Introductory Chapter: Contemporizing Chronic Obstructive Pulmonary Disease

Abstract

Chronic Obstructive Pulmonary Disease (COPD) is a medical condition with a long and varied history. Centuries prior to the establishment of the term COPD in the late 1950s, the sub-components of ‘pulmonary emphysema’ and ‘chronic bronchitis’ have already been described in medical literature. The term COPD has been increasingly accepted and used by both healthcare institutions and the wider public since its inception, especially when compared to the usage of one of its primary components, ‘emphysema’. As such the recently proposed and adopted changes to the definition, nomenclature and taxonomy (classification) of COPD by the Global Strategy for Prevention, Diagnosis and Management of COPD is of prime interest as they denote significant amendments to the decades-long understanding of COPD. This book chapter summarizes the rationale behind the recent revisions of the basic conceptions of COPD and discusses the implications of these contemporizing changes for clinicians and researchers.

1. Introduction

One characteristic of modernity is the belief that the more recent something is, the better and truer it must be. Chronocentrism, the assumption that the current time-period represents the best epoch throughout history, pervades societies of any age, but perhaps, such conceit affects this generation more than previous ones. With the onset of the Information Age, when new data can be proclaimed and widely assessed almost instantly, the hubris of living in the Golden Age of knowledge transfer and consensus creation is considerable. Nonetheless, readers of honorable vintage will recall certain promising discoveries in the past that did not stand the test of time, and likewise, established opinions that did not end up ‘on the right side of history.’ A medical condition with such a long history as Chronic Obstructive Pulmonary Disease (COPD) is expectedly fraught with controversies and swings in paradigms. The age-old tussle between an overlap or a continuum of asthma and COPD, and the recent publication followed by dissolution of global guidelines in managing asthma-COPD overlap are some examples of vagaries in current considerations of airway disorders. Of more contemporary interest are the recently proposed and adopted changes to the definition and taxonomy (classification) of COPD itself [1]. This chapter summarizes the recent revisions in the definition, terminology and taxonomy of COPD and proposes a theoretical viewpoint to make sense of contemporizing changes made to the essential notions of this ancient disease.

2. The transforming nosology of COPD and pulmonary emphysema

The terms “emphysema” or “pulmonary emphysema” predated COPD by decades. Bonet’s description of “voluminous lungs” was written in 1679 [2]. In 1821, Laënnec, a clinician, pathologist and the inventor of the stethoscope, first designated the term “emphysema” to the findings of lungs that remained hyperinflated and did not empty well at autopsy. The first comprehensive textbook of pulmonary emphysema was published in 1956. During the period 1959–1962, the components of COPD – chronic bronchitis, emphysema and asthma were defined by colloquium. Over the intervening years till present, the clinical definition of COPD has been refined as emphysema continues to retain its description in anatomic terms.

The Global Strategy for Prevention, Diagnosis and Management of COPD, first issued about a quarter of a century ago, has recently revised its definition of COPD [3]. In its latest iteration, COPD is defined as “a heterogeneous lung condition characterized by chronic respiratory symptoms (dyspnea, cough, expectoration) due to persistent abnormalities of the air ways (bronchitis, bronchiolitis), and/or alveoli (emphysema), that cause persistent, often progressive airflow obstruction”. This new statement no longer requires the presence of demonstrable airflow limitation for defining COPD nor limits its causation to inhalation of noxious agents, viz., cigarette smoking. In addition, newer ‘classes’ of COPD reflecting underlying causes (“etiotypes”) are included in a new taxonomy. These “etiotypes” are: genetically determined COPD, COPD due to abnormal lung development, environmental COPD, COPD caused by infections, COPD and asthma, and idiopathic COPD. In particular, the recently revised Global Strategy also emphasizes that COPD results from gene (G)- environment (E) interactions that occur over the lifetime (T) of an individual (ingeniously termed “GETomics”). The prime motivation behind these changes is the reduction of the obdurate morbidity and mortality in COPD, a process thought to be currently vitiated by delayed diagnosis resulting from a parochial definition and limited consideration accorded to pathogenetic factors. The effort to transform the basic tenets of COPD for the improvement of outcomes is laudable, as latest estimates of COPD disease burden (both current and future) are deplorable [4], especially when viewed against progress made for other major non-communicable diseases.

The most contentious among the recent revisions is the introduction of the following new terms – early COPD, mild COPD, young COPD, pre-COPD. These may lead to confusion rather than clarification, even though not all these newly defined entities are encouraged for use in clinical parlance, but in research settings only. Another novel term PRISm (preserved ratio impaired spirometry) describes findings of preserved FEV1/FVC ratio ≥ 0.7 but impaired spirometry (FEV1 < 80% predicted), both indices after bronchodilation, is more likely to be utilized as it is a distinct and objectively defined entity.

It is noteworthy that, together with the revision in definition of COPD, the decades-long necessity for spirometry in the diagnosis of COPD has been removed from the new global guidelines [3]. In other words, spirometry is now desirable, but no longer “required” for diagnosing COPD, much like the case for bronchial asthma. This is in line with the goal to include disease in its early stages, before airflow obstruction is evident. However, the trade-offs for such inclusivity are the uncertainty of COPD diagnosis and the mislabeling of cases. Regarding these concerns, the researchers advising these recent revisions had argued that a nosologic entity such as COPD defined only in clinical-descriptive terms is valid, “provided that verbal usages are made explicit and applied consistently” [1]. It remains to be seen how well patients take to being diagnosed with COPD and classified accordingly in their “earlier” stages without any objective operational criteria.

Gratefully, amidst the recent wide-ranging nosologic changes, the term COPD is retained. The acronym COPD has taken decades for widespread acceptance among stake-holders and the wider public. COPD is now recognized by major global health organizations, widely used in the medical literature, and accepted in the Internal Coding of Diseases. Based on Google Trends, ‘COPD’ is an increasingly popular search term since the year 2004, especially compared to ‘emphysema’ (see Figure 1). The rising awareness and usage of the term COPD may presumably be credited to the foregoing annually-revised Global Strategy on COPD and other efforts by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), which was established in 1999. Common sense has prevailed in maintaining this medical term (although not a most precise one) for which some educators have spent the length of a career in health communication.

Figure 1.

Time plot using Google Trends showing frequency of search terms over time since 2004.

3. The prejudice of the universal

The recent revisions to the definition and nomenclature of COPD may be compared to another common predilection of modernity - a dichotomy between the universal and the particular. Moderns have been conditioned to value the universal and the abstract over the situated and the specific. This prejudice of the universal over the particular is expressed in the need for an all-encompassing definition of a condition as common and as heterogeneous as COPD. Yet, the more inclusive and general a definition has become, the greater the need for classification and sub-typing according to etiology and time of presentation, as we are presently witnessing. The complexity involved in diagnosing and treating a widespread and varied malady such as COPD requires contextualization as concepts of COPD vary according to global/local and synchronic/diachronic factors as previously described [5]. Recognizing the prejudice of the universal, it behooves clinicians to desist the devaluing of specific patient differences, even if it is deemed ‘scandalous’ to emphasize such differences beyond general characteristics of the disease.

4. Conclusion

The recent amendments to the definition and nomenclature of COPD represent broad changes to global guidelines that have been established for many years. These changes to the basic concepts and requirements in the diagnosis of COPD have major implications in research and clinical practice. Only time will tell if these revisions correspond to the unexamined modern notion of “the newer, the better”.

Conflict of interest

The authors declare no conflict of interest.