BackgroundDifferent instruments have been used to assess ability to perform everyday functional activities, such as activities of daily living (ADL) and instrumental activities of daily living (IADL). No measures of functional activity have been validated in cardiac surgery. We assessed the reliability and validity of the Standardized Assessment of Global activities in the Elderly (SAGE) scale.
MethodsWe undertook an observational sub-study of VISION Cardiac Surgery. Patients were assessed post-discharge after cardiac surgery using SAGE and comparator measures to determine convergent validity. A blinded independent assessor administered SAGE by phone within 7 days to determine test-retest reliability. We sought to demonstrate a correlation of ≥0.5 between SAGE and each corresponding measure. We also sought to define the SAGE score corresponding to severe functional disability, defined using the World Health Organisation Disability Assessment Schedule (WHODAS).
ResultsThere were 152 patients included. Inter-rater reliability was excellent (intra-class correlation coefficient=0.99; 95% confidence interval [CI], 0.98-0.99). Convergent validity was evident, ranging from adequate for the overall SAGE score (0.54; 95% CI, 0.42-0.65) to very good for the SAGE mobility sub-score (0.80; 95% CI, 0.73-0.85). SAGE was initially poorly correlated with the IADL index (-0.24) but increased to -0.60 after post-hoc adjustment of SAGE scoring. A SAGE score ≥7 was associated with severe functional disability and occurred in 42/152 (27.6%) of patients.
ConclusionThese results demonstrate the reliability and validity of the SAGE scale as a measure of global function in patients discharged home after cardiac surgery.
Clinical trial registrationNCT01842568.