Influenza Hospitalizations Among American Indian/Alaska Native People and in the United States General Population

Abstract

Abstract Background.  Historically, American Indian/Alaska Native (AI/AN) people have experienced a disproportionate burden of infectious disease morbidity compared with the general US population. We evaluated whether a disparity in influenza hospitalizations exists between AI/AN people and the general US population. Methods.  We used Indian Health Service hospital discharge data (2001–2011) for AI/AN people and 13 State Inpatient Databases (2001–2008) to provide a comparison to the US population. Hospitalization rates were calculated by respiratory year (July–June). Influenza-specific hospitalizations were defined as discharges with any influenza diagnoses. Influenza-associated hospitalizations were calculated using negative binomial regression models that incorporated hospitalization and influenza laboratory surveillance data. Results.  The mean influenza-specific hospitalization rate/100 000 persons/year during the 2001–2002 to 2007–2008 respiratory years was 18.6 for AI/AN people and 15.6 for the comparison US population. The age-adjusted influenza-associated hospitalization rate for AI/AN people (98.2; 95% confidence interval [CI], 51.6–317.8) was similar to the comparison US population (58.2; CI, 34.7–172.2). By age, influenza-associated hospitalization rates were significantly higher among AI/AN infants (<1 year) (1070.7; CI, 640.7–2969.5) than the comparison US infant population (210.2; CI, 153.5–478.5). Conclusions.  American Indian/Alaska Native people had higher influenza-specific hospitalization rates than the comparison US population; a significant influenza-associated hospitalization rate disparity was detected only among AI/AN infants because of the wide CIs inherent to the model. Taken together, the influenza-specific and influenza-associated hospitalization rates suggest that AI/AN people might suffer disproportionately from influenza illness compared with the general US population.