The 131st Annual Meeting (November 15-19, 2003) of APHA

Abstract #56766

Quanhe Yang and J. David Erickson. National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention (CDC), 4770 Buford Hwy MS F-45, Chamblee, GA 30341, (770) 488-7186, qyang@cdc.gov

Background: The intake of synthetic folic acid is the most important predictor of blood folate concentration among nonpregnant women, but the reporting of folic acid-containing supplements use is subject to error. Objective: We assessed the effect of reporting error of folic acid-containing supplements use on blood folate concentrations. Design: Data from the Third National Health and Nutrition Examination Survey (NHANES III) were analyzed. We included all nonpregnant women aged 15-44 years. Respondents of NHANES III were asked twice about use of supplements, i.e., during household interview to recall use in the previous month and during physical examination to recall use in the last 24 hours. In order to examine the effect of error reporting, we classified women into five groups according to their use of folic acid-containing supplements in the previous month and 24 hours before physical examination: 1. nonuser; 2. <400ug daily user and not taken in last 24 hours; 3. <400ug daily user and taken in last 24 hours; 4. >=400ug daily user and not taken in last 24 hours; and 5. >=400ug daily user and taken in last 24 hours. We expected nonappreciable differences in red blood cell (RBC) folate concentration by status of 24-hour recall within same category of previous-month use because RBC folate reflects long-term average consumption. We calculated covariate-adjusted means of serum and RBC folate concentrations by these categories. Results: Among women who reported average daily use of >=400ug folic acid in the previous month, the adjusted mean RBC folate was 436.5 nmol/L(95% CI, 406.7-466.3 nmol/L) among nonusers in the last 24 hours and 519.7 nmol/L (95% CI, 496.2-543.2 nmol/L) among users in the last 24 hours (p<0.01). The significant difference in adjusted mean RBC folate by the status of last 24-hour recall of supplements use indicates an apparently erroneous reporting of daily supplements use in the previous month by some participants. Conclusions: The effect of reporting error of supplements use on blood folate concentrations is important in interpreting survey results, evaluating health education campaigns, and identifying populations who need special education programs.

Learning Objectives:

At the conclusion of the session, the participant (learner) in this session will be able to:
• have a better understanding of the effects of reporting error of folic acid supplements use on blood folate concentrations among reproductive aged women.
• check the possible errors of the self-reported behavior and the potential influence of these errors on the studied outcome variables in their own research.
• learn how to adjust the influence of reporting errors.

Keywords: Epidemiology, Women's Health

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.