Unexpectedly Higher Morbidity and Mortality of Hospitalized Elderly Patients Associated with Rhinovirus Compared with Influenza Virus Respiratory Tract Infection

Rhinovirus is a common cause of upper and lower respiratory tract infections in adults, especially among the elderly and immunocompromised. Nevertheless, its clinical characteristics and mortality risks have not been well described. A retrospective analysis on a prospective cohort was conducted in a single teaching hospital center over a one-year period. We compared adult patients hospitalized for pneumonia caused by rhinovirus infection with those hospitalized for influenza infection during the same period. All recruited patients were followed up for at least 3 months up to 15 months. Independent risk factors associated with mortality for rhinovirus infection were identified. Between 1 March 2014 and 28 February 2015, a total of 1946 patients were consecutively included for analysis. Of these, 728 patients were hospitalized for rhinovirus infection and 1218 patients were hospitalized for influenza infection. Significantly more rhinovirus patients were elderly home residents and had chronic lung diseases (p < 0.001), whereas more influenza patients had previous stroke (p = 0.02); otherwise, there were no differences in the Charlson comorbidity indexes between the two groups. More patients in the rhinovirus group developed pneumonia complications (p = 0.03), required oxygen therapy, and had a longer hospitalization period (p < 0.001), whereas more patients in the influenza virus group presented with fever (p < 0.001) and upper respiratory tract symptoms of cough and sore throat (p < 0.001), and developed cardiovascular complications (p < 0.001). The 30-day (p < 0.05), 90-day (p < 0.01), and 1-year (p < 0.01) mortality rate was significantly higher in the rhinovirus group than the influenza virus group. Intensive care unit admission (odds ratio (OR): 9.56; 95% confidence interval (C.I.) 2.17-42.18), elderly home residents (OR: 2.60; 95% C.I. 1.56-4.33), requirement of oxygen therapy during hospitalization (OR: 2.62; 95% C.I. 1.62-4.24), and hemoglobin level <13.3 g/dL upon admission (OR: 2.43; 95% C.I. 1.16-5.12) were independent risk factors associated with 1-year mortality in patients hospitalized for rhinovirus infection. Rhinovirus infection in the adults was associated with significantly higher mortality and longer hospitalization when compared with influenza virus infection. Institutionalized older adults were particularly at risk. More stringent infection control among health care workers in elderly homes could lower the infection rate before an effective vaccine and antiviral become available.