Disability in activities of daily living, depression, and quality of life among older medical ICU survivors: a prospective cohort study

BACKGROUND Accurate measurement of quality of life in older ICU survivors is difficult but critical for understanding the long-term impact of our treatments. Activities of daily living (ADLs) are important components of functional status and more easily measured than quality of life (QOL). We sought to determine the cross-sectional associations between disability in ADLs and QOL as measured by version one of the Short Form 12-item Health Survey (SF-12) at both one month and one year post-ICU discharge. METHODS Data was prospectively collected on 309 patients over age 60 admitted to the Yale-New Haven Hospital Medical ICU between 2002 and 2004. Among survivors an assessment of ADL's and QOL was performed at one month and one-year post-ICU discharge. The SF-12 was scored using the version one norm based scoring with 1990 population norms. Multivariable regression was used to adjust the association between ADLs and QOL for important covariates. RESULTS Our analysis of SF-12 data from 110 patients at one month post-ICU discharge showed that depression and ADL disability were associated with decreased QOL. Our model accounted for 17% of variability in SF12 physical scores (PCS) and 20% of variability in SF12 mental scores (MCS). The mean PCS of 37 was significantly lower than the population mean whereas the mean MCS score of 51 was similar to the population mean. At one year mean PCS scores improved and ADL disability was no longer significantly associated with QOL. Mortality was 17% (53 patients) at ICU discharge, 26% (79 patients) at hospital discharge, 33% (105 patients) at one month post ICU admission, and was 45% (138 patients) at one year post ICU discharge. CONCLUSIONS In our population of older ICU survivors, disability in ADLs was associated with reduced QOL as measured by the SF-12 at one month but not at one year. Although better markers of QOL in ICU survivors are needed, ADLs are a readily observable outcome. In the meantime, clinicians must try to offer realistic estimates of prognosis based on available data and resources are needed to assist ICU survivors with impaired ADLs who wish to maintain their independence. More aggressive diagnosis and treatment of depression in this population should also be explored as an intervention to improve quality of life.