Objectives: Many studies of socio-economic inequalities in the prevalence of chronic conditions rely on self-reports. For chronic nonspecific lung disease, heart disease, and diabetes mellitus, we studied the effects of misreporting on variations in prevalence rates by respondents' level of education.
Methods: In 1991, a health interview survey was conducted in the southeastern Netherlands with 2867 respondents. Respondents' answers were compared with validated diagnostic questionnaires in the same survey and the diagnoses given by the respondents' general practitioners.
Results: Misreporting of chronic lung disease, heart disease, and diabetes may be extensive. Depending on the condition and the reference data used, the confirmation fractions ranged between .61 and .96 and the detection fractions between .13 and .93. Misreporting varied by level of education, and although various patterns were observed, the dominant pattern was that of more underreporting among less educated persons. The effects on prevalence rates were to underestimate differences by level of education to a sometimes considerable degree.
Conclusions: Misreporting of chronic conditions differs by respondents' level of education. Health interview survey data underestimate socioeconomic inequalities in the prevalence of chronic conditions.