Comparison of performance-based and self-rated functional capacity in Spanish elderly.

Recent data have shown differences between Spain and the United States in the prevalence of reported disability among community elderly. Differences in reporting functional capacity by culture may contribute to these observed differences. The purpose of this study was to estimate the agreement between self-report of disability and performance-based measures for some basic mobility tasks in the community-dwelling elderly of a Mediterranean country. Interviews containing questions about difficulty for walking and rising from a chair, and performance-based measures (walking speed and chair stand tests) were carried out in 626 individuals aged 72 years and older in Barcelona, Spain. Kappa statistics were calculated, and logistic regression models were constructed to identify possible factors associated with under- and overreporting functional capacity. Moderate kappas (0.41-0.55) were found between self-report and performance-based measures. Patients who rated their health as "poor or very poor" were less likely to underreport disability (adjusted odds ratio (OR) = 0.2, 0.4) but more likely to overreport it (adjusted OR = 23.4, 9.9). No significant agreement differences by sex or informant source were found. These findings suggest that Spanish elderly self-report functional capacity accurately and that, contrary to previous results among US elderly, the direction of the observed disagreement is not systematic.