The most common reasons for hospitalization – regardless of dementia status – were circulatory, respiratory, and digestive disorders. Among participants with dementia, the average annual admission rate was 419 admissions per 1,000 persons – more than twice that of those without dementia, who averaged 200 admissions per 1,000 persons each year. After age/sex adjustment, the ratio of admission rates was 1.57 and was 1.41 after adjustment for additional covariates.
In the fully adjusted model, admission rates for five types of disorders (circulatory, genitourinary, infectious, neurologic, and respiratory) were significantly greater among participants with dementia, compared with those without dementia. In contrast, those with dementia had significantly lower admission rates for musculoskeletal disorders.
ACSCs were analyzed separately. The admission rate ratio was 1.78, after full adjustment for covariates. Importantly, three ACSCs – bacterial pneumonia, heart failure, and urinary tract infection – accounted for two-thirds of all potentially preventable admissions; admission rates among those with dementia were significantly greater for all three conditions. Admission rates for dehydration and duodenal ulcer, though low overall, also were significantly greater among those with dementia. Admissions for ACSCs accounted for 28% of all hospitalizations among those with dementia vs. only 19% of all admissions among those who remained dementia free.
The authors speculated about why dementia might lead to more frequent hospitalization. First, underlying conditions that increase the risk of dementia such as stroke, or that develop in the setting of dementia, such as trouble swallowing, which raises the risk of pneumonia, might increase the risk of hospitalization.
"Second, because of its primary deleterious effects on global cognition, executive function, expressive language, symptom perception, and awareness of deficits, dementia impairs the ability to self-manage chronic conditions and to pinpoint symptoms and alert others to their presence, thereby creating substantial diagnostic and treatment challenges for primary care clinicians," the researchers wrote.
Situational factors also might contribute, including a change of living situation, or the temporary or permanent absence of a caregiver who is familiar with the person’s usual habits, behaviors, and ongoing general medical management.
They also cited another potential explanation – the threshold for hospitalizing such persons might be lower because dementia "increases central nervous system vulnerability to the metabolic effects of acute illness, such that for a comparable severity of illness, persons with dementia are in fact sicker."
The authors reported that they have no conflicts of interest. The ACT study is supported by a grant from the National Institute on Aging.