RESPIRATORY VIRUSES AND EXACERBATIONS OF ASTHMA IN ADULTS

Objective-To study the role of respiratory viruses in exacerbations of asthma in adults. Design-Longitudinal study of 138 adults with asthma . Setting-Leicestershire Health Authority. Subjects-48 men and 90 wome n 19-46 years of age with a mean duration of wheeze of 19.6 years. 75% received regular treatment with bronchodilators; 89% gave a history o f eczema, hay fever, allergic rhinitis, nasal polyps, or allergies; 38 % had been admitted to hospital with asthma. Main outcome measures-Sym ptomatic colds and asthma exacerbations; objective exacerbations of as thma with greater-than-or-equal-to 50 l/min reduction in mean peak exp iratory flow rate when morning and night time readings on days 1-7 aft er onset of symptoms were compared with rates during an asymptomatic c ontrol period; laboratory confirmed respiratory tract infections. Resu lts-Colds were reported in 80% (223/280) of episodes with symptoms of wheeze, chest tightness, or breathlessness, and 89% (223/250) of colds were associated with asthma symptoms. 24% of 115 laboratory confirmed non-bacterial infections were associated with reductions in mean peak expiratory flow rate greater-than-or-equal-to 50 l/min through days 1 -7 and 48% had mean decreases greater-than-or-equal-to 25 l/min. 44% o f episodes with mean decreases in flow rate greater-than-or-equal-to 5 0 l/min were associated with laboratory confirmed infections. Infectio ns with rhinoviruses, coronaviruses OC43 and 229E, influenza B, respir atory syncytial virus, parainfluenza virus, and chlamydia were all ass ociated with objective evidence of an exacerbation of asthma. Conclusi ons-These findings show that asthma symptoms and reductions in peak fl ow are often associated with colds and respiratory viruses; respirator y virus infections commonly cause or are associated with exacerbations of asthma in adults.