Evaluating symptoms is a central part of the chronic obstructive pulmonary disease (COPD) assessment system as suggested by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Considering the pros and cons of all currently available tests, GOLD suggests using primarily the modified Medical Research Council dyspnea scale or the COPD Assessment Test. Based on the test results, patients are categorized as having a low or high level of symptoms. This level then becomes one of the 2 dimensions of the ABCD grading system, which was designed to match the best initial treatment option to the individual patient’s needs.
Symptoms are key drivers to consider the diagnosis of chronic obstructive pulmonary disease (COPD).
Assessment of symptoms together with exacerbation history is the basis of treatment decisions.
Symptoms can be evaluated by the use of dyspnea scores, health status questionnaires, and multidimensional scoring systems.
According to the Global Obstructive Lung Disease recommendations, the modified Medical Research Council Score and the COPD Assessment Test are the preferred choice to evaluate the presence and significance of symptoms.
Chronic obstructive pulmonary disease (COPD) is a chronic disease whereby symptoms are the main driver for patients to seek medical attention. The symptoms can be multifaceted and range from subtle to very severe. In fact, many patients are diagnosed while they experience the first exacerbation, when for the first time, the patient may report dyspnea as the predominant symptom causing his medical problem. Cough or phlegm production may also accompany dyspnea as an important health problem, but patients usually consider these symptoms natural consequences of smoking or working in polluted environments, being reported by up to 30% of patients. Fatigue, weight loss, and anorexia may be observed in more severe forms of the disease. , Symptoms may vary from day to day, at different times of the day, and may precede the development of airflow limitation. They impact physical activity and health status, and severe dyspnea has a similar impact on the time to hospitalization and risk of death as frequent COPD exacerbations have. It follows that identification and quantification of dyspnea is an important element in the medical history of any persons suspected of having a respiratory disease.
As stated in the Global Obstructive Lung Disease (GOLD) document, COPD should be considered in any patient with respiratory symptoms and/or a history of exposure to risk factors. Although a spirometry showing airflow limitation is required to confirm the diagnosis of COPD, symptoms and risk factors may be present without significant airflow limitation. Interestingly, those individuals may be receiving long-term treatment with respiratory medications and report events that are rated as exacerbations, and some may show structural lung changes on chest imaging (emphysema, gas trapping, airway wall thickening) , with “normal” spirometric values. In these individuals, the detection of dyspnea, cough, and/or sputum increases the risk of future development of airflow limitation; however, its management remains unknown, but it is reasonable to emphasize preventive measures. Particularly important is the issue that dyspnea itself is not a specific symptom of COPD. Relevant differential diagnoses like heart failure may be associated with similar complaints. In addition, patients with COPD frequently exhibit comorbidities that may modify and/or amplify the respiratory symptoms the identification of which and their management will improve the outcome of those patients.
Assessment of symptoms
The “ABCD” assessment tool of the 2011 GOLD update was a major step forward from the simple spirometric grading system of the earlier versions of GOLD because it incorporated patient-reported outcomes and highlighted the importance of exacerbation prevention in the management of COPD. The current GOLD assessment highlights the importance of symptoms and exacerbation risk in guiding therapies, reinforcing the concept that symptom quantification is of high importance in patients suspected or diagnosed as suffering from COPD.
Therefore, it may be preferable not to just ask the patient the generic question of “how are you doing,” but also to use a more formalized approach. Generally speaking, there are 3 methods currently used in symptom quantification: scoring the intensity of dyspnea, evaluating health status, and finally, using multidimensional scoring systems. Table 1 summarizes some of the features of currently used tests, all of which have been reviewed in detail by Glaab and colleagues.
|SF-36||Generic||Physical and social function, mental health, energy/vitality, health perception, physical and mental role limitation, pain||36||Self-administered|
|SGRQ||Disease-specific||Symptoms, activities, psychosocial impact||50||Self-administered|
|CRQ||Disease-specific||Dyspnea, emotional function, fatigue, mastery||20||Interview|
|CCQ||Disease-specific||Symptoms, functional state, mental state||10||Self-administered|
All scales mentioned rely on the basic presumption that there exists a generally valid minimal important difference (MID) that is suitable for categorization independent of the individual patient’s status. However, the authors would like to point out that this conceptualization is based on the hypothesis that differences are linear, whereas most biological systems appear to have nonlinear relationships. Moreover, there is some disagreement in the literature regarding the MIDs for certain scales. In addition, the published data addressing the use of these scales represent group comparison. Thus, the reported changes of scores show that they are responsive on a group level, whereas in clinical practice the authors are looking for an assessment tool that allows individual comparisons.
Assessment of dyspnea
Baseline Dyspnea Index/Transition Dyspnea Index
The Baseline Dyspnea Index and Transition Dyspnea Index (BDI/TDI) were designed to measure multiple dimensions of breathlessness (functional impairment, magnitude of task, and magnitude of effort) in relation to the level of activity. Symptoms are evaluated at a specific time point (usually baseline, BDI), and the change over time (TDI) is quantified. In the original version, BDI and TDI are obtained during an interview by an experienced observer with open-ended questions regarding breathlessness during everyday activities. If the patient’s recall of the baseline state (BDI) is limited, the measured change is not reliable (recall bias).
A self-administered computerized (SAC) version of the BDI/TDI has been developed to remove any interviewer bias and to provide direct patient-reported ratings of dyspnea. The SAC BDI/TDI has already been used in clinical trials, and an MID has been derived (1 unit difference between BDI and TDI), but this was mainly based on retrospective analyses of published data.
The CR-10 or Borg scale has been designed to measure exertional dyspnea in COPD patients. , The 10-point category ratio scale is easy to use. Nevertheless, detailed instructions are mandatory. Based on retrospective analysis, an MID for the Borg scale in the range of 1 unit has been suggested. It has widely been used in studies evaluating the effect of interventions on exercise endurance using constant load cardiopulmonary exercise testing.
Medical Research Council or Modified Medical Research Council Scale
The MRC scale was developed as a simple and standardized method to quantify dyspnea in relation to a function in COPD patients. It is a 5-point scale whereby the patient is asked about dyspnea in relation to a specific level of activity. A modified version of this scale is used today (mMRC), which has simplified statements, such as “people” instead of “men.” The grade of dyspnea is given from 1 to 5 (MRC) or 0 to 4 (mMRC). An MID has not been established, but 1 study has shown an increased risk of death for each unit increase in the scale. The method has been used in clinical studies , and in clinical practice primarily in many countries. Avoidance of exercise may induce underestimation of dyspnea (underestimation bias). The MRC and mMRC are considered to be relatively insensitive to changes, for example, following interventions, , and its validation has been based on relatively few clinical studies.
Assessment of health status
Although quality of life is a unique feature of a specific individual, health status represents a standardized quantification of the impact of a disease. Health status is assessed using questionnaires.
Medical Outcomes Study Short Form-36
The medical outcomes study short form-36 (SF-36) is not a disease-specific, but a generic health survey. It is designed for self-assessment of psychic, physical, and social features. Although it has 36 items, it is easy to use. The SF-36 seems to be less responsive than COPD-specific instruments.
St. George’s Respiratory Questionnaire
The St. George’s respiratory questionnaire (SGRQ) was developed to analyze health status in patients with respiratory disease, for example, COPD or asthma. Later, a COPD-specific version was published. The SGRQ has 3 domains: symptoms (frequency and severity), activity (effects on and adjustment of everyday activities), and psychosocial impact. The total score has a maximum of 100 points, with values ranging from 0 to 100. The higher the number, the more impact the disease has. The MID has been thought to be 4 points.
The SGRQ represents the standard method for evaluation of health status in clinical trials. Nevertheless, it has some limitations: nonpole questions may induce a trend bias (first possible answer is usually “yes” and indicates worse health status). Besides, a missing answer is processed as if the patient had answered “no.” SGRQ scores are not independent of sex, age, education, and comorbidities. Finally, the SGRQ has 50 items. Therefore, it is not feasible to be used in daily clinical practice.
Chronic Respiratory Disease Questionnaire
The chronic respiratory disease questionnaire (CRQ) evaluates physical-functional and emotional limitations owing to chronic lung diseases like COPD. It covers dyspnea, fatigue, emotion, and mastery. The patient is asked to recall the 5 most important activities that caused breathlessness over the past 2 weeks. An MID of 0.5 has been calculated. Because of its design that is based on individual assessment, it is not interchangeable with other disease-specific instruments.
Clinical Chronic Obstructive Pulmonary Disease Questionnaire
The clinical COPD questionnaire (CCQ) was developed to measure symptoms and the functional state in daily clinical practice. It is self-administered, has 10 items, and covers 3 domains (symptoms, functional, and mental state). It has been validated and is considered to be responsive to changes of the patient’s situation. An MID of 0.4 was calculated.
Chronic obstructive pulmonary disease assessment test
The COPD Assessment Test (CAT) was developed to measure symptoms and functional state in daily life. , Besides, it may also be informative regarding comorbidities. It is self-administered and contains 8 items. The CAT is validated, available in many languages, and easy to use. It has been shown to be responsive to rehabilitation and exacerbations. A good correlation between CAT and SGRQ has been reported. Based on 1 study, CAT and CCQ have similar psychometric properties and are both valid and reliable questionnaires to assess health status in COPD patients. The MID is 2 points.
Multidimensional scoring systems
There are several multidimensional scoring systems available, for example, ADO (age, dyspnea, obstruction), DOSE (dyspnea, obstruction, smoking, exacerbations), and body mass index, obstruction, dyspnea, and exercise capacity (BODE).
The BODE index is so far the only multidimensional scoring system that has gained broader acceptance. It was developed as a prognostic marker for COPD. Included are nutritional state ( B ody mass index), airflow limitation ( O bstruction; forced expiratory volume in 1 second, FEV 1 ), breathlessness (mMRC D yspnea scale), and E xercise capacity (distance walked in 6 minutes). The BODE index has been used in interventional studies investigating effects of lung volume reduction surgery, pulmonary rehabilitation, and physical training. The BODE index integrates subjective and objective measurements, including evaluation of exercise capacity. Its prognostic power to predict mortality and exacerbations in severe to very severe COPD is superior to the individual components.
The BODE index has been optimized to predict 1-year mortality. Parameters that determine long-term survival may differ from those that predict shorter-term survival. Besides, the focus was on patients with severe and very severe airflow limitation. Thus, its validity in patients with less severe disease needs to be established. Finally, the measurement of the 6-minute walking distance requires a certain infrastructure that is not readily available in many clinics.
Considering the pros and cons of all mentioned ways to assess symptoms, GOLD recommends primarily the mMRC and the CAT because of its practical implications. Some of the features in both scores are shown in Table 2 .