Validity and reliability of a new food frequency questionnaire compared to 24 h recalls and biochemical measurements: pilot phase of Golestan cohort study of esophageal cancer
A F Malekshah, M Kimiagar, M Saadatian-Elahi, A Pourshams, M Nouraie, G Goglani, A Hoshiarrad, M Sadatsafavi, B Golestan, A Yoonesi, N Rakhshani, S Fahimi, D Nasrollahzadeh, R Salahi, A Ghafarpour, S Semnani, J P Steghens, C C Abnet, F Kamangar, S M Dawsey, P Brennan, P Boffetta, R Malekzadeh, A F Malekshah, M Kimiagar, M Saadatian-Elahi, A Pourshams, M Nouraie, G Goglani, A Hoshiarrad, M Sadatsafavi, B Golestan, A Yoonesi, N Rakhshani, S Fahimi, D Nasrollahzadeh, R Salahi, A Ghafarpour, S Semnani, J P Steghens, C C Abnet, F Kamangar, S M Dawsey, P Brennan, P Boffetta, R Malekzadeh
Abstract
Background: A pilot study was carried out to evaluate validity and reproducibility of a food frequency questionnaire (FFQ), which was designed to be used in a prospective cohort study in a population at high risk for esophageal cancer in northern Iran.
Methods: The FFQ was administered four times to 131 subjects, aged 35-65 years, of both sexes. Twelve 24-h dietary recalls for two consecutive days were administered monthly during 1 year and used as a reference method. The excretion of nitrogen was measured on four 24-h urine samples, and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol was measured from two time points. Relative validity of FFQ and 24-h diet recall was assessed by comparing nutrient intake derived from both methods with the urinary nitrogen and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol.
Results: Correlation coefficients comparing energy and nutrients intake based on the mean of the four FFQ and the mean of twelve 24-h diet recalls were 0.75 for total energy, 0.75 for carbohydrates, 0.76 for proteins and 0.65 for fat. Correlation coefficients between the FFQ-based intake and serum levels of beta-carotene, retinol, vitamin C and vitamin E/alpha-tocopherol were 0.37, 0.32, 0.35 and 0.06, respectively. Correlation coefficients between urinary nitrogen and FFQ-based protein intake ranged from 0.23 to 0.35. Intraclass correlation coefficients used to measure reproducibility of FFQ ranged from 0.66 to 0.89.
Conclusion: We found that the FFQ provides valid and reliable measurements of habitual intake for energy and most of the nutrients studied.
Source: PubMed