Assessing consent for and response to health survey components in an era of falling response rates: National Health and Nutrition Examination Survey, 2011-2018.

Response rates for national population-based surveys have declined, including the National Health and Nutrition Examination Survey (NHANES). Declining response to the initial NHANES interview may impact consent and participation in downstream survey components such as record linkage, physical exams, storage of biological samples and phlebotomy. Interview response rates dropped from 68% in 2011-2012 to 53% in 2017-2018 for adults age 18 and older. Response was higher for children (1-17 years) but with a similar downward trend (2011-2012, 81%; 2017-2018, 65%). Despite declining interview response rates, changes in consent and response rates for downstream components over time have been mixed. Among those interviewed, the examination response rate was over 93%, consent for record linkage was over 90%, and consent for storage of specimens for future research was over 99%. The availability of a blood sample for storage ranged between 60%-65% for children and 78%-85% for adults.