TY - JOUR
T1 - Use of a food frequency questionnaire to screen for dietary eligibility in a randomized cancer prevention phase III trial
AU - Ritenbaugh, Cheryl
AU - Aickin, Mikel
AU - Taren, Douglas
AU - Teufel, Nicolette
AU - Graver, Ellen
AU - Woolf, Kathleen
AU - Alberts, David S.
PY - 1997
Y1 - 1997
N2 - Cancer prevention clinical trials use food frequency questionnaires (FFQs) to assist in eligibility screening. FFQ reliability and validity studies are available, but these studies do not evaluate FFQs as screening tools. The Wheat Bran Fiber Trial of the University of Arizona used a FFQ as an eligibility screen with the goal of screening out subjects whose true daily calcium intake was less than 500 mg per day (for safety) and whose true dietary fiber intake was greater than 30 g per day (for safety and trial efficiency). Subjects ineligible by FFQ were interviewed for final dietary eligibility determinations. A study was undertaken within the Wheat Bran Fiber Trial to evaluate the sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of the FFQ used in this context. Four-day food records were collected on 183 potential participants before entry into the study. Using the 4-day averages as the 'true' value, sensitivity, specificity, positive predictive value, and NPV were calculated for men and women separately under two screening conditions: using the target calcium and dietary fiber values and using 'revised' values identified in interim analysis within the study. NPV was acceptable in all analyses. Sensitivity for low calcium intake was inadequate under the original criteria (0.33 for men and 0.09 for women) but acceptable under the revised criteria (0.80 for men and 0.81 for women). With the revised criteria, specificity declined, resulting in heavy screening burdens deemed worthwhile for the safety considerations. Dietary fiber eligibility screening worked well at target values. These differences were not predicted by reliability/validity studies.
AB - Cancer prevention clinical trials use food frequency questionnaires (FFQs) to assist in eligibility screening. FFQ reliability and validity studies are available, but these studies do not evaluate FFQs as screening tools. The Wheat Bran Fiber Trial of the University of Arizona used a FFQ as an eligibility screen with the goal of screening out subjects whose true daily calcium intake was less than 500 mg per day (for safety) and whose true dietary fiber intake was greater than 30 g per day (for safety and trial efficiency). Subjects ineligible by FFQ were interviewed for final dietary eligibility determinations. A study was undertaken within the Wheat Bran Fiber Trial to evaluate the sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of the FFQ used in this context. Four-day food records were collected on 183 potential participants before entry into the study. Using the 4-day averages as the 'true' value, sensitivity, specificity, positive predictive value, and NPV were calculated for men and women separately under two screening conditions: using the target calcium and dietary fiber values and using 'revised' values identified in interim analysis within the study. NPV was acceptable in all analyses. Sensitivity for low calcium intake was inadequate under the original criteria (0.33 for men and 0.09 for women) but acceptable under the revised criteria (0.80 for men and 0.81 for women). With the revised criteria, specificity declined, resulting in heavy screening burdens deemed worthwhile for the safety considerations. Dietary fiber eligibility screening worked well at target values. These differences were not predicted by reliability/validity studies.
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M3 - Article
C2 - 9149895
AN - SCOPUS:0030912867
SN - 1055-9965
VL - 6
SP - 347
EP - 354
JO - Cancer Epidemiology Biomarkers and Prevention
JF - Cancer Epidemiology Biomarkers and Prevention
IS - 5
ER -