Principal findings
In this comprehensive cost-analysis study, we found that the burden of ICU-treated TBI, ICH, SAH and AIS has markedly increased during the past decade in Finland. This is mainly due to an increased number of patients requiring neurocritical care being admitted to the ICU, as mean cost per patient slightly decreased during the study period. The decrease in mean cost per patient probably reflects the fact that severity of illness was less in all diagnostic groups, indicating that more patients with less severe neurocritical illness are treated in the ICU nowadays. We also identified major differences in treatment costs and cost-effectiveness in patients with TBI, SAH, ICH or AIS. Intensive care of patients with TBI or SAH resulted more commonly in patients becoming independent survivors and was associated with lower treatment costs compared to ICH and AIS. That said, it should be noted that a direct comparison between patients with TBI, ICH, SAH or AIS is challenging due to the varied spectrum of patient demographics, natural history, ICU admission thresholds, treatment options and strategies and baseline prognosis.
Comparison with other studies
There are no studies that have comprehensively included several neurocritical illnesses. Regarding ICH and SAH, a recent study from Ontario, showed that total direct and indirect hospital costs for patients with spontaneous ICH was $53,491 (expressed in Canadian dollars at the 2017 rate, converts to €35,303 at the 2013 rate) and $92,794 (expressed in Canadian dollars at the 2017 rate, converts to €61,243 at the 2013 rate) for patients with SAH [
22]. The mean cost per SAH hospital survivor was $136,097 (expressed in Canadian dollars at the 2017 rate, converts to €89,797 at the 2013 rate) and the mean cost per ICH hospital survivor was $94,856 (expressed in Canadian dollars at the 2017 rate, converts to €62,585 at the 2013 rate). We found similar results, as the mean cost per one-year ICH was €84,859 (expressed in euros at the 2013 rate) and 71,195 (expressed in euros at the 2013 rate), per one-year SAH survivor.
Regarding SAH, a study from the UK in 2001, showed that the cost per life saved was £40,816 (expressed in pounds sterling at the 2001 rate, converts to €82,546 at the 2013 rate) and the cost to avoid one bad outcome was £84,366 (expressed in pounds sterling at the 2001 rate, converts to €170,561 at the 2013 rate) [
23]. Quite similarly, the ECPS in our study was €71,195 (expressed in euros at the 2013 rate) but the ECPIS was markedly lower, being €96,265 (expressed at the 2013 rate). Another study from the UK reported that the estimated cost for treating one patient with SAH was £23,294 (expressed in pounds sterling at the 2005 rate, converts to €38,701 at the 2013 rate). This is somewhat lower than in our study, where the mean cost per patient with SAH was €51,906 (expressed in euros at the 2013 rate). Yet, the UK study did not include, for example, medication costs. In our study, the social security reimbursements were on average €9516 per patient with SAH, making the results between our study and the UK study very similar.
SAH was associated with the highest university hospital costs whereas AIS was associated with the lowest university hospital costs. In contrast to the other diagnostic group, most patients with SAH undergo extensive and costly treatments, including aneurysm clipping or endovascular treatment [
24]. The low university hospital costs in the AIS group may plausibly be explained by less severe illness (measured by the APACHE II and SAPS II), fewer patients being mechanically ventilated, shorter lengths of stay and lower treatment intensity (measured by the TISS-76). SAH, on the other hand, was associated with the highest treatment intensity and longest length of stay, leading to higher university hospital costs. This and our previous study provide good data on the cost-effectiveness of intensive care in TBI [
17]. Other TBI studies have identified total one-year direct and indirect costs between €16,579 and €35,560 (converted to euros at the 2013 rate) [
25‐
27] but data on cost-effectiveness are lacking.
An inbuilt study bias is that ICU admission criteria vary among the diagnostic groups included. For example, patients with SAH are preferably directly admitted to the ICU in some centers, independent of their level of consciousness, while patients with TBI, ICH or AIS can be treated outside of the ICU, given an adequate level of consciousness and appropriate radiological findings. Further, patient age is probably key in ICU selection criteria, as elderly patients with stroke are often excluded from aggressive ICU treatment. This may distort our results towards improved cost-effectiveness, as some patients are admitted due to an estimated favorable outcome. It should also be mentioned that some of the patients included might be admitted to ICU due to potential organ donation. The American Heart Association/American Stroke Association recommends full treatment for at least 2 days before implementing any treatment limitations [
28]. Organ donors often receive aggressive ICU treatment to uphold adequate organ vitality, which thus, is very resource-demanding as well. However, assessing the potential ICU treatment cost-effectiveness benefits of organ donation is out of the scope of this study.
We noted a marked decrease in unadjusted one-year mortality between 2007 and 2009. During the same years a substantial increase in patients admitted with ICH or AIS were noted due to structural changes in some centers leading to more less severely ill patients being admitted, which most likely explains the noted shift in mortality. It should also be highlighted that the vast majority of patients with ICH or AIS are treated outside of the ICU setting (for example in stroke units). In our study setting, only patients with the most severe cases of ICH and AIS are treated in the ICU, as all hospitals included have dedicated stroke units. Thus, our study obviously undervalues the total burden of AIS and ICH but represent the ICU-treated portion well. Furthermore, during the study period thrombectomy had not been established in the treatment of large vessel occlusion AIS [
29‐
33]. The patients with and large vessel occlusion AIS probably constitute a notable proportion of patients with AIS being treated in the ICU prior to the establishment of thrombectomy. Thus, considering the effectiveness of thrombectomy for large vessel occlusion, the long-term cost-effectiveness of AIS has most likely improved and the number of patients with AIS requiring ICU care at all have may have decreased [
34,
35]. This limits the interpretation and the generalization of the AIS results to the modern thrombectomy era. Cost-effectiveness correlated strongly with the severity of illness and the ECPIS was highest among patients with ICH or AIS in all risk bands, with the exception of risk band 4, where AIS was associated with the lowest ECPIS. Although we cannot confirm this, it is possible that these patients represent a group with relatively small infarcts but severe extracranial organ dysfunction (e.g. respiratory dysfunction after basilar artery occlusion), requiring intensive care, from which recovery is favorable.
Future directions
In our study we noted a steady increase in the number of neurocritical patients treated in the ICU. This probably reflects the parallel increase in ICU beds and the rapidly aging population in Finland, increasing the need for intensive care [
8]. The total number of ICU beds in Finland is approximately 6 per 100,000 persons, which is among the lowest in Europe and one fifth of that in the USA [
36,
37]. Thus, considering the rapidly aging population a continued increase in the number of patients requiring neurocritical care and an increased demand for ICU beds are to be expected. Accordingly, efforts should be put towards preventing these events, as outcomes are poor and treatment is resource-demanding and costly. Effectively treating risk factors for stroke (SAH, ICH, AIS) and TBI has the potential to reduce the burden of these neurocritical illnesses. For example, the decreased incidence of smoking in Finland has been linked to a decreased incidence in SAH [
38]. Similar prevention should be targeted in TBI, which could be achieved by avoiding falls among the elderly, and reducing alcohol-related falls and traffic-related accidents.
Strengths and limitations
This study was conducted in a government tax-funded healthcare system, where all citizens have the right to equal care, avoiding selection bias due to differences in access to treatment. Further, specialized neurointensive care has for decades been centralized to five university hospitals and, thus, the current study represents as good as the whole Finnish adult population. Moreover, data on rehabilitation hospital length of stay is electronically recorded on a national level by the Finnish National Institute for Health and Welfare, making this data extremely comprehensive. Another unique feature of this study is that in Finland, social security costs are essentially paid by one institution, Kela, which covers all Finnish citizens regardless of insurance status. Thus, in combination with the high-quality FICC database with the small number of missing patients, our study comprehensively catches the burden of neurocritical illnesses treated in the ICU in a developed country setting [
10].
Regarding patients with TBI or SAH, we were able to include four of five ICUs providing specialized intensive care for these patients, making the TBI and SAH largely representative of the whole Finnish population, although less so than for ICH and AIS. Yet, as already mentioned, not all patients with AIS or ICH are treated in the ICU. After the introduction of thrombectomy the number of patients with AIS requiring ICU care has probably decreased as well. The noted increase in AIS admissions in this study is due to a change in local policy in one of the hospitals leading to more patients with AIS with less severe illness being treated in the ICU, probably explaining the decrease in unadjusted mortality in the middle of the study period. Thus, clearly our results on patients with AIS or ICH cannot be generalized to patients being treated outside the ICU.
We used a surrogate marker of permanent disability, i.e. if the patient was granted a permanent disability allowance or disability pension by Kela. In comparison to other commonly used outcome scales (e.g. Glasgow Outcome Scale, modified Rankin Scale), our definition may include some degree in inaccuracy but considering that all Finnish citizens are covered by Kela we believe that our definition adequately reflects neurological outcome. Further, the FICC database does not contain uniformly standardized data on limitation of care from the beginning of the study period. Thus, some included patients are probably ICU-treated due to upcoming potential organ donation.
We did only study adult patients and, thus, our results cannot directly be generalized to the pediatric population. Further, we only included patients with TBI, ICH, SAH or AIS. Thus, other neurocritical illnesses, such as cerebral venous thrombosis, status epilepticus, bacterial meningitis, viral encephalitis and neuromuscular disorders were not included. Last, the study was conducted in a single Nordic country. Thus, our results are best applicable to settings with similar healthcare systems.