Statistical methods to assess and minimize the role of intra-individual variability in obscuring the relationship between dietary lipids and serum cholesterol

Liu, Kiang; Stamler, Jeremiah; Dyer, Alan R.; McKeever, J.; McKeever, Patricia

doi:10.1016/0021-9681(78)90004-8

Cited by 517 publications

(235 citation statements)

References 28 publications

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“…A number of studies have examined the relative contributions of several sources of variation in dietary data (Liu et al, 1978;Beaton et al, 1979;Rush & Kristal, 1982;McGee et al, 1982;Todd et al, 1983;Beaton et al, 1983;Hunt et al, 1983;Sempos et al, 1985;Tangney et al, 1987;McAvay & Rodin, 1988;Nelson et al, 1989;Hartman et al, 1990;Neuhaus et al, 1991;Wassertheil-Smoller et al, 1993). These investigations have generally compared the intra-and interindividual variations within a population, but no studies have reported the relative contribution of within-population and between-population variance to total variability between populations.…”

Section: Introductionmentioning

confidence: 99%

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

et al. 1998

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Objectives: To determine the extent to which interpopulation (between-population) variance, relative to intrapopulation (within-population) variance, contribute to the total variability in nutrient intakes. Design: Cross-sectional study. Setting: Five Public Health Center districts in Japan. Subjects: Two hundred and seven men and 183 spouses. Interventions: A three-day weighed food record. Main outcome measures: The total variance in the consumption of 17 nutrient variables was partitioned by analysis of variance into its inter-and intrapopulation components separately for men and women. Results: The percentage contribution of the interpopulation to total variance differed according to the nutrient; it was notable (8±17%) for total energy, carbohydrates, phosphorus, and sodium in both men and women, but was negligible (less than 4%) for micronutrients such as retinol, carotene, thiamin, ribo¯avin, niacin and ascorbic acid. The ratio of intra-to interpopulation variance was estimated for 31 nutrients (17 in men and 14 in women). The point estimates of the ratio were larger than unity in all nutrients, and the lower limit of the 95% con®dence intervals exceeded unity for all but 5 nutrients. Of the two sources of intrapopulation variation, intraindividual variance was larger than interindividual variance in most of the nutrient. Conclusions: The relative magnitude of interpopulation variation in dietary data can be used to quantify the range of exposure in ecological studies and to examine the heterogeneity of populations pooled for individualbased analysis.

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Section: Introductionmentioning

confidence: 99%

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

et al. 1998

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“…[6][7][8][9]39,[47][48][49] Hence the goal of dietary assessment had to be to approximate as closely as possible true intake of each individual participant for each of 4 days, and then use 4-day mean values for each person in analyses, thereby lessening the role of intraindividual variation in producing coefficients for nutrient-BP relations less than true values (the regression-dilution problem). [1][2][3][4][5][6][7][8] Multiple procedures, stipulated in the Protocol and Manuals of Operations, were implemented to accomplish the goal of collecting dietary data of high-order validity for each participant. All these sought to minimize known sources of error; for this purpose they drew upon experience of preceding studies and the literature on cognitive behaviour.…”

Section: Discussionmentioning

confidence: 99%

“…Single 24-h recalls are limited and generally inadequate for assessing the diet of individuals. [1][2][3][4][5][6][7][8] Multiple recalls enable measurement of intraindividual variability in nutrient intake, and use of mean values yields greater reliability for each person. They also reduce inter-individual measurement variability.…”

Section: Collection Of Dietary Datafprocess and Quality Controlmentioning

confidence: 99%

INTERMAP: the dietary data—process and quality control

et al. 2003

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The aim of this report is to describe INTERMAP standardized procedures for assessing dietary intake of 4680 individuals from 17 population samples in China, Japan, UK and USA: Based on a common Protocol and Manuals of Operations, standardized collection by centrally trained certified staff of four 24 h dietary recalls, two timed 24-h urines, two 7-day histories of daily alcohol intake per participant; tape recording of all dietary interviews, and use of multiple methods for ongoing quality control of dietary data collection and processing (local, national, and international); one central laboratory for urine analyses; review, update, expansion of available databases for four countries to produce comparable data on 76 nutrients for all reported foods; use of these databases at international coordinating centres to compute nutrient composition. Chinese participants reported 2257 foods; Japanese, 2931; and UK, 3963. In US, use was made of 17 000 food items in the online automated Nutrition Data System. Average time/ recall ranged from 22 min for China to 31 min for UK. Among indicators of dietary data quality, coding error rates (from recoding 10% random samples of recalls) were 2.3% for China, 1.4% for Japan, and UK; an analogous US procedure (re-entry of recalls into computer from tape recordings) also yielded low discrepancy rates. Average scores on assessment of taped dietary interviews were high, 40.4 (Japan) to 45.3 (China) (highest possible score: 48); correlations between urinary and dietary nutrient valuesFsimilar for men and womenF were, for all 4680 participants, 0.51 for total protein, range across countries 0.40-0.52; 0.55 for potassium, range 0.30-0.58; 0.42 for sodium, range 0.33-0.46. The updated dietary databases are valuable international resources. Dietary quality control procedures yielded data generally indicative of high quality performance in the four countries. These procedures were time consuming. Ongoing recoding of random samples of recalls is deemed essential. Use of tape recorded dietary interviews contributed to quality control, despite feasibility problems, deemed remediable by protocol modification. For quality assessment, use of correlation data on dietary and urinary nutrient values yielded meaningful findings, including evidence of special difficulties in assessing sodium intake by dietary methods.

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“…These were shown to be non-adjusted and adjusted for energy, according to the residual method proposed by Willett and Stampfer (1986). Taking into account the within-person variability present in the food intake quantified by the 4 days of 24 h dietary recalls, the within-and between-person variation components were determined, in order to 'de-attenuate' the coefficients of Pearson's correlation (Liu et al, 1978;Beaton et al, 1979Beaton et al, , 1983. For interpretation of correlation coefficients, the range from 0.4 to 0.7 was considered (Willett, 1998) as the acceptable reference for relative method validation.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…In the same way, the food intake variation has been studied by several authors (Liu et al, 1978;Beaton et al, 1979Beaton et al, , 1983Sempos et al, 1985;Basiotis et al, 1987;Nelson et al, 1997b;Willett, 1998), providing a better analysis of the estimates found in their components.…”

Section: Introductionmentioning

confidence: 99%

The influence of education in the validation process of a food frequency questionnaire for adults in Viçosa, Minas Gerais, Brazil

et al. 2006

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Objective: To evaluate the educational influence in the relative validation of a semiquantitative food frequency questionnaire (FFQs) for adults in the city of Viçosa, Brazil. Design and subjects: Four 24-h dietary recalls (reference method) were applied to a sample of 94 adults of both genders, at intervals of 1 month. At the end of the study, an FFQs consisting of 58 food items was also applied. Then, the individuals were divided into two main groups according to their educational level (lower and higher). The dietary data were calculated by the Diet Pro 4.0 software and analyzed according to differences of means or medians and Pearson's correlation coefficients. These coefficients were adjusted by the energy and corrected by the within-person variance for each educational group, considering the extreme quartiles of the data distribution. Results: The intake of energy and nutrients, based on the 24 h dietary recalls, was inferior for the lower educational group (Po0.05). For the FFQs, just the protein and calcium intakes were statistically different, suggesting interference of the education variable in this assessment. Overestimations in the FFQs were identified in the analyses of means and medians for vitamin C and retinol intakes in the lower education group and for retinol in the higher education one. However, when evaluated by correlation coefficients non-adjusted and adjusted, they were well correlated. On the other hand, lipid (r ¼ 0.34) and calcium (r ¼ 0.13) coefficients of the group with less instruction showed beneath the desirable values, suggesting weak consistence of the estimates provided by the FFQs for these nutrients. Correlation means of r ¼ 0.65 and 0.54 were found for the higher and lower educational groups, respectively. Conclusions:The results indicate that FFQs showed acceptable performance on evaluating the habitual food consumption for most of the nutrients in the studied population. A tendency for better quantifications in the groups with higher education was observed, inferring its influence in the assessment of the dietary intake. Sponsorship: CAPES -Coordenação de aperfeiçoamento de pessoal de nível superior.

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Statistical methods to assess and minimize the role of intra-individual variability in obscuring the relationship between dietary lipids and serum cholesterol

Cited by 517 publications

References 28 publications

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

INTERMAP: the dietary data—process and quality control

The influence of education in the validation process of a food frequency questionnaire for adults in Viçosa, Minas Gerais, Brazil

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