Very elderly (aged 80 or older) patients are being admitted to intensive care units (ICUs) in increasing numbers [1–3]. More concerning is that these admissions may occur despite the preference of many elderly patients to avoid unnecessary prolongation of life by life-sustaining therapy [4–6]. In spite of this, more than 70% of seriously ill hospitalized elderly patients do not discuss these preferences with their healthcare providers [6], which may result in provision of life-sustaining therapy even when patients prefer care focused on improved comfort and quality of life [7–10].

In our prospective, observational cohort of very elderly patients admitted to ICUs in Canada, not only was hospital and 12-month mortality high [11], but surviving individuals had a low probability of returning to baseline physical function [12]. Other studies have corroborated the findings of poor short- and long-term outcomes in this patient population [13–16]. These observations raised important questions about the appropriateness of both admission to and long-term treatment in the ICU for this population.

There is presently unprecedented strain on the healthcare system in the face of the baby boomer effect and increases in life expectancy [17], and critical care remains amongst the most expensive of healthcare interventions, consuming approximately 1% of the GDP [18, 19]. These costs continue to rise, and are expected to increase further as the incidence of critical illness requiring ICU admission is projected to increase by 80% by 2026 [19, 20]. There are significant economic implications surrounding admission of very elderly patients to the ICU, as the costs of providing prolonged and potentially non-beneficial care in this population are likely considerable. While ICU costs in elderly patients have been reported in smaller retrospective and prospective cohorts, estimates have ranged widely depending on the type of cost presented and the method of cost estimation [21–25].

The primary objective of this study was to determine contemporary costs of care for very elderly patients admitted to ICUs using our large prospective Canadian cohort. In addition, we sought to determine potentially predictive patient and family factors influencing cost of care.

In this multicentre cohort study, we demonstrated the significant cost of ICU admission in very elderly patients—approximately $32,000 per patient. Despite this cost, clinical outcomes were poor: 35% of patients died in hospital and 41% of those followed longitudinally were deceased at 1 year. This amounts to an ICU cost alone of nearly $49,000 per survivor to discharge for the unselected cohort, and $62,000 per survivor at 1 year amongst those in the longitudinal study. In addition, we demonstrated important patient and family factors that influence the cost of care; specifically, a preference for comfort measures over life support was an independent predictor for lower cost of care, and remained a predictor for both survivors and decedents.

Our reported cost of ICU admission in very elderly Canadians of $31,679 per patient is considerably higher than most studies reporting the cost of ICU care in similar populations [21–25]. Interpretation of cost differences between studies, however, remains inaccurate and may be misleading given the various types of costs reported and differences in methods of cost calculation. As a result, previous studies that calculated the cost of ICU admission in elderly and very elderly patients report a wide range of costs, from approximately $3300 to $28,100 USD per patient [21–25]. The daily ICU cost per patient in the present study, however, was similar compared with reported figures from cohorts that also included non-elderly adult patients [18, 25, 31]. For Canadian adults, a recent report estimated an average daily ICU cost of $3592 with an average length of stay in the ICU of 3 days [32]. Altogether, the similar daily cost but longer total length of stay in the ICU for the very elderly patients in our cohort compared to the general adult ICU population likely accounts for the notably higher overall cost of ICU admission [31, 32]. Although some studies suggest that very elderly patients admitted to ICU may incur fewer costs compared to their younger counterparts as a result of less aggressive care, our study did not directly compare costs to younger patient cohorts or study the costs associated with specific interventions [21, 22]. This trend towards fewer invasive interventions in very elderly patients, however, was not observed in our cohort, 85% of whom received at least one form of life-sustaining therapy and 72% of whom were mechanically ventilated [11], contrasting with the estimated rate of mechanical ventilation in the general adult ICU population in Canada of 33% [32]. This might, in fact, suggest that average daily ICU costs may underestimate costs for elderly patients and overestimate costs for younger adults.

The cost of ICU stay for the very elderly becomes more striking when contemplated in light of clinical outcomes observed in this population. Without even considering the costs of non-ICU hospitalization or readmission, long-term care, and outpatient care, the cost of ICU alone in our study was over $60,000 per survivor at 1 year. Though 1-year mortality was greater than 40% in our study, other investigators have reported that long-term mortality may be even higher in this group (55–90% at 3 years) [15, 16, 33]. Furthermore, we recently showed, in the same cohort as the present study, that at 1 year only 26% of patients had survived and recovered back to, or near, their baseline level of functioning [12]. As such, the ICU and non-ICU costs per functional survivor are likely substantially higher than the exclusive ICU costs we present. Potential explanations for the differences in mortality and length of stay between the hospital and longitudinal cohorts are discussed in greater detail in earlier reports [11, 12].

Even more important than the clinical outcomes were the apparent incongruences between patient/family wishes and the provision of life-sustaining treatment received, which many elderly patients would have preferred to avoid [4–6]. Nearly one quarter of patients or their caregivers in the present study had an expressed preference for comfort measures over life support, yet were admitted to ICU and received life-sustaining therapy. These observations should prompt healthcare providers to re-evaluate the benefit of ICU care for the very elderly, and suggest that patients’ preferences and goals of care are not addressed early enough to prevent unwanted healthcare interventions or ICU admissions.

Mechanical ventilation has been shown to increase ICU costs [31]. This may partially explain why respiratory diagnoses in our cohort were associated with the highest costs in our study. The observation that cardiovascular diagnoses were the least costly probably reflects the inclusion of post-operative cardiac and vascular surgery patients in this group—patients who may have more predictable ICU courses, preselected based on fitness for surgery. Perhaps not surprisingly, older age and greater SOFA scores in non-survivors were associated with a lower cost, likely because they were predictors of earlier mortality. In survivors to discharge, why older age was a predictor of lower cost and why we observed conflicting results with respect to comorbidity index and illness severity scores as cost-predictive factors remains unclear.

Interestingly, we found that patients whose family members had specified a preference for comfort care over life support had a significantly lower cost of ICU care, not only for those who died in hospital, but also for survivors to discharge. This finding suggests that, without adversely affecting clinical outcomes, an approach that focuses early on comfort measures instead of life support led to a reduction in cost. This is corroborated by our recent work which demonstrated that palliative care consultation reduced ICU length of stay [34].

The main limitations to our study surrounded the calculation of ICU cost. Our cost estimates were based on figures from a single academic institution, and therefore do not account for variability in costs between institutions and the known lower costs in the community ICU setting [32]. Additionally, costs were estimated by ICU dates of admission (length of stay), and therefore specific costs of care for each patient were not captured. These are known limitations to this validated method of cost calculation [35]. Finally, inpatient and outpatient costs of care following ICU discharge were not ascertained, and would be an important consideration as many of these patients have extended hospitalizations and a prolonged recovery period.

Our large multicentre cohort provides a unique and representative population to define the cost of critical care for the very elderly, which is higher than in the general adult ICU population despite more than double the ICU mortality rate [32]. Considering that very elderly patients frequently express a desire for a good quality of life over life-sustaining therapy, our finding that a family preference for comfort care was a predictor for lower ICU cost provides further impetus for early goals of care discussion and the development of tools for recognition of patients with probable poor outcomes [36]. Our reported cost figures will be important to inform future clinical, policymaking, and funding decisions aiming to reduce financial strain on our medical system and ensure appropriate allocation of healthcare resources. Ultimately, this will require systemic changes in end-of-life care, specifically surrounding the decisions to continue life-sustaining therapy for an elderly patient with multiple comorbidities in the ICU.