Respiratory Syncytial Virus and Human Metapneumovirus Respiratory Hospitalizations and Outcomes in Colorado Adults ≥50 Years of Age: 2016-2023.

BACKGROUND: Among older adults, respiratory syncytial virus (RSV) infection is a known cause of hospitalization, intensive care unit (ICU) admission, and mortality risk. The severity of the disease burden of human metapneumovirus (HMPV) among older adults is less well recognized. The objective of this study was to better understand risk factors for hospitalization with and outcomes in adults ≥50 years of age infected with HMPV and to compare these with RSV risk factors and outcomes.

METHODS: This was a retrospective cohort analysis of adults 50-88 years of age in 93 medical facilities in the Colorado Hospital Association database between 2016 and 2023. RSV and HMPV, other respiratory infections, and comorbidities were identified using International Classification of Diseases, Tenth Revision codes and grouped by increasing numbers of comorbidities. Multivariate logistic regression was performed to estimate the risk of the various predictors on ICU admission, and mortality for both HMPV and RSV infection, adjusted for sex, age, and comorbidity.

RESULTS: The highest risk for ICU admission was chronic obstructive pulmonary disease (COPD) (RSV: adjusted odds ratio [aOR], 2.24 [95% confidence interval {CI}, 1.81-2.77], P < .001; HMPV: aOR, 2.99 [95% CI, 2.13-4.19], P < .001), and those with neuromuscular disease without dementia (RSV: aOR, 2.33 [95% CI, 1.98-2.75], P < .001; HMPV: aOR, 2.22 [95% CI, 1.75-2.80], P < .001). Age significantly increased the odds of mortality among RSV-infected but not HMPV-infected patients. Neurological disorders with dementia were the highest comorbid risk factor for RSV mortality (aOR, 4.16 [95% CI, 3.01-5.77]; P < .001), in contrast to COPD for HMPV mortality (aOR, 12.44 [95% CI, 3.02-51.17]; P < .001).

CONCLUSIONS: HMPV infection poses a unique disease burden with specific high-risk comorbidities among the older adult population distinct from that of RSV and warrants further study.