a1 School of Psychology, University of Adelaide, Adelaide, South Australia, Australia
a2 CSIRO Food and Nutritional Sciences, PO Box 10041, Adelaide, South Australia 5000, Australia
a3 Centre for Innovation in Cancer, Flinders University, School of Medicine, Adelaide, South Australia, Australia
Objective To demonstrate test–retest reliability (reproducibility) of a new self-administered lifetime diet questionnaire, with a focus on foods relevant to cognitive health in older age.
Design The reproducibility of dietary recall over four or five life periods was assessed by administering the questionnaire at two time points to an older cohort. The period between questionnaire administrations was 7 weeks. Polychoric correlations measured the association between recall at time 1 and time 2 and the weighted κ statistic measured the level of recall agreement for food groups across the two administrations of the questionnaire.
Setting Adelaide, South Australia.
Subjects Fifty-two cognitively healthy, older-age, community-dwelling adults completed the Lifetime Diet Questionnaire; mean age 81·8 (sd 4·4) years, range 70–90 years.
Results The questionnaire showed very good reproducibility in this sample with a mean polychoric correlation coefficient of 0·81 between administration at time 1 and time 2, and an average weighted κ of 0·49 for the level of recall agreement between food groups.
Conclusions The demonstrated reliability of this lifetime diet questionnaire makes it a useful tool to assess potential relationships between long-term dietary intake and later-age cognitive outcomes.
(Received February 10 2010)
(Accepted October 07 2010)
(Online publication December 21 2010)