Patient outcomes after influenza, RSV, or SARS-CoV-2 hospitalization

A recent study posted to the medRxiv* preprint server investigated the elements that predicted all-cause mortality among individuals hospitalized due to influenza, respiratory syncytial virus (RSV), or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Various studies have highlighted risk factors that render specific populations susceptible to severe coronavirus disease 2019 (COVID-19). Therefore, knowledge of the high-risk factors that can exacerbate disease severity from respiratory viruses can help design proactive clinical approaches in the healthcare setting.

Study: Predictors of all-cause mortality among patients hospitalized with influenza, respiratory syncytial virus, or SARS-CoV-2. Image Credit: Red-Diamond / Shutterstock

About the study

The researchers of the present observational study identified the direction and extent of shared and divergent factors used for the prediction of 30-day all-cause mortality after patient hospitalization with RSV, influenza, or SARS-CoV-2.

The team collected population-based clinical and health administrative data from Ontario, Canada, about patients hospitalized with RSV, influenza, and SARS-CoV-2. Three study cohorts were generated to examine the predictors of severe disease outcomes among patients hospitalized with the three infections. The primary outcome of interest in the present study was the 30-day all-cause mortality reported after the hospitalization of a patient suffering from influenza, RSV, or SARS-CoV-2.

Influenza-related hospitalizations were the ones where the patient’s discharge abstract included any of the following International Classification of Diseases (ICD)-10 codes: J09, J10.0, J10.1, J10.8, J11.0, J11.1, or J11.8. Patients were considered RSV-hospitalized if their discharge abstract had any of these ICD-10 codes: J12.1, J20.5, J21.0, or B97.4. Patients were considered SARS-CoV-2-hospitalized if 1) they were reported as hospitalized in the discharge abstract database (DAD) and were polymerase chain reaction (PCR)-positive for SARS-CoV-2 infection 14 days prior or three days after hospitalization or 2) they were documented as hospitalized in the case and contact management (CCM) system.

Among hospitalizations related to influenza or RSV, only the first case of hospital admission of the season was eligible for the study. On the other hand, SARS-CoV-2-related hospitalizations included any hospital admission that proved fatal to the patient within 30 days of hospitalization or the first hospital admission if none of the other admissions resulted in 30-day mortality.

The team considered relevant comorbidities like chronic obstructive pulmonary disease (COPD), asthma, cardiac ischemic disease, hypertension, congestive heart failure, dementia, stroke, advanced liver disease, chronic kidney disease, and immunosuppression.

Results      

The present study included 45,749 influenza, 24,345 RSV, and 8,988 SARS-CoV-2 hospitalizations. The median age of RSV-hospitalized patients was lesser than that of patients hospitalized with SARS-CoV-2 and influenza. Among these, almost 47% of RSV-infected patients reported at least one underlying comorbidity, while approximately 84% of influenza patients and 82% of SARS-CoV-2 patients presented several comorbidities.

The crude mortality rate was 20.9% for SARS-CoV-2, 7.0% for influenza, and 2.9% for RSV hospitalized patients. Also, common predictors of disease mortality included factors like older age, residence in a long-term care home (LTCH), vaccination against seasonal influenza, cardiac ischemic disease, congestive heart failure, COPD, hypertension, diabetes, dementia, stroke, and chronic kidney disease. The team also observed a more significant correlation between older age and mortality rates among patients hospitalized with SARS-CoV-2 than among influenza or RSV hospitalized patients. Notably, the other shared predictors of mortality showed more significant magnitudes of association for RSV-hospitalized patients.

A substantial correlation between rural residence and 30-day all-cause mortality was observed among patients hospitalized with SARS-CoV-2 and RSV, while the same was not apparent for patients hospitalized with influenza. Furthermore, immunization of a patient against seasonal influenza provided significant protection against 30-day all-cause mortality among hospitalizations related to influenza but not for patients hospitalized with SARS-CoV-2 and RSV. The team also found a remarkable association of comorbidities like cardiac ischemic disease, congestive heart failure, dementia, and immunosuppression with all-cause mortality among patients hospitalized for influenza and RSV but not among patients hospitalized for SARS-CoV-2.

Conclusion

The study findings highlighted that the extent of association between older age and 30-day all-cause mortality was the highest among patients hospitalized for SARS-CoV-2, indicating that age is a critical predictor of disease severity among COVID-19-infected patients. This factor should be utilized to develop targeted COVID-19 therapeutics.

The researchers believe that future studies would benefit from comparisons drawn between predictors of mortality among patients hospitalized with RSV, influenza, or SARS-CoV-2 variants. Moreover, the knowledge of shared predictors of mortality could help accurately identify patients at the greatest risk of contracting syndromic illnesses from respiratory viruses and predict local resource needs.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.