Outcomes and cost analysis of patients with dementia in the intensive care unit: a population-based cohort study

In this retrospective population-based cohort study, we describe the characteristics, outcomes, and cost patterns of patients with dementia admitted to the ICU and non-ICU hospital settings. Patients with dementia admitted to the ICU are younger, more comorbid, and less likely to be transferred from home or assisted living institutions. They have a longer total LOS, increased interventions, and higher mortality. They have less severe baseline impairment or functional impairment post-discharge. They were more frequently readmitted to ICU. Patients with dementia admitted to the ICU, despite representing less than 10% of the cohort, incurred higher total healthcare costs, totalling $762 million for our cohort.

We characterize patients with dementia who are admitted to the ICU as younger, more comorbid, more functionally impaired but with less severe cognitive impairment, as compared to those admitted to non-ICU hospital settings. However, they had higher in-hospital mortality, and nearly 50% mortality one year after discharge. Taken together, these findings may suggest that patients with dementia admitted to the ICU are frailer than those outside of the ICU, but had a higher severity of illness resulting in increased mortality. This is in keeping with the reported literature [27, 28]. We note that there was no significant difference in income status and rurality between the cohorts, suggesting these social determinants of health do not seem to impact who is admitted to the ICU setting. The higher mortality and increased functional impairment and frailty in patients with dementia in the ICU may suggest against offering aggressive medical management. However, we note these patients have lower rates of cognitive impairment, suggesting they may have been risk-stratified prior to admission as to who would benefit from ICU care. We note that more severe cognitive impairment in the ICU cohort is associated with increased mortality, and should be considered in the process of evaluating who may benefit from more aggressive medical management. The decision of offering ICU care also needs to be considered in the context of other variables that are associated with increased mortality, which in our study included older age, male sex, and multi-morbidity, consistent with previous studies and closely interlinked with frailty [29, 30]. In our study, there was a very low rate of palliative care involvement in both cohorts (< 2%); however, this primarily reflects palliative care admissions rather than consultations, the latter of which is often a source of advanced care planning. Additionally, perhaps goals of care discussions took place prior to hospitalization, or outside of formal palliative care involvement, given the well-known repercussions of increased mortality, frailty, and worsened quality of life in patients with dementia [31]. However, we found that patients were more likely to be admitted to the ICU if they had a prior hospital admission, and nearly twice as likely to be re-admitted to the ICU. Goals of care discussions have the potential to optimize quality of care while reducing futile care, and are particularly important in this vulnerable population [32]. Further research to stratify which patients with dementia have increased survival benefit and may benefit from ICU admission is necessary, as well as the impact of advanced care planning on ICU admissions in this population.

We demonstrate that patients with dementia who are critically ill admitted to the ICU incur increased costs in comparison to those admitted to non-ICU hospital settings. For our cohort, this is likely in part driven by increased total LOS and increased interventions seen in the patients admitted to ICU. Previous studies have described the impact of LOS and interventions such as invasive mechanical ventilation in prolonging LOS for patients in critical care [33‐36]. Dispositioning costs were the second highest driver of costs overall. Costs were increased for critically ill patients needing rehabilitation and complex continuing care, but conversely higher for long-term care in the non-ICU group. Patients with dementia become frailer after hospitalization, therefore requiring costly dispositioning for increased supports in their post-discharge recovery [37]. As patients had more severe cognitive impairment in the non-ICU group, this may explain the need for institutionalization. This highlights the importance of increasing the number of community supports to improve flow in the hospital and reduce unnecessary acute care stay [38]. Furthermore, it represents the need for early goals of care discussion and palliative care involvement. Palliative care has been linked to reducing ICU LOS and costs, and early goals of care discussions have been associated with reduced mortality, ICU use, and hospitalization [39‐41]. Future studies should explore strategies to mitigate costs while optimizing quality, patient-centered care for this vulnerable population.

This study has several limitations. Firstly, we utilized health administrative data which lacks certain clinical variables such as severity of illness or admission diagnoses, as well as social determinants of health such as ethnicity data. While we include comparative analysis, there are limitations in making certain conclusions given these lack of clinical variables, such as whether patients admitted to the ICU have higher acuity accounting for the decision to offer ICU care. The use of coding data for various diagnoses such as delirium likely underestimates the true incidence in our population, limiting interpretation of its impact in both ICU and non-ICU settings. We note a small proportion of patients in the non-ICU setting received invasive ventilation; this is likely because therapy was initiated in this setting and was coded as such, before the patient was ultimately transferred to the ICU for ongoing care, which affects analysis of these results. Furthermore, there is a lack of certain variables such as vasoactive medications to explain reasons for ICU admission. Location prior to hospitalization, dementia severity, and functional data was available for a subset of patients only, which limits our interpretation and generalizability of how these variables impact ICU admission. Furthermore, while palliative care involvement during hospitalization was available, information about goals of care discussions and palliative care involvement prior to hospital admission was unavailable, which would be tremendously valuable and better inform if early discussions influence ICU or non-ICU hospital admission in this vulnerable patient population. Cost data was available for several categories; however, separate ICU and non-ICU hospital costs, as well as other cost breakdowns such as procedural interventions and outpatient palliative care, were not obtainable, which could help identify major drivers of increased cost. Furthermore, while our cost data allows for some comparison between the cohorts, there are differences in baseline patient characteristics, and so implications per patient encounter must be interpreted with caution. Finally, the retrospective nature of this study allows association, but not causation, to be determined.