Difference in reported pre-morbid health-related quality of life between ARDS survivors and their substitute decision makers

Context: Substitute decision makers may consider the pre-morbid health status of their critically ill loved one when making treatment decisions on her/his behalf. Objective: To compare estimates of pre-morbid health-related quality of life (HRQOL) obtained from survivors of the acute respiratory distress syndrome (ARDS) with those of their substitute decision makers using the Short Form 36 (SF-36). Design: Prospective cohort study. Setting: University-affiliated intensive care unit in Toronto, Canada. Patients: A sample of 46 ARDS survivors and their substitute decision makers drawn from a previously described cohort. Interventions: We measured agreement and differences between responses on the SF-36 obtained from survivors (at 3 months after ICU discharge) and their substitute decision makers (at study entry). Measurements and results: Agreement was poor for all SF-36 components and differences reached significance in three domains. In multivariable analysis considering age; sex; Acute Physiology, Age, and Chronic Health Evaluation II score; and Lung Injury Score, only patient age was associated with the mean difference between estimates for the 'Mental Health' domain. On average, estimates of pre-morbid HRQOL obtained from substitute decision makers were lower than those obtained from survivors. Conclusions: Agreement between estimates of pre-morbid HRQOL provided by ARDS survivors and their substitute decision makers was poor. Compared with survivors, proxies tended to provide lower estimates of pre-morbid HRQOL. Substitute decision making for incapacitated patients is an imperfect process during which family members may underestimate their loved ones' own perception of pre-morbid health status. Alternatively, survivors of critical illness may overestimate pre-morbid HRQOL.