Do income questions and seeking consent to link medical records reduce survey response rates? A randomised controlled trial among older people.

Traditional measures of socioeconomic status may not be reliable for older people and income may be a useful measure for research into inequalities in health. At the same time, researchers increasingly wish to link survey findings to individual data taken from medical records. For this, consent must be sought. To examine whether questions on household income and seeking consent for medical record linkage affected response rates, a postal health survey of patients aged 65 to 74 was undertaken in an inner London practice. The overall response rate was 62.8%. In this study, the inclusion of an income question or seeking consent to access medical records did not reduce response rates to a health survey among older people.