Author's Response.

Sir,

The editorial referred to by Dr. Varudkar was a comment on the evolution of the test of reversibility over the years and the current understanding of its applications as well as limitations.[1] Evidence has accumulated that shows a limited utility for this test in differentiating asthma from Chronic obstructive pulmonary disease (COPD), and for predicting response to pharmacotherapy. Further, it was emphasized that the diagnosis and classification of severity of COPD is based on post-bronchodilator spirometry.

An editorial is a focused commentary on an issue of importance in research or clinical practice. Dr. Varudkar has raised a number of issues none of which relates to the subject of the editorial.[2] These are more in the nature of general observations and suggestions on different aspects of obstructive airways diseases. However, as these have been raised with reference to the above editorial, a point-wise response is provided below.

Dr. Varudkar has suggested that there should be a list of diseases producing airway obstruction and reversibility to various medications. It is well-known that several lung diseases, besides asthma and COPD, produce airways obstruction on spirometry and have variable degrees of reversibility. These diseases are diagnosed based on their clinical and radiological characteristics. Any standard textbook of pulmonary medicine will provide such a list and it was not the subject matter of the editorial.

It is a standard practice in the management of asthma to identify any allergic component and manage it with avoidance, pharmacotherapy, and immunotherapy as and when indicated. The issue is not relevant as far as reversibility of airways obstruction is concerned. The limitations of the reversibility test apply to asthma irrespective of the presence or absence of allergy.

Over the years, a consensus has developed on how asthma and COPD are defined and guidelines for the management of these diseases describe the criteria for diagnosis besides providing definitions.[34] The last word in medicine is never written and no doubt the definitions and criteria will continue to evolve as newer diagnostic tools of molecular biology will become available in the future.

Dr. Varudkar has suggested that some instrument should be developed to assess the proportions of chronic bronchitis, emphysema, and asthma in a patient. No doubt overlaps exist in presentations and it can be difficult to differentiate in a particular patient. However, COPD and asthma differ in etiology, pathogenesis, pathology, therapeutic approaches and options, complications and in natural history and are regarded as distinct diseases. Within COPD, the extent of emphysema can be evaluated by tests of gas exchange and high resolution computed tomography. COPD and asthma are clinical diagnosis and the results of the reversibility test should not change that clinical diagnosis. A need for such an instrument has not been felt.

In final, I assure Dr. Varudkar that the above editorial has referred to our own original research work.[56] The statement that “we see only blind following of westerner's concepts” is without any basis as a search on the PubMed will show.