THE INCIDENCE OF RESPIRATORY-TRACT INFECTION IN ADULTS REQUIRING HOSPITALIZATION FOR ASTHMA

Acute respiratory tract infections (RTI) are known to worsen asthma pa rticularly in children. There are few studies in adults assessing the incidence of RTI in patients hospitalized with acute asthma. Aim: To d ocument the incidence of RTI in adults hospitalized with acute asthma. Methods: A prospective study of patients with acute asthma admitted t o the Department of Respiratory Medicine, Western Hospital Footscray, over a 12-month period. A control group was studied from elective surg ical inpatients. Patients were investigated with serologic tests for C hlamydia, Mycoplasma, Legionella, and influenza A and B. Nasopharyngea l aspirate (NPA) samples were cultured for influenza, respiratory sync ytial virus (RSV), adenovirus, parainfluenza, rhinovirus, and herpes s implex virus. If sputum was available, it was assessed with microscopy and culture. Blood cultures were taken if patients were febrile and a ll patients had a chest radiograph. Control subjects completed serolog ic tests and NPA. Results: Seventy-nine patients (33 male and 46 femal e) and 54 control subjects (26 male and 28 female) were studied. Two p atients were enrolled twice. Mean (+/-SD) age of patients was 35+/-15 years (range, 16 to 66 years), and mean age of control subjects was 37 +/-15 years (range, 18 to 69 years). In the patient group, 29 (37%) ha d evidence of recent RTI of which 23 were viral. Five of the control s ubjects (9%) had evidence of recent RTI (p<0.001). Twenty-four patient s were positive on serologic and/or NPA culture. Five patients had pos itive serologic test results and/or NPA culture to two or more agents. Two patients tested positive on sputum, radiograph, and temperature c riteria. Three patients tested positive on the basis of radiographic e vidence of consolidation, blood neutrophilia, and temperature. Influen za A (13) and rhinovirus (9) were the most common infectious agents. O ther agents identified were RSV (one), influenza B (two), adenovirus ( one), and Mycoplasma (one). Influenza and rhinovirus infections occurr ed predominantly in late and early winter, respectively. Summer hospit alization did not relate to RTI. Conclusion: Thirty-seven percent of a dult patients with acute asthma admitted to the Department of Respirat ory Medicine over a 18-month period had evidence of recent RTI.