The Increased Risk for Postinfluenza Pneumonia Among Cystic Fibrosis Carriers-A Population-Based Study

Area of Science:

• Pulmonary Medicine
• Infectious Diseases
• Genetics

Background:

• Influenza infection is a known risk factor for secondary bacterial pneumonia.
• Individuals carrying cystic fibrosis (CF) gene mutations may have altered susceptibility to pulmonary infections.

Purpose of the Study:

• To investigate if cystic fibrosis (CF) carriers have an elevated risk of post-influenza pneumonia compared to non-carriers.

Main Methods:

• A large-scale analysis of insurance claims data (2001-2023) was performed, comparing 38,047 CF carriers with 380,470 matched controls.
• Two analytical approaches were used: individual-level risk assessment for pneumonia post-influenza and a cohort-level analysis of weekly pneumonia incidence adjusted for influenza-like illness.
• Data included Centers for Disease Control and Prevention (CDC)-reported influenza data across multiple seasons.

Main Results:

• CF carriers demonstrated approximately 34% greater odds of developing pneumonia following an influenza diagnosis at the individual level.
• While influenza incidence was not higher in CF carriers, their pneumonia incidence rate was found to be about 55% greater than in the control population.
• These findings were consistent across cohort-level analyses accounting for influenza activity.

Conclusions:

• The CF carrier state is associated with a significantly increased risk of secondary pneumonia following influenza.
• Given the prevalence of CF carriers and influenza, a substantial number of secondary pneumonia cases may be attributed to the CF carrier status.
• These findings underscore the importance of considering CF carrier status in the management and prevention of post-influenza pneumonia.