Delirium, dementia and in-hospital mortality: the results from the Italian Delirium Day 2016, a national multicenter study

Background: There is little evidence about the prevalence of cognitive disorders and their effect on in-hospital mortality in large multicenter studies. The objectives of the 2016th edition of the "Italian Delirium Day", a large multicenter study on in-hospital older patients, were to assess: 1) the point-prevalence of cognitive impairment/no dementia, dementia, delirium and delirium superimposed on dementia, DSD; and 2) the effect of these conditions on in-hospital mortality.

Methods: This multicenter study and included 2037 older patients (aged ≥65 years) admitted to acute medical and surgical wards across 205 acute hospitals. The four cognitive disorders groups were defined with a structured approach including the 4 AT and the presence of a documented diagnosis of dementia. The outcome measure was in hospital mortality, as reported by the researchers involved in the study in each center.

Results: The mean age was 81.17±7.7 years. Overall, 893 patients (43.8%) had neither delirium, nor dementia nor cognitive impairment, 483 (23.7%) had cognitive impairment/no dementia, 230 (11.3%) dementia alone, 187 (9.2%) delirium alone and 244 (12.0%) DSD. Overall, 99 (4.8%) patients died. Participants with delirium alone (Odds Ratio, O.R. 2.56, 95% Confidence interval, C.I. 1.29-5.09) and those with DSD (OR. 2.60, 95% C.I. 1.39-4.85) had higher mortality risk compared to the reference group of patients with "no cognitive impairment".

Conclusions: Delirium and DSD were highly prevalent among older hospitalized patients and significantly increased in-hospital mortality. Clinicians should systematically assess these conditions and recognize them as markers of critical conditions and predictors of imminent death.