medwireNews: US researchers say that influenza prevalence can be used to anticipate chronic obstructive pulmonary disease (COPD) admissions and help to reduce the national burden of hospitalizations.
Using the "natural experiment" of the 2009 pre-winter influenza outbreak, the team shows that influenza activity is significantly associated with the incidence of COPD hospitalizations, particularly in older patients.
Philip Polgreen (University of Iowa, Iowa City) and colleagues say, therefore, that "improvements in influenza surveillance, prevention, and treatment could provide significant opportunities to decrease the national burden of hospitalizations of patients with COPD."
They used data from the National Inpatient Sample on hospitalizations with a primary diagnosis of COPD, as well as primary and secondary diagnoses of influenza between January 1998 and July 2010. In October 2009, there was a peak in influenza cases due to the H1N1 strain before the normal flu season, which presented an opportunity to analyze the relationship between flu and COPD admissions without the presence of other confounding seasonal factors.
There were strong, significant correlations between flu incidence and COPD hospitalizations over time, as well as with COPD requiring mechanical ventilation, acute exacerbations of COPD, and acute exacerbations requiring mechanical ventilation.
And, this relationship was particularly strong among patients aged 65 years and over, in whom 4.2% of COPD admissions were attributable to influenza activity compared with 3.7% of admissions in the under 65s. In patients aged over 65 years who needed mechanical ventilation, this attributable fraction rose to 4.9%.
Overall, the authors estimate that, if influenza activity in the peak month of the year could be reduced to baseline, between 3 and 5% of COPD admissions could be avoided, which in the USA would equate to 18,000 to 30,000 prevented admissions.
They also show that incorporating influenza data significantly improved COPD admission prediction over temporal patterns alone, resulting in a 29.9% reduction in mean squares prediction error.
Polgreen and colleagues say the findings highlight the importance of influenza vaccination, which currently falls below both World Health Organization and national targets in the USA.
"Despite guidelines for routine vaccination in patients with COPD, influenza continues to have a significant influence on patient outcomes and healthcare use," they comment in the Journal of Chronic Obstructive Pulmonary Disease.
Additionally, improved influenza surveillance could help target strategies to prevent admission in patients with COPD, as well as to better prepare hospitals in anticipation of admission, they conclude.
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