RSV and hMPV Illness in the Hospitalized Older Adult Population

Background:

Winter respiratory viruses cause significant morbidity and mortality in the older adult population, with influenza being most frequently recognized.  The burden of illness due to influenza has been well studied, but little is known of the significance of respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) in older adults.  Recent advances in the detection of RSV and hMPV have led to questions regarding their burden in the hospitalized older adult population. 

Objective:

To understand the clinical presentation, patient characteristics, and burden of RSV and hMPV in hospitalized older adults

Methods:

During three consecutive winters, patients 50 years and older admitted to one of four hospitals in Davidson County, TN, with acute respiratory illness (ARI) were evaluated for influenza via throat and nasal swab.  Swabs from subjects agreeing to further sample assessment were tested for RSV and hMPV with reverse-transcriptase polymerase chain reaction (RT-PCR).  Demographic data, symptoms, and co-morbidities were collected at the time of enrollment.  Rates of hospitalization were calculated using weighting by weekly surveillance days, weekly enrollment rates, and hospital market share.

Results:

A total of 1042 patients were eligible for our study and 591 were enrolled.  RSV infection was identified in 31 patients (6.1%), hMPV in 23 patients (4.5%), and influenza in 33 patients (6.5%).  Over the three year period studied, average annual rates of hospitalization were 15.01 (95% CI 8.65, 19.82), 9.82 (95% CI 5.81, 14.41), and 11.81 (95% CI 7.62, 16.18) per 10,000 residents due to RSV, hMPV, and influenza, respectively.  Nearly all patients aged 50 years and older infected with one of the three study viruses had at least one co-morbidity, unlike others admitted with ARI but not found to have one of the three viral infections.  Those with RSV were more likely to complain of sore throat (p = 0.004) and earache (p = 0.048) than those without.  Those infected with hMPV were more likely to be older (p = 0.002) and to complain of cough (p = 0.044) than patients without hMPV, but less likely to have fever than those with one of the other two viruses (p = 0.006).  Those with influenza were more likely to be smokers (p = 0.006) and were less likely to have received influenza vaccination than those with RSV or hMPV (p = 0.023) or patients without influenza (p = 0.02).  Patients having any of the three viruses were more likely to complain of congestion (p = 0.011), sore throat (p = 0.043), cough (p < 0.001), and fever (p = 0.001), than others admitted with ARI. 

Conclusions:

RSV and hMPV result in respiratory viral illnesses that cause significant burdens of disease leading to hospitalization.  Patient populations and presenting symptoms are similar to influenza-associated admissions.  These data suggest that older adults admitted with ARI may harbor a number of respiratory viruses that could be the source of hospital-acquired infections for staff and other patients.