BACKGROUND: Survey rates are known to decline
with age. Survey results can be affected by response
bias if nonresponders are more, or less, likely than
participants to suffer from the condition being
studied. For instance, it is possible that older
adults with dementia would be less likely to
participate in a study of dementing disorders.
METHODS: A random sample of a rural U.S.
population aged 65+ years yielded 1,422 participants
and 912 refusers in addition to others who were
ineligible, inaccessible, or untestable. Participants
and refusers were compared on age, sex, 5-year
mortality, and causes of death suggestive of dementia
as listed on death certificates.
RESULTS:
Compared to participants, refusers were significantly
older and more likely to be women, with mortality
similar to that of participants at approximately
5-year follow-up. Death certificate data revealed no
significant differences in reported causes of death
indicating or suggesting dementia.
CONCLUSIONS:
In this population, those who refused to participate
in a dementia survey were not more likely to be ill or
demented than those who did participate.