidelines for the diagnosis, prevention and management of COPD.⁴ The objectives of GOLD are to raise the awareness of COPD, improve prevention and management of the disease, decrease morbidity and mortality and encourage research in the disease.

There are four essential components of management of stable COPD: disease diagnosis and staging, smoking cessation, management of stable chronic COPD (pharmacological and non-pharmacological therapies) and exacerbation management.

Diagnosis and staging

Diagnosis of COPD should be considered in any patient with a history of exposure to risk factors (especially tobacco smoke, occupational dusts and chemicals, indoor or outdoor pollution) who has any of the respiratory symptoms (chronic cough, chronic sputum production, dyspnoea).⁴ Spirometry is the gold standard for diagnosing COPD and disease monitoring as it is standardized, reproducible and the most objective measurement of airflow limitation. COPD is confirmed by a post-bronchodilator FEV₁/FVC ratio < 70% that is not fully reversible.⁵ Primary care physicians should have access to spirometry for the diagnosis and monitoring of COPD.

The disease is classified into five different stages as shown in Table 1.⁴ GOLD has recommended specific management strategies according to the spirometric staging of COPD (Table 2). Together with dyspnoea, body mass index and exercise capacity index, the degree of airflow obstruction is proved to be useful in predicting the mortality⁶ and hospitalization⁷ in COPD.

Smoking cessation

Early identification of COPD in the course of the disease can improve outcome. It is necessary to reduce personal exposure to cigarette smoke, occupational dusts and chemicals, both indoor and outdoor air pollutants. Smoking cessation remains an effective strategy to slow down the rate of accelerated decline in lung function.^8,9 Health care professionals should ask (systematically identify all tobacco users at every visit), advise (strongly urge all tobacco users to quit), assess (determine willingness to make a quit attempt), assist (aid the patient in quitting) and arrange (schedule follow up visit) whenever feasible.¹⁰ The smoking cessation intervention is effective for smokers and should be practised in all clinical settings including primary care.^4,10 The addition of nicotine replacement therapy (NRT) may further increase quit rates. All of the commercially available forms of NRT (nicotine gum, transdermal patch, nicotine nasal spray, nicotine inhaler, sublingual tablets / lozenges) are effective as part of a strategy to promote smoking cessation.¹¹ They increase the odds of quitting approximately 1.5 to 2 fold regardless of clinical setting and GOLD recommended the prescription of NRT in the absence of contraindications.⁴

Management of stable COPD: pharmacological management

Medications currently available for COPD can reduce or abolish symptoms, increase exercise capacity, reduce the number and severity of exacerbations and improve health status.⁵ Bronchodilators are the cornerstone of symptom management in COPD. Although oral bronchodilators are commonly prescribed at general practice, inhaled bronchodilators therapy are preferred.^4,5 Adverse effects are more likely and resolve more slowly after treatment withdrawal, with oral than inhaled treatment; especially the current COPD population tend to be old and more likely to have comorbidities.

Inhaled anticholinergic medications have additive effects when combined with inhaled short acting beta-2 agonists and both are recommended in COPD guidelines. However, the effects of the inhaled short acting anticholinergic, alone or when combined with beta 2 agonists, on lung function, symptoms and exercise tolerance are small according to the Cochrane review.¹²

On the other hand, long acting beta-2 agonists (LABA e.g. salmetrol and formoterol) are more useful bronchodilators for maintenance use in moderate or more severe stages of COPD.^3,4 LABA when combined with inhaled corticosteroids (e.g. fluticasone or budesonide) are more effective in improving airflow obstruction, reducing the overall symptoms, improving health-related quality of life and reducing exacerbations.^13,14

Tiotropium is a once daily anti-cholinergic bronchodilator that cause prolonged blockage of the M₃-muscarinic receptor and improves FEV₁ significantly more than the short acting anticholinergic. It also improves lung hyperinflation, dyspnoea and exercise tolerance in COPD.¹⁵ It reduces COPD exacerbation (OR 0.74; 95% CI 0.66 to 0.83) and related hospitalisations (OR 0.64; 95% CI 0.51 to 0.82) as compared to placebo or ipratropium.¹⁶ The effects of tiotropium on lung function appears promising while long term studies on its effect on lung function^17,18 and mortality are being carried out.

Although theophylline has been relegated in major guidelines, it remains a common and useful treatment in COPD management.^4,5 Theophylline has a modest effect on FEV₁ and FVC and slightly improves arterial blood gas tensions in moderate to severe COPD.¹⁹ However, the benefits of theophylline in COPD should be weighed against the risk of adverse effects e.g. tremor and tachycardia.

Bronchodilators can be prescribed on an as-needed or on a regular basis to prevent or reduce symptoms while the choice between beta-2 agonist, anti-cholinergic, theophylline, or combination therapy depends on the availability and individual response in terms of symptom relief and side effects. It appears that both LABA and tioptropium are effective treatment for COPD but are more expensive.

The role of inhaled corticosteroids (ICS) in COPD remains controversial. Four large controlled trials of 3 year duration have demonstrated no significant effect of ICS on the loss of lung function that occurs in COPD.²⁰ However, evidence showed that steroids could reduce exacerbations in severe COPD disease^20-22 and its associated mortality.^21-22 The latest GOLD guidelines recommended ICS for the management of severe and very severe staged COPD patients with frequent exacerbations. The "Towards a Revolution in COPD Health" (TORCH)" multicentre, randomised, double-blind survival study had been carried out in 6,200 COPD subjects to examine the impact of inhaled corticosteroids (fluticasone) and long-acting bronchodilators (salmeterol), alone or in combination, on reduction of all-cause mortality over 3 years.²³ TORCH will help to answer the question of whether pharmacologic interventions are effective in changing the clinical course of COPD.

Mucolytics are commonly prescribed by family physicians but their effects on lung function or symptoms are uncertain. However, a recent Cochrane collaborative review showed that mucolytics was associated with a small reduction in acute exacerbations and a reduction in total number of days of disability in COPD subjects.²⁴ Mucolytics can be considered in individuals who have frequent or prolonged exacerbations, or frequent admissions to hospital with exacerbations of COPD.

Management of stable COPD: pulmonary rehabilitation

Pulmonary rehabilitation (PR) has been established in Hong Kong for more than 10 years and is increasingly recommended for the COPD management. It is defined as "an evidence-based, multidisciplinary and comprehensive intervention for patients with chronic respiratory diseases who are symptomatic and often have decreased daily life activities. Integrated into the individualized treatment of the patient, pulmonary rehabilitation is designed to reduce symptoms, optimize functional status, increase participation, and reduce health care costs through stabilizing or reversing the systemic manifestations of the disease."²⁵

The physical, psychological and social problems in COPD create a vicious cycle and further compromise patient's health status and quality of life. However, much of these secondary morbidities e.g. cardiac deconditioning, peripheral muscle dysfunction, malnutrition, social isolation and depression are amendable to treatment if recognized. Rehabilitation aims to tackle these multiple problems through a comprehensive programme that consists of education, physical training, psychological and social support, nutritional therapy and outcome assessment.²⁵

Rehabilitation can achieve significant and clinically meaningful improvements in multiple outcome areas including dyspnoea, exercise ability, health status and healthcare utilisation.²⁶ These positive effects occur despite a minimal effect on the lung function measurements. The Cochrance meta-analyses support rehabilitation training for four weeks or more as part of the comprehensive COPD management.²⁷ Rehabilitation should be considered for COPD patients who have dyspnoea, reduced exercise tolerance, limitation in daily living, leisure, social or occupational activities and impaired health status.^4,25 There are no specific pulmonary function inclusion criteria for the therapy since symptoms and functional limitations direct the need for rehabilitation. GOLD has incorporated PR as a standard therapy for moderate or more severe COPD patients in its revised guidelines and the treatment is effective irrespective of age and disease staging.

Management of COPD exacerbations

The majority of COPD exacerbations are managed at home by patients or by the primary care physicians. Patients should be educated the symptoms of an exacerbation and encouraged to report these early to clinicians. Physicians should look for the early signs of an exacerbation and differentiate if infective element is present or not. A short course of oral corticosteroids can be given for exacerbation^3,4,28 while antibiotics can be given when associated with increased sputum amount and purulence.²⁹ In addition, influenza vaccination may reduce exacerbations and hence recommended for COPD patients.³⁰

Integrated disease management for primary care

COPD is a chronic and progressive disease and the "integrated care" of the disease involves the patient and a team of clinical professionals cooperating with secondary care and rehabilitation services. "Optimal disease management" involves redesigning standard medical care to integrate rehabilitative elements into a system of patient self-management and regular exercise. "Case finding" is a simple and effective means of enhancing the diagnosis of COPD in primary care.⁵ Symptom based questionnaires with history of smoking and exposure of dusts or chemical can be helpful to identify persons for whom spirometric testing may be appropriate but more importantly the awareness of the disease should be raised among medical practitioners. Use of spirometry is recommended for early detection of airway obstruction which is feasible in primary care setting, provided that personnel are trained and quality assurance is maintained. Education, smoking cessation, pharmacological and non-pharmacological interventions can be followed in the integrated care pathway once the disease is diagnosed.

Conclusion

The prevalence of COPD is underestimated and medical practitioners should aim to diagnose COPD early in its clinical course using spirometric measurements. Smoking cessation is an effective treatment to slow the accelerated decline of lung function in COPD patients. Evidence is accumulating for the clinical efficacy of inhaled long acting bronchodilators (alone or combined with inhaled steroids) and inhaled once daily anticholinergics (tiotropium) though the medications are more expensive. Further studies on lung function and survival are being carried out and the impact of these medications on the clinical course of COPD will be addressed. Pulmonary rehabilitation can achieve significant and clinically meaningful improvements in multiple outcome areas including dyspnoea, exercise ability, health status and healthcare utilisation and should be recommended to COPD patients with moderate or severe disease. Medical practitioners are recommended to refer to the latest guidelines available (www.goldcopd.com) for the advances in COPD management.

Key messages

1. Medical practitioners should aim at early detection of COPD using spirometry and smoking cessation.
2. There are four essential components of management of stable COPD: disease diagnosis and staging, smoking cessation, pharmacological and non-pharmacological therapies and exacerbation management.
3. To achieve optimal disease management, case finding and integrated care by primary and secondary care physicians with introduction of rehabilitation elements is important.

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References