Influenza hospitalizations among american indian/alaska native people and in the United States general population

Prabhu P Gounder; Laura S Callinan; Robert C Holman; Po-Yung Cheng; Michael G Bruce; John T Redd; Claudia A Steiner; Joseph Bresee; Thomas W Hennessy

doi:10.1093/ofid/ofu031

Influenza hospitalizations among american indian/alaska native people and in the United States general population

Open Forum Infect Dis. 2014 Jun 10;1(1):ofu031. doi: 10.1093/ofid/ofu031. eCollection 2014 Mar.

Authors

Prabhu P Gounder¹, Laura S Callinan², Robert C Holman², Po-Yung Cheng³, Michael G Bruce¹, John T Redd⁴, Claudia A Steiner⁵, Joseph Bresee³, Thomas W Hennessy¹

Affiliations

¹ Arctic Investigations Program, Division of Preparedness and Emerging Infections, National Center for Zoonotic and Emerging Infectious Diseases , Centers for Disease Control and Prevention , Anchorage, Alaska.
² Division of High-Consequence Pathogens and Pathology, National Center for Zoonotic and Emerging Infectious Diseases.
³ Influenza Division, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
⁴ Indian Health Service , Santa Fe, New Mexico.
⁵ Healthcare Cost and Utilization Project, Center for Delivery, Organizations, and Markets, Agency for Healthcare Research and Quality , US Department of Health and Human Services , Rockville, Maryland.

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.

Keywords: American Indian; epidemiology; healthcare disparities; influenza.