| 1. |
- Agogo, George O., et al.
(author)
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A method for sensitivity analysis to assess the effects of measurement error in multiple exposure variables using external validation data
- 2016
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In: BMC Medical Research Methodology. - : Springer Science and Business Media LLC. - 1471-2288. ; 16
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Journal article (peer-reviewed)abstract
- Background: Measurement error in self-reported dietary intakes is known to bias the association between dietary intake and a health outcome of interest such as risk of a disease. The association can be distorted further by mismeasured confounders, leading to invalid results and conclusions. It is, however, difficult to adjust for the bias in the association when there is no internal validation data. Methods: We proposed a method to adjust for the bias in the diet-disease association (hereafter, association), due to measurement error in dietary intake and a mismeasured confounder, when there is no internal validation data. The method combines prior information on the validity of the self-report instrument with the observed data to adjust for the bias in the association. We compared the proposed method with the method that ignores the confounder effect, and with the method that ignores measurement errors completely. We assessed the sensitivity of the estimates to various magnitudes of measurement error, error correlations and uncertainty in the literature-reported validation data. We applied the methods to fruits and vegetables (FV) intakes, cigarette smoking (confounder) and all-cause mortality data from the European Prospective Investigation into Cancer and Nutrition study. Results: Using the proposed method resulted in about four times increase in the strength of association between FV intake and mortality. For weakly correlated errors, measurement error in the confounder minimally affected the hazard ratio estimate for FV intake. The effect was more pronounced for strong error correlations. Conclusions: The proposed method permits sensitivity analysis on measurement error structures and accounts for uncertainties in the reported validity coefficients. The method is useful in assessing the direction and quantifying the magnitude of bias in the association due to measurement errors in the confounders.
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| 2. |
- Freisling, Heinz, et al.
(author)
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Main nutrient patterns are associated with prospective weight change in adults from 10 European countries
- 2016
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In: European Journal of Nutrition. - : Springer. - 1436-6207 .- 1436-6215. ; 55:6, s. 2093-2104
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Journal article (peer-reviewed)abstract
- PURPOSE: Various food patterns have been associated with weight change in adults, but it is unknown which combinations of nutrients may account for such observations. We investigated associations between main nutrient patterns and prospective weight change in adults.METHODS: This study includes 235,880 participants, 25-70 years old, recruited between 1992 and 2000 in 10 European countries. Intakes of 23 nutrients were estimated from country-specific validated dietary questionnaires using the harmonized EPIC Nutrient DataBase. Four nutrient patterns, explaining 67 % of the total variance of nutrient intakes, were previously identified from principal component analysis. Body weight was measured at recruitment and self-reported 5 years later. The relationship between nutrient patterns and annual weight change was examined separately for men and women using linear mixed models with random effect according to center controlling for confounders.RESULTS: Mean weight gain was 460 g/year (SD 950) and 420 g/year (SD 940) for men and women, respectively. The annual differences in weight gain per one SD increase in the pattern scores were as follows: principal component (PC) 1, characterized by nutrients from plant food sources, was inversely associated with weight gain in men (-22 g/year; 95 % CI -33 to -10) and women (-18 g/year; 95 % CI -26 to -11). In contrast, PC4, characterized by protein, vitamin B2, phosphorus, and calcium, was associated with a weight gain of +41 g/year (95 % CI +2 to +80) and +88 g/year (95 % CI +36 to +140) in men and women, respectively. Associations with PC2, a pattern driven by many micro-nutrients, and with PC3, a pattern driven by vitamin D, were less consistent and/or non-significant.CONCLUSIONS: We identified two main nutrient patterns that are associated with moderate but significant long-term differences in weight gain in adults.
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| 3. |
- Skeie, Guri, et al.
(author)
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Intake of whole grains and incidence of oesophageal cancer in the HELGA Cohort
- 2016
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In: European Journal of Epidemiology. - : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 31:4, s. 405-414
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Journal article (peer-reviewed)abstract
- Few prospective studies have investigated the association between whole-grain consumption and incidence of oesophageal cancer. In the Scandinavian countries, consumption of whole grains is high and the incidence of oesophageal cancer comparably low. The aim of this paper was to study the associations between consumption of whole grains, whole-grain products and oesophageal cancer, including its two major histological subtypes. The HELGA cohort is a prospective cohort study consisting of three sub-cohorts in Norway, Sweden and Denmark. Information regarding whole-grain consumption was collected through country-specific food frequency questionnaires. Cancer cases were identified through national cancer registries. Cox proportional hazards ratios were calculated in order to assess the associations between whole grains and oesophageal cancer risk. The analytical cohort had 113,993 members, including 112 cases, and median follow-up time was 11 years. When comparing the highest tertile of intake with the lowest, the oesophageal cancer risk was approximately 45 % lower (adjusted HR 0.55, 95 % CI 0.31-0.97 for whole grains, HR 0.51, 95 % CI 0.30-0.88 for whole-grain products). Inverse associations were also found in continuous analyses. Whole-grain wheat was the only grain associated with lower risk (HR 0.32, 95 % CI 0.16-0.63 highest vs. lowest tertile). Among whole-grain products, the results were less clear, but protective associations were seen for the sum of whole-grain products, and whole-grain bread. Lower risk was seen in both histological subtypes, but particularly for squamous cell carcinomas. In this study, whole-grain consumption, particularly whole-grain wheat, was inversely associated with risk of oesophageal cancer.
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