Infection may increase mortality risk in dementia

Post-infection mortality is higher in older patients with dementia than those without in an analysis of Danish national registry data presented at AAIC 2020.

Among 1.5 million older patients followed for a total of nearly 13 million years, those with dementia and infection-related hospital visits had greater than sixfold increased risk of dying vs those without dementia or an infection.

“Increased mortality is observed across all infection types in patients with dementia … increased mortality is seen both short and long term in the study,” said co-investigator Janet Janbek, a PhD student at the Danish Dementia Research Center, Rigshospitalet, University of Copenhagen, Denmark.

Janbek and team looked at data from Danish national health registries among individuals aged 65 years and older who had visited the hospital for an infection. There were 575,260 deaths during more than 12.7 million person-years of follow-up, including 82, 573 individuals with dementia. [AAIC 2020, poster 38941]

Patients with dementia and infections had a mortality rate ratio (MRR) of 6.52 compared to those without dementia or an infection. Those with either dementia or infection alone had a threefold increased rate of death (MRR, 3.12 and 3.19, respectively).

Mortality rate highest within 30 days of hospital visit

MRRs were highest within 30 days following a hospital visit for infection in the dementia group. The rate remained elevated for 10 years after the initial hospital visit.

Mortality rates from all infections were elevated in those with vs those without dementia. The rates were highest with sepsis and lowest with ear infections.

Janbek said the association between infection and increased mortality risk in those with dementia might be because patients with dementia have become reliant on external care and turned out physically weak with declined functional levels following hospital visit due to severe infection.  

Another plausible explanation might be because patients with dementia have more severe infections which could explicate the higher mortality rates, she added.

“It is also plausible that infections play a role in worsening dementia and subsequently lead to increased mortality in these patients,” Janbek explained.

The road ahead

The study highlights the need for better clinical management and post-hospital care for older adults with dementia following infections, she added. “We need to identify possible preventive measures and targeted interventions in people with dementia and infections to increase their quality of life.”

“The findings also encourage [more] research to further our understanding into which cascade of events or risk factors can explain the increased mortality we observed following infections in patients with dementia,” Janbek concluded.