Bronchial asthma (asthma for short) and chronic obstructive pulmonary disease (COPD for short) are two different diseases, but in clinical practice it is sometimes not easy to clearly distinguish between asthma and COPD. More complex is the coexistence of asthma and COPD, the so-called asthma-CDD overlap syndrome. It has been found that patients with both asthma and COPD have more frequent exacerbations, poorer quality of life, more rapid decline in lung function, higher mortality rates, and greater medical costs.
The joint guideline proposes a stepwise approach (stepwiseapproach) to the diagnosis and differential diagnosis of asthma, COPD and ACOS, with five steps, including experimental treatment.
Step 1: Does the patient have chronic airway disease?
The first step in diagnosing this type of disease is to identify patients who are at risk or likely to develop chronic airway disease, and to exclude other possible causes of respiratory symptoms. This is based on a detailed history, physical examination, and other tests (e.g., chest x-ray, questionnaires).
In terms of clinical history, features suggestive of chronic airway disease include.
1. chronic or recurrent cough, sputum, dyspnea or wheezing, or recurrent acute lower respiratory tract infections
2. a history of asthma or chronic obstructive pulmonary disease diagnosed by a previous physician
3, history of treatment with inhaled medications.
4. History of smoking.
5. History of occupational hazard exposure.
Step 2: Comprehensive clinical diagnosis (syndromic diagnosis) of asthma, COPD and ACOS in adults.
1. Collect features that support the diagnosis of asthma or slow-onset lung
Features supporting the diagnosis of asthma or LBP can be obtained through careful history taking, including age, symptoms (especially variability in onset and progression, seasonality or periodicity, persistence), past history, social and occupational risk factors including smoking history, previous diagnosis and treatment, and response to treatment.
2. Compare the entries that support the diagnosis of asthma or COPD
If more than one (3) of these features (asthma or LBP) are present, then an accurate diagnosis is highly likely in the absence of features supporting an additional diagnosis. It is important to note that the lack of the above-mentioned features has a low predictive value and does not exclude either asthma or slow-onset lung. For example, a history of allergic reactions increases the likelihood that respiratory symptoms are due to asthma, but is not necessary for a diagnosis of asthma, since nonallergic asthma is the accepted asthma phenotype; and allergic is common in the general population including patients who later develop slow-onset obstructive pulmonary disease. The diagnosis of ACOS should be considered when a patient has a similar number of features of asthma and slow-onset lung.
3. Consider the certainty of the diagnosis of asthma or slow-onset lung, or whether ACOS is suggested by the presence of features of both.
Step 3: Pulmonary function measurement
Pulmonary function measurements may clarify the presence of chronic airflow limitation, but are of limited value in distinguishing asthma with fixed airflow obstruction, slow-onset lung, and ACOS.
The provisional diagnosis made in Step 2 above needs to be reviewed and revised if necessary after pulmonary function and other test results are available. Pulmonary function measured at a single visit is not always definitive for diagnosis, and the results must be considered in the context of the clinical presentation and whether or not treatment is being received. Inhalation of glucocorticoids (ICS) and long-acting beta2 agonists (LABA) can affect pulmonary function measurements, especially if they are not discontinued before or for a short period of time. Therefore, review of pulmonary function is necessary both to help determine the diagnosis and to allow assessment of responsiveness to initial therapy.
Step 4: Start initial treatment
When faced with a diagnosis such as ACOS, in which asthma and COPD have a balanced weighting, the “default position” should be to start treatment based on asthma. This is mainly because ICS has a key role in preventing disability and even death in patients with uncontrolled asthma symptoms; in such patients, even seemingly “mild” symptoms (compared to those of moderate or severe COPD) may indicate a risk of life-threatening exacerbations: 1.
1. A comprehensive clinical evaluation suggests that a diagnosis of asthma or ACOS, or LBP is unlikely, and that the prudent course of action is to initiate treatment for asthma until further testing confirms or rejects this initial diagnosis. It is important to note that LABA should not be used without ICS (so-called LABA monotherapy) if asthma features are present.
2. if a comprehensive clinical assessment suggests chronic obstructive pulmonary disease, appropriate bronchodilators (alone or in combination) should be given for symptomatic treatment, but not ICS alone (i.e. ICS monotherapy).
3. Treatment of ACOS should also include other strategies and recommendations recommended by the guidelines, including cessation of smoking, pulmonary rehabilitation, vaccination, and treatment of comorbidities.
The joint guidelines state that for most patients, initial management of asthma and COPD can be well implemented in the primary care setting. However, both GINA and GOLD suggest provisions for referral when appropriate in the management of patients; this may be particularly important in patients with suspected ACOS.
Step 5: Referral for specialized testing
Referral for specialist advice and further diagnostic evaluation is necessary when a patient presents with
1. persistent symptoms and/or acute exacerbations despite treatment
2. there is diagnostic uncertainty, especially when another diagnosis needs to be ruled out, such as bronchiectasis, post-tubercular scarring, fine bronchitis, pulmonary fibrosis, pulmonary hypertension, cardiovascular disease and other causes of respiratory symptoms
3. Patients with suspected asthma or chronic obstructive pulmonary disease who present with atypical signs or symptoms suggest other pulmonary disease diagnoses. These signs and symptoms include hemoptysis, significant weight loss, night sweats, fever, bronchiectasis, or other signs of structural lung disease. Such conditions should be referred as soon as possible without waiting for experimental treatment of asthma or chronic obstructive pulmonary disease
4. suspected chronic airway disease, but lacking the combined clinical features of asthma and slow-onset lung.
5. the presence of comorbidities that have the potential to interfere with the assessment and management of airway disease
6. problems in the management of asthma, chronic obstructive pulmonary disease and ACOS, which should also be referred.
Obviously, although the medications used for the treatment of ACOS are the same as those used for asthma and chronic obstructive pulmonary disease, the principles are different. For example, for long-term treatment, long-acting bronchodilators (β2 agonists and/or anticholinergics) can be used alone in patients with chronic obstructive pulmonary disease and ICS can be used alone in patients with asthma, but patients with ACOS should, in principle, be treated with a combination of ICS and long-acting bronchodilators.