Hospitalization of individuals is often necessary, but it can be associated with several risks. For example, among older adults, hospitalization has been linked to an increased risk of loss of independence. It is difficult to determine, however, whether such adverse outcomes are due to hospitalization or the condition that brought the individual to the hospital. A recently published study from the Chicago Health and Aging Project examines the hypothesis that hospitalization puts older adults at increased risk for cognitive decline.
The study included older adults from a geographically specified area of Chicago. Participants were administered cognitive assessments every three years beginning in 1993. As part of the study, the researchers accessed the participants’ Medicare records, which enabled them to identify which participants had been hospitalized, as well as the type and severity of illness that led to hospitalization. Participants were also assessed for depressive symptoms and disability. The researchers hypothesized that, when controlling for demographic, educational, and health factors, participants would show a higher rate of cognitive decline following hospitalization.
For this study, the researchers included all project participants who had been hospitalized and who had been administered at least three cognitive assessments, including at least one assessment before hospitalization. Based on those criteria, the participants tested their hypothesis about hospitalization and cognitive decline using data on 1,335 participants, who had completed between three and five cognitive assessments. The researchers analyzed the rate of cognitive decline both before and after hospitalization, examining the influence of other factors such as baseline cognitive ability, education, and age.
The authors found that, when controlling for severity of illness and other relevant factors, individuals experienced cognitive decline at 2.4 times the rate they had before hospitalization. Those with more serious illness and who had longer hospital stays had faster rates of post-hospital cognitive decline, suggesting that the underlying medical condition may have contributed to the accelerated decline. However, the statistical effect of illness severity was not sufficient to explain much of the acceleration in decline.
The authors suggested that delirium, which affects an estimated 15 to 20 percent of hospitalized older adults, may be a contributing factor, but that their study was not able to include sufficient data about the participants’ experiences of hospitalization to explore this hypothesis. Further research may be able to provide more information about hospitalization as a risk factor, and may lead to ways to reduce some of this risk.