The aim of the present study was to assess reproducibility and relative validity of a self-administered FFQ used in the PREDIMED Study, a clinical trial for primary prevention of CVD by Mediterranean diet in a population at high cardiovascular risk. The FFQ was administered twice (FFQ1 and FFQ2) to explore reproducibility at 1 year. Four 3 d dietary records (DR) were used as reference to explore validity; participants therefore recorded their food intake over 12 d in the course of 1 year. The degree of misclassification in the FFQ was also evaluated by a contingency table of quintiles comparing the information from the FFQ2 and the DR. A total of 158 men and women (aged 55– 80 years) were asked not to modify their dietary habits during the study period. Reproducibility for food groups, energy and nutrient intake, explored by the Pearson correlation coefficient (r) ranged 0·50– 0·82, and the intraclass correlation coefficient (ICC) ranged from 0·63 to 0·90. The FFQ2 tended to report higher energy and nutrient intake than the DR. The validity indices of the FFQ in relation to the DR for food groups and energy and nutrient intake ranged (r) from 0·24 to 0·72, while the range of the ICC was between 0·40 and 0·84. With regard to food groups, 68– 83 % of individuals were in the same or adjacent quintile in both methods, a figure which decreased to 55– 75 % for energy and nutrient intake. We concluded that FFQ measurements had good reproducibility and a relative validity similar to those of FFQ used in other prospective studies. Validity: Reproducibility: FFQ: Dietary records: Mediterranean population: PREDIMED Study: Spain

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Relative validity of a semi-quantitative food-frequency questionnaire in an elderly Mediterranean population of Spain.

Worldwide globalization and Westernization in social and economic aspects have led to drastic changes in South Korea during the past several decades. These changes include individual health behaviours, which were reflected as increased prevalence of non-communicable chronic diseases (NCDs), such as type 2 diabetes mellitus (T2DM), hypertension, obesity and cardiovascular disease (CVD). These NCDs are known to be caused by both environmental risk factors and predisposing genetic factors. Population decline is another issue in South Korea; the recorded fertility rate was 1.3 births per woman, and 10% of the population were elderly individuals aged 65 years according to the Population and Housing Census results of 2005-2010. We have also been observing an increased influx and efflux of the population due to globalization. In particular, there has been a rising tendency in the marriage-based inflow of South Asian women during the last decade. To attempt to solve public health issues resulting from these population trends and prepare for personalized and preventive health care in the future, the Korean government (National Research Institute of Health (NIH), Centers for Disease Control and Prevention and the Ministry of Health and Welfare, Korea) initiated a large prospective cohort study with government funding, named the Korean genome and epidemiology study (KoGES). The study is a consortium project consisting of six prospective cohort studies that would be categorized into population-based and geneenvironment model studies (Figure 1). The aim of the KoGES was to establish a genome epidemiological study platform for the research community with a health database and biobank, to investigate the genetic and environmental aetiology of common complex diseases in Koreans (i.e. T2DM, hypertension, obesity, metabolic syndrome, osteoporosis, CVD,and cancer) and causes of death with longterm follow-up. The ultimate goal of the KoGES was to develop comprehensive and applicable health care guidelines for common complex diseases in Koreans, reduce the burden of chronic diseases and improve the quality of life.

Cohort Profile: The Korean Genome and Epidemiology Study (KoGES) Consortium

Background Accurate values are a must in medicine. An important parameter in determining the quality of a medical instrument is agreement with a gold standard. Various statistical methods have been used to test for agreement. Some of these methods have been shown to be inappropriate. This can result in misleading conclusions about the validity of an instrument. The Bland-Altman method is the most popular method judging by the many citations of the article proposing this method. However, the number of citations does not necessarily mean that this method has been applied in agreement research. No previous study has been conducted to look into this. This is the first systematic review to identify statistical methods used to test for agreement of medical instruments. The proportion of various statistical methods found in this review will also reflect the proportion of medical instruments that have been validated using those particular methods in current clinical practice. Methodology/Findings Five electronic databases were searched between 2007 and 2009 to look for agreement studies. A total of 3,260 titles were initially identified. Only 412 titles were potentially related, and finally 210 fitted the inclusion criteria. The Bland-Altman method is the most popular method with 178 (85%) studies having used this method, followed by the correlation coefficient (27%) and means comparison (18%). Some of the inappropriate methods highlighted by Altman and Bland since the 1980s are still in use. Conclusions This study finds that the Bland-Altman method is the most popular method used in agreement research. There are still inappropriate applications of statistical methods in some studies. It is important for a clinician or medical researcher to be aware of this issue because misleading conclusions from inappropriate analyses will jeopardize the quality of the evidence, which in turn will influence quality of care given to patients in the future.

https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0037908&type=printable

Statistical Methods Used to Test for Agreement of Medical Instruments Measuring Continuous Variables in Method Comparison Studies: A Systematic Review

The food frequency questionnaire (FFQ) has been used as an important dietary assessment tool in epidemiologic studies, but the usefulness of the FFQ has been debated in recent years. This study was performed to evaluate the relative validities of 3-day food records and the semi-quantitative FFQ. A total of 124 subjects finished 3-day food records (FRs) during each of the four seasons, as well as the FFQ from December 2002 to May 2004. The FFQ was a food based semi-quantitative FFQ including 103 items. Three-day FRs from each season and a randomly selected season were compared with the remaining 9-day FRs. The remaining 9-day FRs, as a reference measurement, were also compared with the FFQ. Pearson’s correlation coefficients between the 3-day FRs and the 9-day FRs were between 0.14 and 0.56. Pearson’s correlation coefficients between the FFQ and the 9-day FRs ranged between 0.07 and 0.41. Average proportions of classification into the same quartiles, adjacent quartiles, and distant quartiles between the 3-day FRs and the 9-day FRs were 35.8%, 40.5%, and 5.2%, respectively. On average, the proportions of classification into the same quartiles, adjacent quartiles, and distant quartiles between the FFQ and the 9-day FRs were 31.1%, 39.4%, and 6.9%, respectively. Three-day FRs showed higher correlations and higher agreement proportions of quartile classification with the 9-day FRs than did the FFQ, but both relative validities of 3-day FRs and the FFQ appear to be acceptable as dietary assessment tools. Further studies for validating food intake by reliable biomarkers are necessary.

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Relative validities of 3-day food records and the food frequency questionnaire

https://www.journal-of-hepatology.eu/article/S0168-8278(15)00473-0/pdf

Relationship of Sitting Time and Physical Activity With Non-Alcoholic Fatty Liver Disease

Validation and reproducibility of food frequency questionnaire for Korean genome epidemiologic study

Youngchang Joo

Papers

Validation and reproducibility of food frequency questionnaire for Korean genome epidemiologic study.