Comparison of self-reported and performance-based measures of functional ability in elderly patients in an emergency department: implications for selection of clinical outcome measures

BACKGROUND: Assessment of functional ability in elderly patients is often based on self-reported rather than performance-based measures. This study aims to compare self-reported and performance-based measures of functional ability in a population of elderly patients at an emergency department (ED). METHODS: Participants were 61 patients aged 65 years and above admitted to an ED. The self-reported measure used was the Barthel-20; the performance-based measures were Timed Up and Go (TUG); 30s-Chair Stand Test (30s-CST) and Assessment of Motor and Process Skills (AMPS) with the two scales; motor and process. Correlation analyses were conducted to examine the relationships between the self-reported and performance-based measures of functional ability. RESULTS: The correlation between the Barthel-20 and the TUG was moderate (r = −0.64). The correlation between the Barthel-20 and the AMPS motor was also moderate (r = 0.53). The correlation between the Barthel-20 and the 30s-CST was fair (r = 0.45). The correlation between Barthel-20 and the AMPS process was non-significant. The results were affected by high ceiling effect (Barthel-20). CONCLUSION: Self-reported and performance-based measures seem to assess different aspects of functional ability. Thus, the two methods provide different information, and this highlight the importance of supplementing self-reported measures with performance-based measures when assessing functional ability in elderly patients. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12877-016-0376-1) contains supplementary material, which is available to authorized users.