A significant association between influenza and asthma hospitalizations has been demonstrated at the population level in adult patients in New York City, with the associations varying on the basis of age and geographic locale, according to the results of a longitudinal ecological study that were published in BMJ Open.

Investigators sought to establish whether asthma-related hospitalizations of children and adults in the 5 boroughs of New York City were linked to influenza-related hospitalizations temporally and spatially. They reviewed the Statewide Planning and Research Cooperative System’s records of hospitalizations in Manhattan, the Bronx, Queens, Brooklyn, and Staten Island between 2002 and 2012. All hospitalizations with a primary diagnosis of asthma or influenza were identified. A time-series regression analysis was conducted using aggregate monthly counts of influenza hospitalizations as predictors of asthma hospitalizations.

Time-series analysis of the overall population demonstrated a significant positive association between influenza and asthma hospitalizations (P <.011). When stratification based on age was included in the analysis, a significant positive correlation between asthma and influenza hospitalizations was observed in patients ≥18 years of age (P <.01). In contrast, there was no significant association reported in individuals <18 years of age.

The percentages of excess risk for influenza-related asthma hospitalizations were found to increase with older age, with adults 18 to 44 years of age, 45 to 64 years of age, and ≥65 years of age with excess risk percentages of 2.9%, 3.4%, and 4.0%, respectively. Time-series analysis based on geographic location revealed positive significant associations between asthma and influenza hospitalizations in the boroughs of Brooklyn (P =.03) and Manhattan (P <.01). Individuals residing in Manhattan and Brooklyn had a 2.5% and 1.6%, respectively, percentage of excess risk for influenza-related asthma hospitalizations.

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The investigators concluded that influenza prevention strategies that target adult populations, particularly those patients who live in Manhattan and Brooklyn, have the potential for reducing the number of influenza-related asthma hospitalizations. However, the researchers were unable to account for such environmental factors as humidity, pollution, and temperature, all of which can affect the transmission of influenza, as well as the exacerbation of asthma.


Trinh P, Jung TH, Keene D, Demmer RT, Perzanowski M, Lovasi G. Temporal and spatial associations between influenza and asthma hospitalisations in New York City from 2002 to 2012: a longitudinal ecological study. BMJ Open. 2018;8(9):e020362.