Methods: Annual hospitalization rates for RSV disease in adults 20 years and older were estimated using weighted counts from the National Inpatient Sample (NIS), a nationally representative database, and denominators from US Census data. RSV hospitalizations were identified by ICD9 codes. Patients were classified as immunocompromised or not based on an existing algorithm. Hospitalizations were characterized by diagnostic codes and severity indicators. Poisson and linear regression were used to test statistical significance of trends.
Results: 28,237 RSV hospitalizations were identified, with 34% classified as immunocompromised. RSV hospitalizations were more often 60 and older (58%), female (57%), and non-Hispanic white (61%). RSV was most often diagnosed in urban teaching hospitals (73.0%) and large hospitals (71.9%). The rate of all adult RSV hospitalizations increased from 0.27 to 1.93 per 100,000 per year over the 15-year period. RSV rates significantly increased for all age groups (p<0.0001), with the largest increase among those 60 and older, rising from 0.5 to 4.6 per 100,000 between 1997 and 2012. Yearly rates for ‘pneumonia, virus unspecified’ decreased for all ages, significantly for those 60 and older, which decreased from 14.2 to 7.0 per 100,000 (p<0.0001). Severity indicators in RSV patients are similar or more severe than for hospitalizations attributed to influenza.
Conclusion: RSV-coded hospitalization rates in adults increased between 1997 and 2012. While there may be some true increase in incidence, the patterns strongly suggest an increase in recognition (and diagnosis) of RSV as an important cause of disease in older adults. RSV disease deserves attention as a potentially severe cause of hospitalizations due to respiratory disease in adults, and the burden likely continues to be underestimated due to underdiagnosis.
J. E. Coalson, AstraZeneca: Collaborator and Consultant , Consulting fee
X. Jiang, AstraZeneca: Collaborator and Consultant , Consulting fee
T. Villafana, AstraZeneca: Employee , Salary
J. P. Fryzek, AstraZeneca: Collaborator and Consultant , Consulting fee
C. S. Ambrose, AstraZeneca: Employee , Salary
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