Outcome Measurement in ICU Survivorship Research From 1970 to 2013: A Scoping Review of 425 Publications*

Objectives: To evaluate the study designs and measurement instruments used to assess physical, cognitive, mental health, and quality of life outcomes of survivors of critical illness over more than 40 years old as a first step toward developing a core outcome set of measures for future trials to improve outcomes in ICU survivors. Design: Scoping review. Setting: Published articles that included greater than or equal to one postdischarge measure of a physical, cognitive, mental health, or quality of life outcome in more than or equal to 20 survivors of critical illness published between 1970 and 2013. Instruments were classified using the World Health Organization’s International Classification of Functioning, Disability, and Health framework. Subjects: ICU survivors. Interventions: None. Measurements and Main Results: We reviewed 15,464 abstracts, and identified 425 eligible articles, including 31 randomized trials (7%), 116 cross-sectional studies (27%), and 278 cohort studies (65%). Cohort studies had a median (interquartile range) sample size of 96 survivors (52–209), with 38% not fully reporting loss to follow-up. A total of 250 different measurement instruments were used in these 425 articles. Among eligible articles, 25 measured physical activity limitations (6%), 40 measured cognitive activity limitations (9%), 114 measured mental health impairment (27%), 196 measured participation restriction (46%), and 276 measured quality of life (65%). Conclusions: Peer-reviewed publications reporting patient outcomes after hospital discharge for ICU survivors have grown from 3 in the 1970s to more than 300 since 2000. Although there is evidence of consolidation in the instruments used for measuring participation restriction and quality of life, the ability to compare results across studies remains impaired by the 250 different instruments used. Most articles described cohort studies of modest size with a single follow-up assessment using patient-reported measures of participation restriction and quality of life. Development of a core outcome set of valid, reliable, and feasible measures is essential to improving the outcomes of critical illness survivors.