Infectious disease hospitalizations among older adults in the United States from 1990 through 2002

Background: To understand conditions associated with substantial morbidity among older adults (aged 65 years), we describe hospitalization rates and trends for overall infectious disease (ID) and for specific ID groups among older adults in the United States from January 1, 1990, through December 31, 2002. Methods: The National Hospital Discharge Survey was used to generate hospitalization estimates from 1990 through 2002 for the US population of older adults. By using a comprehensive list of International Classification of Diseases, Ninth Revision, Clinical Modification codes associated with IDs, we identified and analyzed hospitalizations associated with specific ID and ID-related categories. Results: There were approximately 21.4 million (SE, 636 000) ID hospitalizations among older adults from 1990 through 2002, and between 1990 through 1992 and 2000 through 2002, the ID hospitalization rate increased 13% from 449.4 to 507.9 hospitalizations per 10 000 older adults (P = .01). This increase was caused in part by the increasing relative contributions of patients aged 75 through 84 years and 85 years or older to the older adult ID hospitalization rate. Almost half of ID hospitalizations (46% [SE, 0.7%]) and ID-related hospital deaths (48% [SE, 1.6%]) among older adults were associated with lower respiratory tract infections from 2000 through 2002. Conclusions: The hospitalization rate for IDs increased slightly among the older adult US population during the 13-year study and was associated with the aging of the older adult population. The reduction of ID hospitalization rates among older adults could help attenuate the anticipated increase in the number of hospitalizations among older adults and should be a high priority given the projected population growth among older adults in the United States.