Relationships between pulmonary function and changes in chronic respiratory symptoms. Comparison of Tucson and Cracow longitudinal studies.

Parallel analyses of data from two longitudinal studies, one in Poland and one in the United States, were performed to assess the relationships between pulmonary function and respiratory symptoms. Similar relationships were seen in the both cities using the same methods of analysis. The rate of FEV1 decline and its final level were related to the prior presence of attacks of breathlessness or to a syndrome that also included wheezing and diagnosed asthma. Initial FEV1 level was lower in subjects with dyspnea appearing during the follow-up than in the never-symptom group. These relationships were independent of smoking habits. The consistencies in the parallel analyses strengthen the relationships observed. In Tucson, Ariz, the FEV1 decline in smokers with persistent chronic cough was greater than that due to separate effects of the symptom and smoking. This suggests that chronic cough may be an indicator of an increased effect of tobacco smoke on pulmonary function.