Influenza-Related Hospitalizations and Associated Comorbidities in Nebraska: 2007-2011

Abstract

Objective: Influenza afflicts approximately 5% -20% of the US population annually. Although prevalence statistics are useful, they are insufficient to understand completely influenza on a health care system. This study estimated Nebraska's annual hospitalization and comorbidity rates due to influenza from 2007 to 2011. Methods: Influenza was defined according to ICD-9-CM primary codes beginning with 487 or 488 in hospital discharge records. The comorbidities of patients with influenza were defined according to ICD-9-CM secondary diagnosis codes. Results: The highest yearly age-adjusted hospitalization rates were 30.6 and 31.1 per 100,000 populations for 2008 and 2009, respectively. In 2008, the highest hospitalization rate was among those aged 65 yrs and older; in 2009, the highest rate was among those younger than 5 yrs. Asthma was the most frequent comorbidity overall and among those younger than 50 yrs. Conversely, hypertension and heart failure were the most frequent comorbidities among those aged 50 yrs and older. Conclusion: These findings provide a better understanding of the influenza burden and may contribute to developing more effective influenza prevention strategies.