REVERSIBLE AIR-FLOW LIMITATION IN ADULTS WITH RESPIRATORY-INFECTION

The aim of the study was to determine the occurrence of airflow limitation and the frequency of significant reversibility in respiratory infections in adults without known asthma or chronic obstructive pulmonary disease (COPD). We also wanted to study the association between airflow limitation and aetiological agents diagnosed by serological analyses. Spirometry was performed in 574 adult general practice patients with upper or lower respiratory tract infection, and follow-up measurement was obtained in 429 of them. In the latter group, we also obtained paired sera for analysis of antibodies against respiratory viruses, chlamydial and mycoplasmal agents. Median forced expiratory volume in one second (FEV1) in all patients included was 90% of predicted; significantly lower in patients with an established diagnosis of asthma or COPD, compared to those without, 77 and 91% predicted, respectively. Among the patients without known asthma or COPD there was a strong association between low FEV1 and the symptoms cough and dyspnoea. Both acute-phase and follow-up FEV1 was measured in 395 of the patients without known asthma or COPD, and a significant increase in median value from 92 to 96% was registered. A reversibility of FEV1 of >15% was measured in 23% of the 395 patients, uninfluenced by anti-asthma treatment in the great majority. Patients with an established viral, mycoplasmal or chlamydial infection had a significantly lower FEV1 at entry and a greater reversibility, compared to those without such aetiological diagnosis. We conclude that reversible obstruction was particularly common in the patients diagnosed as having acute bronchitis, but that it was also found in the patients diagnosed as having upper respiratory tract infection. The high frequency of spontaneous reversibility in otherwise healthy adults calls for caution when response to anti-asthma treatment is interpreted in patients with possible asthma.