The decades from 1990 to 2010 saw a clinical and research focus on technical, pharmaceutical, and scientific advances in intensive care medicine, and the key question was “Will my patient survive or die?” More recent decades have focused on “How will my patient survive?”, and in consequence, many studies are investigating patient-centered outcomes after critical illness [1]. The adverse long-term outcomes are collectively known as post intensive care syndrome (PICS). In general, PICS refers to long-term physical, neurocognitive and psychiatric sequelae that adversely affect health-related quality of life (HRQL) and daily functioning [2]. The Center for Disease Control defines HRQL as ‘an individual’s (or a group’s) perceived physical and mental health over time’. HRQL is a multidimensional construct which can be individual, intimate and complex, and it may be nearly impossible to ‘press’ such a construct into a score or quantitative summary. Nevertheless, some important recent investigations have highlighted specific aspects of long-term outcome and HRQL after critical illness, and they have provided approaches for prevention or attenuation of long-term morbidities.

A recent review of patients who survive acute respiratory distress syndrome (ARDS) found a substantial reduction in HRQL (physical activity, depression, anxiety, post-traumatic stress disorder [PTSD], and vitality domains [3]); however, the reduction in HRQL was similar to that of patients surviving other critical illnesses. In a prospective 5-year longitudinal study in 196 ARDS survivors [4] 38% of patients had prolonged symptoms of anxiety, 32% depression and 23% PTSD. Further, worse pre-ARDS mental health was strongly associated with long-term psychiatric symptoms after ICU discharge. In consequence, a careful anamnesis of psychiatric history in ARDS patients may help identify patients at highest risk for prolonged psychiatric morbidity [5].

Comparable to ARDS, sepsis is a potentially life-threatening disease that challenges staff and is associated with high mortality and morbidity. Little data exist on HRQL in sepsis survivors. A recent study found significantly lower HRQL in physical and social functioning, role physical, general health, and vitality domains compared to United States population data [6]. Thompson et al. compared long-term outcomes of patients who survived sepsis with the outcome of non-septic critical illness survivors [7]. There were no significant differences in the number of reported problems with mobility (sepsis 37.8% vs. non-sepsis 38.7%, p = 0.86), ability to perform self-care (24.7% vs. 26.0%, p = 0.44), pain/discomfort (42.4% vs. 41.6%, p = 0.54) or anxiety/depression (36.9% vs. 37.7%, p = 0.68) at 6 months. In a qualitative study of HRQL, the sepsis survivors reported difficulties with psychological disorders, fatigue, physical impairment, coping with daily life, ability to walk, return to normal living, cognitive impairments, self-perception, and control over life [8].

We have limited information regarding risk factors for development of PICS and their relationship with HRQL in surviving ICU−patients. In a large French and European Outcome Registry in ICUs (FROG-ICU-study) Bastian et al. [9] investigated the influence of the socioeconomic status and deprivation on HRQL, depression, anxiety and PTSD in 1834 surviving ICU patients. Up to 31.6% of survivors presented symptoms of PTSD and 31.5% of survivors reported clinically meaningful symptoms of anxiety or depression. Quality-of-life scores were lower in the ICU survivors compared to the general French population. Patients who had lower socioeconomic status scored significantly lower on the Short Form-36 physical component scale (median 47.5, IQR 30−68.8) compared to patients without social deprivation [54.4, IQR (35−78.8); p = 0.010] and 32% in the non-deprived group and 15% in the deprived group had significant symptoms of PTSD. These findings suggest that increased awareness is warranted in terms of recognition of impaired physical activities in individuals with low socioeconomic status. Interventions to prevent or ameliorate adverse psychological outcomes (depression, anxiety, and PTSD) and improve quality of life are also needed.

Most critical illnesses result in inflammation which, per se, may contribute to neurologic complications. Hughes et al. investigated the relationships between a marker of the blood−brain barrier integrity (S100B), a marker of neuronal (Ubiquitin C-terminal hydrolase L1 [UCHL1]) and of endothelial (E-selectin) injury and long-term cognitive impairment, and the impact of inflammation on this relationship [10]. In 419 survivors of critical illness both S100B and E-selectin were associated with global cognitive impairment at 3 and 6 months after discharge, whereas for UCHL1 this association was only seen at 3 months. Some of these associations were modified by inflammation. These findings suggest that plasma biomarkers measured early in the ICU are associated with neuronal damage. This study also highlights a potential pathophysiologic relationship between inflammation and development of cognitive impairments.

The ability to return to work is a paramount contributor to quality of life, and many people experience ‘work’ not only as a necessity but as an important factor in self-realization and satisfaction. The inability to return to work is common after critical illness, and PICS morbidities are important impediments to return to work. A recent Danish register-based cohort study [11] found among 5762 ICU survivors that 68% had returned to work within 2 years of hospital discharge. Mechanical ventilation (HR 0.70, 95% CI 0.65−0.77) as well as longer ICU length of stay were significantly associated with a reduced chance to return to work. Furthermore, sick leave and receipt of disability pension were common in all surviving ICU patients. Similarly, a multicenter study in 923 ARDS survivors [12] found that 44% of patients employed prior to their critical illness were jobless at 12 months follow-up. After accounting for death and retirement only half returned to work by 12 months. Of the ARDS survivors 71% had lost earnings with a mean of $26,949 ± $22,447. Further, being non-white, having a longer hospital length of stay and older age were associated with joblessness. A study by Norman et al. [13] assessed the association between employment at 3 and 12 months after critical illness and global cognitive function. At 3 (62%) and 12 months (49%) follow-up a decrease in employment was observed and 47 and 49% of previously employed survivors were jobless. Cognitive impairments at 12 months were associated with unemployment.

In conclusion, important recent investigations have extended our knowledge regarding long-term outcomes and HRQL after critical illness (Table 1). These studies identified several risk factors (e.g., socioeconomic status, pre-ICU health and employment, markers of brain injury, intensity of organ support, and length of ICU-stay) for development of cognitive, psychological, and physical sequelae and reduced HRQL after ARDS or other critical illness. The development of more precise instruments to predict neuropsychological or physical morbidity is needed [14] and, in the future, studies surviving patient’s opinions regarding the decisions made during acute treatment should be integrated. In a prospective, longitudinal study conducted in 315 patients being weaned from prolonged ventilation at a long-term acute-care hospital [15] 84.7% of survivors indicated willingness to undergo mechanical ventilation again. Clinical investigations of the effects of various interventions, including new technologies (e.g., early neurocognitive rehabilitation software [16]) are urgently required to improve long-term outcome after critical illness.

Table 1 Risk factors for long-term adverse outcomes
Full size table