Abstract
BACKGROUND: The validity of self-reported chronic conditions has been assessed by comparing them with medical records or register data in several studies. However, the reliability of self-reports of chronic diseases has less often been examined. Our aim was to assess the proportion and determinants of inconsistent self-reports of diabetes in a long panel study. METHODS: SHARE (Survey of Health, Ageing and Retirement in Europe) includes 140,000 persons aged ≥ 50 years from 28 European countries and Israel. We used data from waves 1 to 7 (except wave 3) collected between 2004 and 2017. Diabetes was assessed by self-report. An inconsistent report for diabetes was defined as reporting the condition in one wave, but denying it in at least one later wave. The analysis data set included 13,179 persons who reported diabetes, and answered the question about diabetes in at least one later wave. Log-binomial regression models were fitted to estimate crude and adjusted relative risks (RR) with 95% confidence intervals (CI) for the associations between various exposure variables and inconsistent report of diabetes. RESULTS: The proportion of persons with inconsistent self-reports of diabetes was 33.0% (95% CI: 32.2%-33.8%). Inconsistencies occurred less often in persons taking antidiabetic drugs (RR = 0.53 (0.53-0.56)), persons with BMI ≥ 35 kg/m(2) versus BMI < 25 kg/m(2) (RR = 0.70, (0.64-0.77)), and poor versus excellent subjective health (RR = 0.87 (0.75-1.01)). Inconsistencies occurred more often in older persons (RR = 1.15 (1.12-1.18) per 10 years increase of age), and persons not reporting their age at diabetes onset (RR = 1.38 (1.31-1.45)). CONCLUSION: In SHARE, inconsistent self-report of diabetes is frequent. Consistent reports are more likely for persons whose characteristics make diabetes more salient, like intake of antidiabetic medication, obesity, and poor subjective health. However, lack of attention in answering the questions, and poor wording of the items may also play a role.