Fitter individuals are at the highest risk of death associated with delirium

Melanie Dani is a trainee in geriatric medicine in the North West Thames deanery. She is also completing a PhD at Imperial College London studying biomarkers in Alzheimer’s Disease, and has an interest in cognition and dementia.

It is well-recognised that delirium is associated with increased mortality. It’s less clear, though, whether this is the case across the spectrum of frailty. There is an idea that delirium might have bimodal outcomes – worse in frailer people, but may be protective in fitter individuals by highlighting an underlying problem early and (potentially) prompting earlier treatment.

While past studies have accounted for chronic diseases and acute illness severity, few have accounted for both. We wanted to see whether the associations of delirium with mortality remained so even after accounting for acute and chronic health factors, so we modelled both these together in a frailty index. This included 31 variables encompassing chronic disease, acute illness parameters, and functional status and was applied in a large cohort of acute medical older inpatients.

We found that delirium and frailty were both associated with increased rate of death. Indeed, the association between delirium and mortality was evident at all levels of frailty. This can be seen in Figure 2 below where the relationship with death is linear. Surprisingly, though, a higher risk of death associated with delirium was seen in the fitter end – where the two lines cross on the left part of the figure.

We predicted that delirium could be protective in fitter individuals, but we actually found the opposite – that the impact of delirium was particularly bad in fitter individuals. One reason for this could be that for fitter individuals to develop delirium, a larger insult is required. Alternatively, a distinct neurological insult in fitter individuals may cause a delirium and drive a worse progression at the same time. This study also raises some questions about the relevance of acute illness severity when determining frailty status, and how frailty should be operationalised in this context. Either way, we are again reminded that regardless of underlying reserve, delirium is a sign of global systemic decompensation, and should be treated as a medical emergency.

Read the full article Delirium, frailty and mortality: interactions in a prospective study of hospitalized older people

1 thought on “Fitter individuals are at the highest risk of death associated with delirium

  1. That is why daily delirium monitoring in hospitals is so important. Delirium is the next vital sign. At the university medical center Utrecht the Netherlands years of research resulted in a technology to objectively detect delirium, based on EEG. In 2018 nurses can use the device to scan for delirium, nearly as simple as taking a blood pressure.

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