Observations on sputum production in patients with variable airflow obstruction; implications for the diagnosis of asthma and chronic bronchitis.

There are few clinical studies on hypersecretion in asthma, defined as variable airflow obstruction. One hundred and thirty defined asthmatics were questioned in detail about their clinical features, with special reference to sputum production. Other clinical and laboratory data were obtained from the hospital notes. Thirty (23%) denied sputum production at any time. Of the hundred patients reporting sputum, 55 reported the largest volume when an attack of asthma was at its worst and 42 reported most sputum during recovery. Three patients reported unchanging sputum volumes regardless of asthma attacks. There was an association between greater sputum volumes and increased absenteeism due to respiratory symptoms (P less than 0.01) and negative prick skin tests (P less than 0.001). Cigarette smoking and bronchopulmonary aspergillosis were uncommon among our patients, and did not alone account for the sputum production rates. Sixty-eight per cent of patients reported that their pattern or volume of sputum production during attacks had not changed substantially since the onset of their asthma. Patients also fulfilling the Medical Research Council (MRC) criteria for chronic bronchitis (n = 56) were more likely to have smoked than those who did not (P less than 0.005), although 32 (57%) of the asthmatics with chronic bronchitis had smoked little or not at all. Moreover the lability of peak flow measurements was similar in asthmatic patients with and without chronic bronchitis (Lability index 43 and 42% respectively). The prevalence of persistent airflow limitation (PAL) in addition to a variable component related to duration of asthma but not to smoking. The relation between PAL and sputum production was complex.(ABSTRACT TRUNCATED AT 250 WORDS)