Endocardftis Is Cardiac Catheterization Usually Needed Before Cardiac Surgery ?

EditorIals authors state that they think the increase in responsiveness observed in their patients was simply the result of cigarette smoking, but they do not examine this question. Thus, the origin of the increase in responsiveness and its relationship to atopy and cigarette smoking are not clarified by their investigation. The major problem with all existing longitudinal work published on increased responsiveness is that only subjects who already have COLD have been examined. At best, the Barter and Campbell and Kanner data can identify increased levels of responsiveness as a correlate of disease. At worst, their findings may simply be the result of selection bias. Although it is important to know that those subjects with COLD who have increased levels of airways responsiveness will fare poorly, a far more important question is whether one can identify the causes of increased levels ofresponsiveness, and its relationship to other putative risk factors, and whether such responsiveness is an independent risk factor fir the development of COLD. This is a central question in adult COLD epidemiology at the present time fir two reasons. First, if smoking causes increased levels of airways responsiveness, this will provide important insight into the pathogenesis of COLD. Secondly, it may target a group of subjects at high risk in whom therapeutic trials of bronchodilators might be used to attempt to intervene in the disease process. To determine whether increased level of airways responsiveness is a risk factor fir COLD, one would have to fillow prospectively a large cohort of subjects randomly selected from a community, some of whom smoked and some ofwhom did not, and assess respiratory symptoms, atopy, airways responsiveness and pulmonary function longitudinally over several years. Whether existing data are currently available with sufficient power to answer this question, or whether new studies carried out over several years will be required, the issue is of enough importance that a variety of methodologic approaches should be considered. Scott T Weiss, M.D., F.C.C.P; and Frank E. Speizer, M.D. Boston 4 FishJE, Mankes HA. Airway reactivity: role in acute and chronic disease. Current Pulmonology 1984; 5:169-99 5 Lorber DB, Kattenborn W, Burrows B. Response to isoproterenolin a general population sample. Am Rev Respir Dis 1978; 118:855-61 6 Pride NB, Taylor RG, Joyce H, Gross E, Holland F Relation between bronchial reactivity to inhaled histamine and annual decline in FEV,, in male smokers and ex-smokers. 1984; 85