Assessing the Validity and Reproducibility of an Iron Dietary Intake Questionnaire Conducted in a Group of Young Polish Women

Abstract

The aim of the study was to analyse a designed brief iron dietary intake questionnaire based on a food frequency assessment (IRONIC-FFQ—IRON Intake Calculation-Food Frequency Questionnaire), including the assessment of validity and reproducibility in a group of 75 Polish women aged 20–30 years. Participants conducted 3-day dietary records and filled in the IRONIC-FFQ twice (FFQ1—directly after the dietary record and FFQ2—6 weeks later). The analysis included an assessment of validity (comparison with the results of the 3-day dietary record) and of reproducibility (comparison of the results obtained twice—FFQ1 and FFQ2). In the analysis of validity, the share of individuals correctly classified into tertiles was over 50% (weighted κ of 0.36), while analysis of correlation revealed correlation coefficients of almost 0.5. In the assessment of reproducibility, almost 80% of individuals were correctly classified and less than 3% were misclassified (weighted κ of 0.73), while a correlation coefficient higher than 0.85 was obtained. Both in the assessment of validity and of reproducibility, a Bland–Altman index of 6.7% was recorded (93.3% of compared pairs of results were in the acceptable range, attributed to differences within ± 2SD limit). Validation of the IRONIC-FFQ revealed a satisfactory level of validity and positively validated reproducibility.

Validity and Reproducibility of the Iodine Dietary Intake Questionnaire Assessment Conducted for Young Polish Women

“…The iodine-fortified salt, being the only iodine-fortified food product in Poland, obligatory since 1997 [ 22 ] was also included. The clustering procedure was conducted, similarly as in the previous studies [ 23 , 24 ], in order to obtain a lower number of items included in the questionnaire. The most popular serving sizes were determined on the basis of the Polish food model booklet [ 25 ] and verified by dietitian during the pilot research.…”

“…Individuals were asked about the exact number of servings of products from the groups specified in the IODINE-FFQ which had been consumed during a typical week throughout the previous year (open-ended question), similarly, as in the case of previous own studies conducted for vitamin D [ 23 ] and iron [ 24 ]. Such approach is associated with the fact, that the dietary intake may differ throughout the year that results from the seasonality [ 12 ].…”

“…Validation of the obtained IODINE-FFQ questionnaire was conducted according to the same methodology, as validations published previously [ 23 , 24 ]. It included an analysis of the validity (external validation comparing results of the FFQ1 and FFQ2 with results of the 3-day dietary record, whereas both assessments were conducted by the same researcher) and reproducibility of the method (internal validation comparing results obtained twice—FFQ1 and FFQ2, with both assessments conducted by the same researcher), as defined by Willett and Lenart [ 26 ].…”

<p>Effect of Integrated Pictorial Handbook Education and Counseling on Improving Anemia Status, Knowledge, Food Intake, and Iron Tablet Compliance Among Anemic Pregnant Women in Indonesia: A Quasi-Experimental Study</p>

“…We ranked the frequency of intake on a five-level scale: 5 indicated a frequency of more than once a day, 4 of at least once a day, 3 of 4-6 times per week, 2 of 2-3 times per week, and 1 of once a week or never. 26 Firstly, the FFQ consisted of 55 foods with iron content no lower than 0.1 mg per 100 g, 27 selected from the Indonesian food composition tables. 28 During the pre-test study, only 22 foods were reliable enough to be included in the final version of the questionnaire, with a Cronbach's alpha coefficient of 0.786.…”

Dietary Health-Related Risk Factors for Women in the Polish and Croatian Population Based on the Nutritional Behaviors of Junior Health Professionals

“…The assessment of the diet was based on a 3-day dietary record, according to widely applicable rules [46]. The dietary assessment was conducted by respondents during three random and nonconsecutive days, which were commanded to be typical and two of them were to be weekdays and one weekend day.…”