Mismatches in health : a global analysis of discrepancies between self-reported and tested mobility and cognition

The health of individuals is frequently assessed based on self-reported information derived from surveys. However, self-reports are often inconsistent with their tested equivalents, indicating measurement issues. While discrepancies between self-reported and tested health indicators have been investigated for high-income countries in Europe, little comparative research has been conducted involving other low-income regions. This paper analyses discrepancies between self-reported and tested health limitations across 25 countries from six world regions with different income-levels, cultural backgrounds, institutional settings, and epidemiological trajectories. Using harmonised data from the Gateway to Global Aging, we match self-reported mobility and cognition with their tested equivalent to assess discrepancies at the individual level. Our results suggest that the consistency between these measures is strongly correlated with the Human Development Index, with lower scores of development showing higher discrepancies. Examining patterns by age reveals that self-reports do not accurately reflect the deterioration of health associated with aging - tested health exhibits a pronounced age gradient, whereas self-reported health varies little over the life course, particularly self-reported memory. We find no persistent gender differences in consistency. These discrepancies cast doubt on the reliability of mobility and cognitive self-reports, especially when comparing health across nations with differing development levels.