In our study, we showed that the absence of rehabilitation for elderly ICU patients was associated with a 2.4 higher risk of decreased autonomy at 6 months after admission. We also provided a descriptive overview of the physical therapy performed in the ICU participating in the study.
Rehabilitation in intensive care unit
In their one-day prevalence study in 2011, Nydahl et al. have found that 77% of ICU patients were not mobilized out of bed, and that a very low proportion of patients were standing or walking outside of their bed (4%)[12]. Another study, performed in 2014 on adult patient with acute respiratory failure, has revealed that only a third of patients benefited from physical therapy[13]. Patients benefiting from physical therapy were more likely progress out of bed[13].
In their randomized controlled trial, Scweicker et al. have showed that a strategy of whole-body rehabilitation (physical and occupational therapy in the earliest days of critical illness; interruption of sedation) was associated with a better functional outcome at hospital discharge, a shorter duration of delirium, and more numerous ventilator-free days[7]. In their before/after study, Needham et al. have showed that, with the use of a quality improvement program focusing on reducing deep sedation and increasing the number of rehabilitation sessions (by increasing the number of therapists), the delirium, and physical and functional mobility were improved and associated with a shorter length of stay[2]. Needless to say, rehabilitation also increases the quality of life and patient’s mood during the ICU stay, because the ability to go out of bed represents a recovery of autonomy and a landmark for patients, as they do not need to rely entirely on nurses for every activity[6]. Some study have also reported the interest of “intensive rehabilitation” compared to “standard rehabilitation”: for example, the EPICC multicenter randomized controlled trial has reported no benefit of the intensive rehabilitation compared with standard care regarding the 6-month physical function[14]. Likewise, Maffei et al. have not reported any significant benefit of intensive rehabilitation for ICU patients admitted for liver transplant. However, there is still no conclusive evidence regarding the benefit for patients of rehabilitation therapy in itself during intensive care stay. A 2018 Cochrane review has concluded that there is insufficient evidence to concluded on the effect of early mobilization on critical care patients and had encouraged further studies to investigate this topic.
Regarding the definition of the rehabilitation, several options are offered to clinicians. For example, there is the possibility to use the ICU Mobility Scale[15]: ranging from 0 to 10, this 11-level scale allows clinicians to evaluate daily the intensity of the rehabilitation[16]. Paton et al. have used the highest Intensive Care Mobility Scale Level achieved during the length of stay as a predictor of quality of life. In our study, we choose a simpler criterion (“Out of bed during the ICU stay”) because it represents the goal of rehabilitation (i.e. standing and walking before hospital discharge). This is an objective that has been used repeatedly in published studies. However, neither the use of the ICU mobility scale nor our criterion provide an accurate representation of rehabilitation. Indeed, they do not take into account the duration of the ICU stay, the possibility (or not) to be rehabilitated, or the duration of the rehabilitation performed. Future studies should focus on the rehabilitation as a multivariable endpoint, including the intensity of rehabilitation, the number of rehabilitation sessions, the length of ICU stay, and the possibility (or not) to be rehabilitated.
Prediction of the 6-month disability
Studies focusing on the predictor of the 6-month disability are rare. In our final model, we included rehabilitation, diagnosis category, and baseline CFS. Recently, Higgins et al. have modeled the presence of new disability or death post-ICU stay[8]. In their final model, not surprisingly, the APACHE III score and the age were predictors of their composite outcome, as they are well-known predictors of mortality. By focusing solely on the presence of decreased autonomy among elderly survivors, age was not associated with the risk of presenting a new disability in our study. However, frailty was included in the final model, confirming the importance of a specific evaluation of elderly patients during their ICU stay. Indeed, in the study of Nakajima et al., CFS was associated with mobility impairment at ICU discharge in septic patients receiving early rehabilitation[17].
In their recent systematic review, Haines et al. have identified only two studies focusing of the development of model to predict the physical function post-ICU discharge. Detsky et al. have found that the APACHE III score, being a medical patient, older age, nonwhite race, recent hospitalization, prior transplantation, and history of cancer or of neurologic or liver disease were predictors of patients not returning to their baseline status at 6 months[9]. In another study from Schandl et al. focusing on the 2-month new onset disability, 4 predictors have been identified: low educational level, impaired core stability, fractures, and ICU length of stay longer than 2 days. Interestingly, the authors did not include in the variable selection process the frailty of patients, but their final model included the impaired core stability and the presence of fractures, which are probably highly collinear with frailty.
Studying the impact of rehabilitation
While several cohort studies have tried to demonstrate the benefit of rehabilitation during the ICU stay, the researcher community face several issues regarding the collinearity between the rehabilitation and the mortality.
Indeed, the most stable patients will benefit from early physical therapy and will most likely have a low mortality rate. On the other hand, unstable patients (too severe or too unstable) have a high mortality rate and cannot benefit from rehabilitation, thus leading to a bias regarding rehabilitation. There is also a competing risk between the intensity of rehabilitation (number of sessions) and the length of ICU stay, as patients in ICU for a short length of stay and displaying favorable outcome will benefit from a limited number of physical therapy sessions, and patients in ICU for longer durations and presenting multiple complications will benefit from a higher number of physical therapy sessions but still display an unfavorable outcome.