The validity of self-reported use of health care across socioeconomic strata: a comparison of survey and registration data.

BACKGROUND Socioeconomic differences in health and in use of health care are well known. Most data on socioeconomic differences in health care utilization are based on retrospective self-report in community surveys, but the evidence on the validity of self-reported utilization of health care across socioeconomic groups is limited. The aim of this study was to assess the validity of self-reported utilization of health care across socioeconomic groups in the general population. METHODS We compared the concordance of self-reported and registered hospitalization (one year, n = 1277), and utilization of physiotherapy (one year, n = 1302) and use of prescription drugs (3 months, n = 899), by socioeconomic group (educational level, income, occupational status). Data came from a face-to-face health interview survey in Amsterdam and a health insurance register, and were limited to native Dutch and lower and middle income groups. RESULTS Concordance between reported and registered utilization was generally good to excellent; kappas (agreement adjusted for chance agreement) and percentage accurately reporting ranged from 0.60 and 80% (drugs) to 0.80 and 96% (hospitalization). They differed little, and without statistical significance, between people of low socioeconomic status and others. Assessment of socioeconomic groups in more detail yields somewhat more variation, but no systematic trend in concordance by higher socioeconomic status. CONCLUSION Self-report offers a reasonably valid estimate of differences in utilization of health care between socioeconomic groups in the general population, at least for lower and middle income groups.