Six-Minute Walk Distance After Critical Illness: A Systematic Review and Meta-Analysis

Abstract

Background and Objectives: Impaired physical functioning is common and long lasting after an intensive care unit (ICU) admission. The 6-minute walk test (6MWT) is a validated and widely used test of functional capacity. This systematic review synthesizes existing data in order to: (1) evaluate 6-minute walk distance (6MWD) in meters over longitudinal follow-up after critical illness, (2) compare 6MWD between acute respiratory distress syndrome (ARDS) versus non-ARDS survivors, and (3) evaluate patient- and ICU-related factors associated with 6MWD. Data Sources: Five databases (PubMed, EMBASE, Cumulative Index of Nursing and Allied Health Literature, PsychINFO, and Cochrane Controlled Trials Registry) were searched to identify studies reporting 6MWT after hospital discharge in survivors from general (ie, nonspeciality) ICUs. The last search was run on February 14, 2018. Databases were accessed via Johns Hopkins University Library. Data Extraction and Synthesis: Pooled mean 6MWD were reported, with separate linear random effects models used to evaluate associations of 6MWD with ARDS status, and patient- and ICU-related variables. Twenty-six eligible articles on 16 unique participant groups were included. The pooled mean (95% confidence interval [CI]) 6MWD results at 3- and 12-months post discharge were 361 (321-401) and 436 (391-481) meters, respectively. There was a significant increase in 6MWD at 12 months compared to 3 months ( P = .017). In ARDS versus non-ARDS survivors, the mean (95% CI) 6MWD difference over 3-, 6-, and 12-month follow-up was 73 [13-133] meters lower. Female sex and preexisting comorbidity also were significantly associated with lower 6MWD, with ICU-related variables having no consistent associations. Conclusions: Compared to initial assessment at 3 months, significant improvement in 6MWD was reported at 12 months. Female sex, preexisting comorbidity, and ARDS (vs non-ARDS) were associated with lower 6MWT results. Such factors warrant consideration in the design of clinical research studies and in the interpretation of patient status using the 6MWT.

Predictive variables for poor long‐term physical recovery after intensive care unit stay: An exploratory study

“…Our finding that exercise capacity was limited at 3, 6, and 12 months after ICU discharge was similar to the results of Fan et al who reported impairment in 6MW distance in survivors after acute lung injury, 6 and also were comparable to the findings of Herridge et al in survivors of ARDS, one year after ICU discharge 33 . However, our findings identified more severe limitations in exercise capacity in women compared with men, which agrees with the findings of a recent systematic review and meta‐analysis reporting that the female gender was associated with shorter 6MW distances achieved after critical illness 34 . Furthermore, our women participants had lower self‐reported physical function (SF‐36v2 PF domain) at 3 and 6 months after ICU discharge than patients who were diagnosed with ICU‐AW during their ICU stays 17 .…”

“…33 However, our findings identified more severe limitations in exercise capacity in women compared with men, which agrees with the findings of a recent systematic review and meta-analysis reporting that the female gender was associated with shorter 6MW distances achieved after critical illness. 34 tion has been reported between male gender and greater physical recovery after ICU stay. 1,12 Also, an association has been reported between younger women with fewer days of sedation and greater physical recovery compared with three other trajectory groups.…”

Effect of in-bed cycling on acute muscle wasting in critically ill adults: A randomised clinical trial

“…The 6MWT was only completed once, without replication. Whilst this is common in studies involving critically ill patients [46], the potential feasibility or impact of learning effects of repeated 6MWT in hospital settings among critical illness survivors remains a priority for further research.…”

COVID-19 and Post-intensive Care Syndrome: Community-Based Care for ICU Survivors

“…Activity limitations commonly associated with PICS include limited exercise capacity, reduced gait speed, and problems with balance. 6,8 Exercise capacity, as measured by the Six Minute Walk Test (6MWT), is 55% to 84% of predicted or control group values during the first year following critical illness 6,25 and factors associated with reduced exercise capacity include female sex, presence of preexisting comorbidity, and history of acute respiratory distress syndrome. 25 The 6MWT is a robust outcome measure that had been validated for people following ICU care.…”

“…6,8 Exercise capacity, as measured by the Six Minute Walk Test (6MWT), is 55% to 84% of predicted or control group values during the first year following critical illness 6,25 and factors associated with reduced exercise capacity include female sex, presence of preexisting comorbidity, and history of acute respiratory distress syndrome. 25 The 6MWT is a robust outcome measure that had been validated for people following ICU care. 26,27 The 6MWT has been used to assess exercise capacity for people with PICS because of the availability of normative data from the general population that can be used for comparison.…”