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ORGETFULNESSWe use HRS self-reports and linked Medicare claims to look at a potential source of false negatives in surveys: negative replies to diabetes self-reports due to forgetfulness in old age. If older respondents have an accumulation of comorbidities and age-related changes in memory, they could forget about a diabetes diagnosis. If that were the case, we hypothesize that older respondents such as those considered in this study would report having the disease less so than can be identified in claims (as was documented in Figure 1), and do so increasingly with age.
In Figure A3 (Supplemental Digital Content 2), we find evidence in HRS supporting this notion. The gap between claims and self-reports is 4.4 percentage points in the youngest respondents in our sample (those aged 67-74), and 5.8 percentage points in respondents aged 85 and older. The difference-in-difference (the higher gap for older respondents) corresponds to 24%
of the difference in diabetes prevalence between claims and self-reports at ages 85 and over. That value is substantial and means we cannot rule out that measurement error due to forgetfulness contributes to the difference between self-reports and claims. As shown in Figure A4, ACS are also more prevalent in claims than heart attacks in self-reports for the older age groups, but the differences are not significant.
We cannot assert that forgetfulness caused the gaps at older ages. For instance, if doctor diagnose diseases differently at older ages, CCW algorithms may over-identify diseases differentially at older ages. Similarly, if CCW algorithms were to falsely identify diseases in patients with more claims, they would be more likely to do so for older people—who use health care services more frequently and thus have more claims. Additional research to investigate the impact of forgetfulness should investigate whether objective measures of cognition and memory impact concordance of self-reports with claim.
Also, our data do not allow us to investigate if respondents aged 67-74 display higher gaps in diabetes prevalence than younger age groups. Therefore, we cannot determine if forgetfulness
can on its own account for a large share of the differences between self-reports and claims. If this source of measurement issue was restricted to the population over 85 years old, for instance, the impact of forgetfulness would be too small to account for an important portion of observed differences.
