Abstract & Commentary
Synopsis: Among patients being evaluated for chronic cough, women are more sensitive than men to inhalation of tussive agents.
Source: Kastelik JA, et al. Am J Respir Crit Care Med. 2002;166:961-964.
This was a carefully controlled study of 118 (68 women) patients who attended a Cough Clinic in Cottingham, England. Their mean age was about 57 years, they had complained of cough for about 2 years, and only 14 were current smokers (we have no data on "ever smokers," but pulmonary function was normal for the group as a whole). They were asked to inhale increasingly concentrated nebulized doses of either capsaicin or citric acid, and cough sensitivity was measured as the dose that caused 2 coughs and 5 coughs per 1-second inhalation (this is apparently standard methodology). Women coughed at much lower doses of either agent than did men. Cigarette smoking, whether the cough was "wet" or "dry," and menopausal state (of women) did not appear to influence cough sensitivity. In general, age and spirometric values were also unrelated to cough sensitivity. Because they used single-breath dosimeter-controlled challenge technique, Kastelik and associates do not believe that difference in subject size explains the difference they found. They conclude that these findings ". . . may explain why female patients predominate in cough clinics."
Comment by Barbara A. Phillips, MD, MSPH
Chronic cough is one of the most vexing problems faced in primary care and in pulmonary subspecialty clinics. Cough symptoms are hard to manage, being highly dependent on patient perception, and notoriously refractory to treatment. For an excellent review of the evaluation of chronic cough, see Irwin and Madison’s report.1 The most common causes of troublesome chronic cough are post-nasal drip syndrome, asthma, and gastroesophageal reflux disease. Irwin and Madison point out among the common pitfalls in management of chronic cough are failure to recognize that postnasal drip, asthma, and GERD can present as cough, assuming that all H1 antagonists are the same, failing to recognize that inhaled medications may sometimes exacerbate cough, assuming that a positive methacholine challenge alone is diagnostic of cough, and failing to recognize that it may take 2-3 months of intensive medical therapy before cough starts to improve.
Asthma is probably more common in women than in men, which could account for some of the disparity in the numbers of patients presenting for care of chronic cough. Further, women are more likely to seek medical care for almost any condition than are men (one of the reasons we live longer!). But the current article is important because it indicates that women are more sensitive to cough stimulation from at least 2 different irritants than men are. In other words, it’s not "all in their heads." (Some of it is probably in their airways).
Dr. Phillips, University of Kentucky; Director, Sleep Disorders Center, Samaritan Hospital, Lexington, KY, is Associate Editor of Internal Medicine Alert.
1. Irwin RS, Madison JM. N Engl J Med. 2000;343:1715-1721.