LABORATORIO DE URGENCIAS

Differences in Intensive Care Outcomes Between Older Adults With and Without Dementia

 
A systematic review and meta-analysis

Camila S. Badell a,b,* , Maria Lizarazo Jimenez a,c , Angelica I. Lopez Jesus d  Figueroa e , Gwen Wilson g , Luis E. Palomino h , Katherine K. Fung a , Eric Tien Yen Chyn a , Eloy F. Ruiz a , Oscar J. Ponce-Ponte a,c,f
                a Geriatric Evidence & Research Initiative, Section of Geriatric Medicine, Department of Medicine, Rutgers New Jersey Medical School, Newark, NJ, USA
                b Facultad de Medicina, Universidad Peruana de Ciencias Aplicadas, Lima, Peru
                c Knowledge and Evaluation Research Unit, Mayo Clinic, Rochester, MN, USA
                d Facultad de Medicina, Universidad de San Martin de Porres, Lima, Peru
                e CaTaLiNA Cancer de Tiroides en Latinoamerica, Quito, Ecuador
                f Derriford Hospital, University Hospitals Plymouth NHS Trust, Plymouth, UK
                g Mayo Clinic Libraries, Mayo Clinic, Rochester, MN, USA
                h Hospital II Clinica Geriatrica San Isidro Labrador, Lima, Perú

                                                                                                        Journal of Critical Care (2026); 94:155553    

1.INTRODUCTION

Delivering high-quality and patient-centered care to older adults with dementia is inherently a complex challenge, as these individuals often live with multiple chronic conditions and require coordinated health and social services tailored to their unique needs [1]. Globally, an estimated 57.4 million people are living with dementia, a number pro jected to increase to 152.8 million by 2050 [2], with the burden falling disproportionately on older populations [3]. Despite its increasing prevalence, there remains limited understanding of healthcare utiliza tion patterns, contributing factors, and the appropriateness of service use among individuals with dementia. This gap highlights the need for a more comprehensive understanding of how these individuals use health care services such as emergency department visits, hospitalization ser vices, and intensive care unit (ICU) admissions [4]. Older adults with dementia now account for more than 15% of ICU admissions, and their use of intensive care has more than doubled in the past two decades [5].
Despite receiving high-intensity care, outcomes are often poor: approximately half of these patients die within one year of ICU admission [6], and many survivors experience substantial loss of functional independence and accelerated cognitive decline [7].
In addition, these patients have increased vulnerability to hospital acquired infections, delirium, and other complications [7]. These risks underline the importance of timely, patient-centered goals-of-care dis cussions with patients and their families, supported by careful prog nostic assessment to identify those most likely to derive meaningful benefit from intensive interventions [8]. Despite these concerns, the clinical trajectory and outcomes of pa tients with dementia admitted to the ICU remain incompletely under stood, limiting the ability to weigh potential benefits of critical care in this population [4,8].
A systematic review by Timmons et al. [9] re ported that hospitalized patients with dementia had longer hospital stays, and higher in-hospital mortality compared with cognitively intact peers. However, that analysis did not specifically evaluate ICU pop ulations or ICU-specific outcomes, leaving a critical knowledge gap regarding the impact of intensive care on this vulnerable group. To address this, we conducted a systematic review and meta-analysis on ICU utilization patterns, clinical trajectories, and outcomes among pa tients with dementia compared to those without dementia. Our goal is to provide a more comprehensive understanding of how intensive care affects survival, functional status, and patient-centered outcomes in this population.

2. METHODS

The protocol for this systematic review was registered with PROS PERO (CRD42024553418) and the reporting of this study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guideline [10].
2.1. Eligibility criteria
We included observational and experimental studies that assessed clinical outcomes after ICU admission among older adults with dementia compared to those without dementia.
Eligible studies enrolled participants aged 60 years or older with a confirmed diagnosis of dementia or studies enrolling adult population that reported a subgroup analysis for individuals aged 60 and above. Dementia diagnoses had to be ascer tained using recognized standardized criteria such as the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS ADRDA) guidelines, the Diagnostic and Statistical Manual of Mental Disorders (DSM), the International Classification of Diseases, 9th and 10th Edition (ICD-9, ICD-10), among others. Intensive care admission was defined broadly to include comparable settings such as medical, surgical or coronary care units. Studies were included irrespective of their follow-up duration, language of publica tion, or publication type.
Outcomes of interest included survival or mortality following ICU admission, resuscitation and code status de cisions, in-hospital complications, ICU and hospital length of stay, duration of mechanical ventilation, readmission, and discharge disposition. Articles were excluded if none of the outcomes of interest were reported.
2.2. Search strategy and selection criteria
We conducted a comprehensive search of multiple databases, from their inception through June 28, 2024, without language restrictions. The databases included Ovid MEDLINE® (Epub Ahead of Print, In Process & Other Non-Indexed Citations, and Daily), Ovid EMBASE, Scopus, and Web of Science. The search strategy was designed and executed by an experienced medical librarian in collaboration with the study's principal investigator. Controlled vocabulary terms were com bined with relevant keywords to identify studies evaluating ICU admission among individuals with dementia. Full search strategies are provided in Supplementary 1. Duplicate records were removed prior to abstract screening. Four reviewers (CSB, AILJ, DMS – S, EFR) independently screened titles and abstracts to identify potentially relevant studies. Any study included by at least one reviewer advanced to full-text screening. Full-text articles were then independently assessed by five reviewers (CSB, AILJ, FS, DMS-S, EFR). Studies were deemed eligible if included by at least two reviewers. Discrepancies were resolved through discussion and consensus with a sixth reviewer (OJP – P). For both abstract and full-text screening, articles published in languages other than English were translated using Google Translate.
2.3. Data extraction
Data extraction was performed independently by three reviewers (CSB, AILJ, TR). Any disagreements were resolved through discussion with a fourth reviewer (OJP – P). The following information was collected:
1) general study characteristics: first author, title, journal, year of publication, protocol (if available), study design, country(ies), inclusion and exclusion criteria, and dementia diagnosis criteria;
2) baseline patient characteristics: study groups, sample size, age, sex, ethnicity, Clinical Interview Schedule (CIS), and comorbidities such as cancer, diabetes, myocardial infarction, cerebrovascular disease, Chronic Obstructive Pulmonary Disease (COPD), heart failure, other pulmonary and circulatory diseases, acute renal failure, use of vaso pressors, renal replacement therapy (RRT);
3) primary clinical out comes: patient survival or mortality (ICU, hospital, and post-discharge) and in-hospital complications, such as intubation, reintubation, me chanical ventilation, feeding tube use, parenteral nutrition, resuscita tion, non-invasive ventilation, hemodialysis, delirium;
4) additional clinical outcomes: length of ICU stay, length of hospital stay, days on mechanical ventilation, readmission to the hospital or ICU, and discharge disposition (e.g., home, rehabilitation, nursing facility).
2.4. Risk of bias assessment
As only observational studies were included, risk of bias (RoB) assessment was performed using the Clarity tool for Cohort Studies [9] by one reviewer (MLJ).
A second reviewer (CSB) independently verified the assessments, and any disagreements were resolved by consensus. The RoB domains evaluated included: selection bias (assessment of exposed and non-exposed groups), recall bias (exposure assessment), reverse causation bias (ensuring outcomes were not present at the start of the study), confounding bias (matching and adjustment strategies), measurement bias (assessment of prognostic factors and outcomes), attrition bias (adequacy of follow-up period), and performance bias (co interventions between groups). The overall RoB for each study was determined as follows: studies were classified as having an overall high RoB if at least one domain was rated high risk; overall unclear RoB if no domains were rated high risk but at least one was rated as unclear; and low risk of bias only if all domains were rated as low risk.
2.5. Data synthesis and analysis
All analyses were conducted in R (version 4.4.2) using the RStudio integrated development environment. For dichotomous outcomes, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for each study, employing an intention-to-treat analysis approach. For continuous outcomes, such as days on mechanical ventilation, ICU days, and hospital length of stay after ICU admission, mean differences (MD) with 95% CI were computed. Effect size estimates (ORs and MDs) were calculated using the Knapp and Hartung method (and the corresponding confidence intervals) within the context of a random-effects model. Heterogeneity was assessed using the tau-squared (τ 2 ) statistic, and the proportion of total variation attributable to heterogeneity was quanti fied using the I-squared statistic (I 2 ).
To explore the potential impact of covariate adjustment on the results, outcomes were stratified into three groups: those with adjusted analyses, those without adjustment, and the combined group. Pooled effect sizes were then estimated separately for each group as part of a sensitivity analysis to examine heterogeneity within these strata.
2.6. Certainty assessment
The overall certainty of evidence for each outcome was appraised by using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach supported by the GRADEpro Guideline Development Tool [12]. The GRADE approach provides a structured method for rating the overall strength of a body of evidence. It considers multiple factors, including the risk of bias in individual studies, incon sistency in the results, indirectness, precision of the effect estimates, among others [12]. By weighing these domains, GRADE assigns a rating of high, moderate, low, or very low certainty (Supplementary 2). One reviewer (CSB) conducted the initial assessment, which was subse quently reviewed and discussed with a second researcher (MLJ).

3. RESULTS

From an initial 5499 records identified through database searches, 14 cohort studies met the eligibility criteria for this systematic review and meta-analysis [5,13–25]
The included studies were conducted between 2003 and 2023 across five countries: the United States of America (n = 10) [5,13,14,18,19–22,24,25], Canada (n = 1) [15], Korea (n = 1) [17], the Philippines (n = 1) [23] and Spain (n = 1) [16].
Collectively, these studies enrolled a total of 1,738,285 patients admitted to ICUs or hospitalized for acute conditions, of whom 173,107 (9.96%) had dementia and 1,565,178 (90.04%) did not. All studies used a cohort design with 12 being retrospective [5,13,15–18,19,20,22–25] and only 2 prospective [14,21].
Sex distri bution was reported in seven studies [5,15,16,19,21–22,25], where the proportion of women with dementia ranged from 46.8% to 80%, compared with 38.2% to 76.4% among those without dementia. The overall risk of bias was high in 10 studies [5,13,15–18,19,20,23,24] and low in 4 studies [14,21,22,25].  
These studies were rated as high risk of bias, mainly due to differences in co-interventions between the dementia and non-dementia group. The high risk of bias resulted from unmeasured factors influ encing treatment decisions, variability in care across centers, unequal follow-up, and the limited availability of long-term data.
3.1. Mortality
One adjusted analysis found no significant difference in ICU mor tality between patients with and without dementia (OR 1.05, 95%CI 1.00–1.10, n = 1) [16]. Similarly, unadjusted analysis from three studies also showed no significant difference (OR 0.93, 95%CI 0.70–1.24, n = 3) [16,19,21]. In contrast, patients with dementia had a higher odds of mortality at 7 days (OR 1.49, 95%CI 1.08–2.05; n = 1) [25], 30 days (OR 2.16, 95% CI 2.07–2.26; n = 2) [5,25], 90 days (OR 2.50, 95%CI 2.05–3.05; n = 1) [25] and 12 months (OR 2.91, 95%CI 2.81–3.01; n = 1) [5] following ICU admission in unadjusted analyses. Adjusted analyses supported these findings, showing increased odds of 30-day mortality (OR 1.54, 95%CI 1.47–1.62; n = 1) [5] and 12-month mortality (OR 1.95, 95%CI 1.88–2.02; n = 1) [5] among patients with dementia. These adjusted estimates accounted for sociodemographic variables (age, sex, race), dual Medicare/Medicaid eligibility, number of chronic comorbidities, and number of hospitalizations.
3.2. Resuscitation and code status decisions
In adjusted analyses, one study found no significant association be tween dementia and the likelihood of receiving resuscitation (OR 0.80, 95%CI 0.57–1.12; n = 1) [22]. However, unadjusted analyses from the same study indicated that patients with dementia were significantly less likely to receive resuscitation (OR 0.72, 95%CI 0.53–0.96, n = 1) [22. In another study, patients with dementia had significantly higher odds of code status changes toward less aggressive care in un adjusted analyses (OR 2.02, 95%CI 1.06–3.85; n = 1) [21] (Fig. 1).
3.3. ICU procedures
Intubation, reintubation, mechanical ventilation, parenteral nutrition, hemodialysis Unadjusted analyses of patients with dementia from two studies showed significantly lower odds of intubation in patients with dementia compared to those without (OR 0.59, 95%CI 0.47–0.74; n = 2) [21,22]. This finding was consistent in the adjusted analyses from one study (OR 0.67, 95%CI 0.55–0.82; n = 1) [22].
Unadjusted analyses from nine studies showed no significant difference in the odds for receiving me chanical ventilation (OR 0.91, 95%CI 0.61–1.37; n = 9) [13,17–18,20–25]. In contrast, adjusted analyses from four studies demonstrated significantly lower odds of mechanical ventilation (OR 0.69, 95%CI 0.60–0.80; n = 4) [13,17,22,25] in patients with dementia. Age-stratified unadjusted analyses further explored the duration of mechanical ventilation. For mechanical ventilation 84 years (OR 1.43, 95% CI 1.19–1.71; n = 1) [16].
In contrast, for mechanical ventilation ≥96 h, patients aged 65–74 years showed no significant difference (OR 1.02, 95%CI 0.93–1.13; n = 1), whereas significantly lower odds were observed in the 75–84 years group (OR 0.86, 95%CI 0.80–0.93; n = 1) and in those aged >84 years (OR 0.71, 95%CI 0.59–0.85; n = 1) [16]. Additionally, one study reported no significant difference in the odds of reintubation in people with dementia in unadjusted analysis compared to patients without dementia (OR 0.29, 95%CI 0.06–1.31; n = 1) [21]. For feeding tube use, no statistically significant differences were observed in either unadjusted analyses for patients with dementia compared to those without dementia (OR 1.11, 95%CI 0.81–1.53; n = 2) [21,22] or in the adjusted analysis (OR 1.23, 95%CI 0.80–1.90; n = 1) [22]. Similarly, unadjusted analyses showed no statistically significant differences in the odds of parenteral nutrition (OR 0.36, 95%CI 0.11–1.22; n = 1) [21], or hemodialysis in the unadjusted analysis (OR 0.76, 95% CI 0.28–2.03) [21]. (Fig. 2).
3.4. ICU complications:
Delirium For delirium, unadjusted analyses from one study showed signifi cantly higher odds in patients with dementia compared to those without dementia (OR 4.80, 95%CI 1.81–12.72; n = 1) [14].
3.5. Duration of life support and hospital stay
Unadjusted analyses of days on mechanical ventilation showed no statistically significant difference between patients with and without dementia (MD –11 days, 95%CI –33.5 to 11.5; n = 3) [15,21,25]. Similarly, unadjusted analyses found no statistically significant differ ence in ICU length of stay (MD –4.2 days, 95%CI –11.3 to 2.9; n = 3) [19,21,25]. In contrast, one unadjusted analysis reported a significantly shorter hospital length of stay after ICU admission among patients with dementia (MD–1 day, 95%CI –1.6 to 0.4; n = 1) [25].
3.6. Discharge disposition
Adjusted analyses from one study showed that patients with de mentia had significantly lower odds of being discharged home compared to those without dementia (OR 0.40, 95%CI 0.39–0.42; n = 1) [5]. In contrast, unadjusted analyses found no statistically significant differ ence in the likelihood of discharge to nursing facilities (OR 0.98, 95%CI 0.43–2.26; n = 1) [21] (Fig. 4).
3.7. Quality of evidence
The certainty of the evidence varied from very low to moderate, as all outcomes were based on observational cohort studies. Most outcomes, including ICU mortality, 7-day mortality, 90-day mortality, resuscita tion, code status, delirium, intubation, feeding tube, days on mechanical ventilation and hospital length of stay after ICU, were rated as low certainty due to risks of bias, residual confounding, and imprecision. Moderate certainty was assigned to outcomes showing consistent or large adjusted effects, such as 30-day and 12-month mortality, me chanical ventilation and discharge to home.
Very low certainty was applied to outcomes derived from small or highly imprecise studies, including parenteral nutrition, renal complications, reintubation, discharge to a nursing facility and ICU days.
The evidence indicates possible differences in care intensity and mortality among patients with dementia, but confidence in these findings remains limited by the observational nature of the data.

4. DISCUSSION

This systematic review and meta-analysis synthesized evidence from 14 cohort studies, including over 1,738,285 critically ill patients, approximately 10% of whom had dementia. Across the included studies, adjusted analyses showed no significant difference in ICU mortality between patients with and without dementia (OR 1.05, 95%CI 1.00–1.10; n = 1) [16], but significantly higher odds of 30-day mortality (OR 1.54, 95%CI 1.47–1.62; n = 1) [10] and 12-month mortality (OR 1.95, 95%CI 1.88–2.02; n = 1) [10]. Regarding resuscitation and code status decisions, one adjusted analysis found no significant association between dementia and resuscitation (OR 0.80, 95%CI 0.57–1.12; n = 1) [19], while unadjusted analysis from another study reported higher odds of code status changes toward less aggressive care (OR 2.02, 95%CI 1.06–3.85; n = 1) [28].
For hospital complications, adjusted analyses demonstrated lower odds of intubation (OR 0.67, 95%CI 0.55–0.82; n = 1) [19] and mechanical ventilation (OR 0.69, 95%CI 0.60–0.80; n = 4) [3,8,19,39] in patients with dementia, with no significant dif ferences for feeding tube use (OR 1.23, 95%CI 0.80–1.90; n = 1) [19] or parenteral nutrition (OR 0.36, 95%CI 0.11–1.22; n = 1) [28]. However, unadjusted analysis showed markedly higher odds of delirium (OR 4.80, 95%CI 1.81–12.72; n = 1) [23].
For secondary outcomes, adjusted analysis showed patients with dementia were less likely to be discharged home (OR 0.40, 95%CI 0.39–0.42; n = 1) [10], while unadjusted ana lyses reported no significant differences in ICU length of stay (MD –4.2 days, 95%CI –11.3 to 2.9; n = 3) [18,28,39]. Although both adjusted and unadjusted analyses showed no significant difference in ICU mortality between patients with and without
demonstrated higher mortality among those with dementia. These results align with the increased risk of post-ICU mortality observed among patients with dementia, suggesting that dementia is contributing inde pendently to worse outcomes, likely due to poorer nutritional status, worsening physical function, frailty, reduced mobility [27], and increased risk of delirium [26] all of which diminish physiological reserve.
Frailty is highly prevalent among individuals with dementia and is independently associated with poorer outcomes, including mor tality [28]. Residual confounding by frailty may therefore partially explain the observed excess mortality in this group. Unfortunately, none of the included studies directly measured or was adjusted for it. Frailty, for instance, may also increase vulnerability to acute stressors during critical illness, particularly the development of delirium. Because delirium is frequently underdiagnosed [29,30], it is likely an important mediator of both short- and long-term increased mortality [31], as well as other adverse outcomes such as prolonged ICU stays, higher utiliza tion of physical restraints or antipsychotics, and accelerated functional decline [32–34].
In addition, ICU admission among patients with dementia may reflect a selection process favoring individuals with milder cognitive impairment or lower levels of frailty. Intensivists may be less likely to admit patients with advanced dementia, particularly those residing in long-term care facilities, due to limited anticipated benefit from inten sive care. Such selection bias could help explain the absence of differ ences in ICU mortality between patients with and without dementia, despite remaining persistently higher following ICU discharge.
The intersection between dementia, frailty and ICU delirium therefore rep resents a compounded risk for poor outcomes, highlighting the need for targeted prevention and management strategies in critically ill older adults [35]. Future research should also consider stratifying outcomes by dementia severity and baseline frailty to better understand how pa tient selection affects ICU outcomes.
Our findings also indicate that patients with dementia were less likely to undergo intubation or mechanical ventilation. This pattern may reflect patient and family preferences, clinician judgment and shared decision-making, or greater prognostic awareness. As such, code status changes could act as a potential confounding factor in ICU outcomes analysis, especially in studies assessing length of stay, mortality, and interventions during admission, since these decisions may reflect care preferences rather than illness severity alone. Indeed, one study from our systematic review found significantly higher risk of code status changes toward less aggressive care which is consistent with previous reports that goals-of-care discussions in this population often lead to less aggressive approaches [5]. It is also important to consider the role of acute clinical complications, such as sepsis, acute respiratory distress syndrome, or traumatic brain injury, which may independently influ ence ICU interventions and outcomes.
The absence of an observed as sociation between dementia and mechanical ventilation or hospital length of stay may therefore reflect differences in the prevalence or severity of these complications rather than the effect of dementia itself.
Future studies should adjust for both the presence and severity of acute clinical complications, as well as code status and goals-of-care decisions, to better clarify the independent contribution of dementia to ICU in terventions and outcomes.
While ICU length of stay and ventilation duration did not differ by dementia status, patients with dementia had shorter hospital stays and were less likely to be discharged home.
These findings are consistent with previous studies showing higher rates of institutional discharge and in-hospital mortality among cognitively impaired populations [36], which may help explain the shorter hospitalizations observed. It is important to recognize that our observed outcomes such as ICU length of stay, complication rates, and mortality may also be influenced by characteristics of the healthcare system.
Our results come from six different countries, and institutional policies (e.g. ICU admission thresholds, access to geriatric or palliative care consultation, and implementation of delirium-prevention protocols) likely shaped both care processes and outcomes [37]. Regional practices related to advance care planning, including the use of do-not-resuscitate (DNR) orders, may influence treatment intensity and survival [38].
Moreover, systems with greater investment in dementia and geriatric services may be more inclined to admit patients with cognitive impairment to the ICU, potentially influencing both patient selection and reported outcomes [39]. Therefore, while our findings align with existing literature, they should be interpreted in the context of local healthcare structures, which may limit generalizability to settings with different resource levels, populations, or models of care.
This review has several strengths, including a comprehensive search strategy, a large, aggregated sample size, and inclusion of both retro spective and prospective studies. The use of both unadjusted and adjusted effect estimates also enables a more nuanced interpretation of the association between dementia and ICU outcomes while accounting for confounding variables.
Nonetheless, important limitations must also be acknowledged.
* First, 12 [5,13,15–18,19,20,22–25] of the included studies were retrospective and relied on administrative coding to ascertain dementia diagnoses, which may have led to misclassification. Although some studies supplemented coding with pharmacy records [17] or validated clinical assessments [14,21], heterogeneity in case definitions, population characteristics and study design remained po tential sources of bias, as reflected by higher tau-squared and I-squared values for some outcomes.
* Second, none of the studies stratified out comes by dementia severity, an important determinant of prognosis in critically ill patients [11], and few adjusted for residual confounders such as preexisting advanced care plans or frailty.
* Third, several out comes, including resuscitation [19], code status change [28], and delirium [23], were reported by only one study limiting the generalizability of these findings.
* Fourth, most studies were conducted in high income countries [5,13–22,24,25], which may limit applicability to lower-resource settings.
* Finally, another important limitation of the available evidence is the absence of data on genetic and preclinical factors, such as apolipoprotein E (ApoE) genotype and markers of am yloid and tau burden. In addition, none of the included studies reported frailty status. These underlying biological factors may influence both the trajectory of cognitive decline and clinical outcomes during critical illness. Therefore, residual confounding due to unmeasured variables remains likely, which limits the casual interpretation of our findings.
Future research that integrates genetic, biomarker, and clinical data will be essential to better elucidate how underlying disease biology modifies ICU outcomes.
This systematic review and meta-analysis demonstrate that older adults with dementia admitted to the ICU have distinct clinical trajectories and outcomes. Dementia was associated with higher short and long-term mortality and greater risk of delirium, and while it does not increase healthcare utilization, affected patients are more likely to require institutional care after hospitalization.
Future research should focus on prospective, multicenter studies employing standardized definitions of dementia and incorporating measures of dementia severity, frailty, comorbidity burden, and baseline functional status to better guide care and decision-making.

NOTE: This is a full text. Tables, graphs, figures, and further details can be found in the journal mentioned at the beginning.

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