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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Sustainable development of agriculture: contribution of farm-level assessment tools
Olde, Evelien de - \ 2017
University. Promotor(en): Imke de Boer, co-promotor(en): Eddy Bokkers; F.W. Oudshoorn. - Wageningen : Wageningen University - ISBN 9789463430685 - 152
sustainable agriculture - sustainability - sustainability indicators - sustainability criteria - assessment - tools - reliability - validity - farming systems - duurzame landbouw - duurzaamheid (sustainability) - duurzaamheidsindicatoren - duurzaamheidscriteria - beoordeling - gereedschappen - betrouwbaarheid - geldigheid - bedrijfssystemen

Current environmental, economic and social challenges urge agriculture to change to more sustainable modes of production. Insight in the impact of a system or a potential innovation on sustainability could support decision makers in identifying actions towards sustainable development. Over the past decade, therefore, a large number of tools have been developed to assess sustainability performance at farm level. Several concerns, however, have been raised whether assessment results provide reliable and valid conclusions about the sustainability performance of farms, and whether these conclusions can be implemented in practice. To evaluate the contribution of farm-level assessment tools to sustainable development of agriculture, this thesis analyzed current approaches to assessing sustainability. One of these approaches is the sustainability assessment tool RISE 2.0, which was used to assess the sustainability performance of 37 organic farms in Denmark. Analysis of the assessment results showed the impact of decisions, made during the development of a tool (e.g. selection of themes, indicators, reference values, scoring and aggregation method), on the assessment results. This emphasizes the importance of transparency in sustainability assessment tools to understand assessment results and identify actions to improve. Subsequently, a comparison of sustainability assessment tools in practice was made to gain insight into practical requirements, procedures and relevance perceived by farmers. Of 48 indicator-based sustainability assessment tools, only four tools (RISE, SAFA, PG and IDEA) complied to the selection criteria and were applied to assess the sustainability performance of five Danish farms. Characteristics including data requirements, assessment time, complexity, transparency and output accuracy varied between tools. Critical factors in farmers’ perception of tool relevance were context specificity, user-friendliness, complexity of the tool, language use, and a match between value judgements of tool developers and farmers. Farmers, moreover, indicated that implementing conclusions derived from sustainability assessments is challenging given the complex organization of agricultural systems. A more in-depth analysis of the four tools revealed a high diversity in selected indicators, themes, reference values, and scoring and aggregation methods. This results in different conclusions on the sustainability performance of farms, which does not only cause confusion but also affects the trust in, and reliability and implementation of, sustainability assessments. Variability in tools is caused by different perspectives on how to assess sustainability and is related to differences in context, priorities and value judgements of tool developers. These differences also play a role in the prioritization of criteria for indicator selection. To explore whether sustainability experts agreed on which criteria are most important in the selection of indicators and indicators sets for sustainability assessments, two ranking surveys were carried out. Both surveys showed a lack of consensus amongst experts about how best to measure agricultural sustainability. This thesis revealed variability in approaches to assess sustainability at farm level. This makes current assessment tools less suitable for functions that require a high reliability and validity, such as certification. Instead, current assessment tools present a useful starting point for discussion, reflection and learning on sustainable development of farming. To enhance the contribution of tools towards sustainable development of agriculture, more attention should be paid to increasing reliability and validity of tools, and improving transparency, harmonization, participation and implementation of assessments.

Statistical modelling for exposure measurement error with application to epidemiological data
Agogo, G.O. - \ 2016
University. Promotor(en): Hendriek Boshuizen; Fred van Eeuwijk, co-promotor(en): Hilko van der Voet. - Wageningen : Wageningen University - ISBN 9789462576223 - 160 p.
calibration - regression analysis - exposure assessment - validity - simulation models - statistical bias - epidemiology - kalibratie - regressieanalyse - blootstellingsbepaling - geldigheid - simulatiemodellen - statistische vertekening - epidemiologie

Background Measurement error in exposure variables is an important issue in epidemiological studies that relate exposures to health outcomes. Such studies, however, usually pay limited attention to the quantitative effects of exposure measurement error on estimated exposure-outcome associations. Therefore, the estimators for exposure-outcome associations are prone to bias. Existing methods to adjust for the bias in the associations require a validation study with multiple replicates of a reference measurement. Validation studies with multiple replicates are quite costly and therefore, in some cases only a single–replicate validation study is conducted besides the main study. For a study that does not include an internal validation study, the challenge in dealing with exposure measurement error is even bigger. The challenge is how to use external data from other similar validation studies to adjust for the bias in the exposure-outcome association. In accelerometry research, various accelerometer models have currently been developed. However, some of these new accelerometer models have not been properly validated in field situations. Despite the widely recognized measurement error in the accelerometer, some accelerometers have been used to validate other instruments, such as physical activity questionnaires, in measuring physical activity. Consequently, if an instrument is validated against the accelerometer, and the accelerometer itself has considerable measurement error, the observed validity in the instrument being validated will misrepresent the true validity.

Methodology In this thesis, we adapted regression calibration to adjust for exposure measurement error for a single-replicate validation study with zero-inflated reference measurements and assessed the adequacy of the adapted method in a simulation study. For the case where there is no internal validation study, we showed how to combine external data on validity for self-report instruments with the observed questionnaire data to adjust for the bias in the associations caused by measurement error in correlated exposures. In the last part, we applied a measurement error model to assess the measurement error in physical activity as measured by an accelerometer in free-living individuals in a recently concluded validation study.

Results The performance of the proposed two-part model was sensitive to the form of continuous independent variables and was minimally influenced by the correlation between the probability of a non-zero response and the actual non-zero response values. Reducing the number of covariates in the model seemed beneficial, but was not critical in large-sample studies. We showed that if the confounder is strongly linked with the outcome, measurement error in the confounder can be more influential than measurement error in the exposure in causing the bias in the exposure-outcome association, and that the bias can be in any direction. We further showed that when accelerometers are used to monitor the level of physical activity in free-living individuals, the mean level of physical activity would be underestimated, the associations between physical activity and health outcomes would be biased, and there would be loss of statistical power to detect associations.

Conclusion The following remarks were made from the work in this thesis. First, when only a single-replicate validation study with zero-inflated reference measurements is available, a correctly specified regression calibration can be used to adjust for the bias in the exposure-outcome associations. The performance of the proposed calibration model is influenced more by the assumption made on the form of the continuous covariates than the form of the response distribution. Second, in the absence of an internal validation study, carefully extracted validation data that is transportable to the main study can be used to adjust for the bias in the associations. The proposed method is also useful in conducting sensitivity analyses on the effect of measurement errors. Lastly, when “reference” instruments are themselves marred by substantial bias, the effect of measurement error in an instrument being validated can be seriously underestimated.

Measurement errors in dietary assessment using duplicate portions as reference method
Trijsburg, L.E. - \ 2016
University. Promotor(en): Pieter van 't Veer; Anouk Geelen; Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789462576421 - 128 p.
diet studies - nutritional assessment - questionnaires - reference standards - correction factors - validity - body mass index - regression analysis - food intake - food - protein - potassium - sodium - energy intake - methodology - dieetstudies - voedingstoestandbepaling - vragenlijsten - referentienormen - correctiefactoren - geldigheid - quetelet index - regressieanalyse - voedselopname - voedsel - eiwit - kalium - natrium - energieopname - methodologie

Measurement errors in dietary assessment using duplicate portions as reference method

Laura Trijsburg

Background: As Food Frequency Questionnaires (FFQs) are subject to measurement error, associations between self-reported intake by FFQ and outcome measures should be corrected for measurement error with data from a reference method. Whether the correction is adequate depends on the characteristics of the reference method used in the validation study. The duplicate portion method (DP), compared to the often used 24h recall (24hR), seems a promising reference method as correlated errors between FFQ and DP, such as memory bias, errors in portion size estimations and food composition databases, are not expected.

Aim: This thesis aimed to determine the validity of the DP compared to the 24hR as a reference method for FFQ validation. The second aim was to explore the validity of nutrient densities for DP, 24hR and FFQ. The third aim was to determine the factors associated with misreporting of energy, protein and potassium as estimated by DP, 24hR and FFQ.

Methods: Within the DuPLO-study, a Dutch validation study which is part of the NQplus study, two DPs, two FFQs, two blood and urinary biomarkers and one to fifteen 24hRs (web-based and/or telephone-based) were collected in 198 subjects, within 1.5 years. Also, one or two doubly labelled water measurements were available for 69 participants. Multivariate measurement error models were used to assess proportional scaling bias, error correlations with the FFQ, validity coefficients and attenuation factors. Furthermore linear regression analysis was used to determine the association between misreporting and various factors.

Results: The DP was less influenced by proportional scaling bias, had lower correlated errors with the FFQ and showed higher attenuation factors than the 24hR for potassium, sodium and protein. Also, the DP seemed a better reference method than the 24hR for the assessment of validity coefficients for the FFQ for various fatty acids. The attenuation factors for the FFQ, using either the DP or 24hR as reference method, agreed reasonably well. Furthermore, the DP showed, when using plasma fatty acids as reference, slightly better ranking of participants according to their intake of n-3 fatty acids (0.33) and the n‑3/LA ratio (0.34) than the 24hR (0.22 and 0.24, respectively). Less group level bias was observed for protein and sodium densities compared to their absolute intakes for FFQ, 24hR and DP, but not for potassium. Overall the validity coefficients and attenuation factors for DP, 24hR and FFQ did not improve for nutrient densities compared to absolute intakes, except for the attenuation factor for sodium density. Lastly, BMI proved to be the most consistent determinant associated with misreporting (group level bias) of energy, protein and potassium for DP, 24hR and FFQ. Men tended to underreport protein by the DP, FFQ and 24hR and persons of older age underreported potassium but only by the 24hR and FFQ. Other explorative determinants did not show a consistent association with misreporting of energy or nutrients by the different dietary assessment methods.

Conclusion: With respect to error correlations and attenuation factors the DP performed slightly better than the 24hR as a reference method for validating FFQs in epidemiological research. Furthermore, the use of nutrient densities does not necessarily improve the validity of the dietary intake estimates from DP, 24hR and FFQ. Moreover, it was shown that BMI is an important determinant of misreporting of energy, protein and potassium for these three assessment methods.

Performance of raters to assess locomotion in dairy cattle
Schlageter Tello, A.A. - \ 2015
University. Promotor(en): Peter Groot Koerkamp, co-promotor(en): Kees Lokhorst; Eddy Bokkers. - Wageningen : Wageningen University - ISBN 9789462572751 - 162
melkvee - voortbeweging - mankheid - voetziekten - beoordeling - gang - lichaamshouding - diergezondheid - methodologie - geldigheid - melkveehouderij - dairy cattle - locomotion - lameness - foot diseases - assessment - gait - posture - animal health - methodology - validity - dairy farming


Locomotion scoring systems are procedures used to evaluate the quality of cows’ locomotion. When scoring locomotion, raters focus their attention on gait and posture traits that are described in the protocol. Using these traits, raters assign a locomotion score to cows according to a pre-determined scale. Locomotion scoring systems are mostly used to classify cows as lame or non-lame. A preselected threshold within the scale determines whether a cow is classified as lame or non-lame. Since lameness is considered an important problem in modern dairy farming evaluation of locomotion scoring systems is utmost important. The objective of this thesis was to evaluate the performance of raters to assess locomotion in dairy cattle in terms of reliability (defined as the ability of a measuring device to differentiate among subjects) and agreement (defined as the degree to which scores or ratings are identical). This thesis also explores possibilities for the practical application of locomotion scoring systems. In a literature review comprising 244 peer-reviewed articles, twenty-five locomotion scoring systems were found. Most locomotion scoring systems varied in the scale used and traits observed. Some of the most used locomotion scoring systems were poorly evaluated and, when evaluated, raters showed an important variation in reliability and agreement estimates. The variation in reliability and agreement estimates was confirmed in different experiments aiming to estimate the performance of raters for scoring locomotion and traits under different practical conditions. For instance, experienced raters obtained better intrarater reliability and agreement when locomotion scoring was performed from video than by live observation. In another experiment, ten experienced raters scored 58 video records for locomotion and for five different gait and posture traits in two sessions. A similar number of cows was allocated in each level of the five-level scale for locomotion scoring. Raters showed a wide variation in intra- and interrater reliability and agreement estimates for scoring locomotion and traits, even under the same practical conditions. When agreement was calculated for specific levels when scoring locomotion and traits, the lowest agreement tended to be in level 3 of a five-level scale. When a multilevel scale was transformed into a two-level scale, agreement increased, however, this increment was likely due to chance. The variation in reliability and agreement is explained by different factors such as the lack of a standard procedure for assessing locomotion or the characteristics of the population sample that is assessed. The factor affecting reliability and agreement most, however, is the rater him/herself. Although the probability for obtaining acceptable reliability and agreement levels increases with training and experience, it is not possible to assure that raters score cows consistently in every scoring session. Given the large variation in reliability and agreement, it can be concluded that raters have a moderate performance to assess consistently locomotion in dairy cows. The variable performance of raters when assessing locomotion limits the practical utility of locomotion scoring systems as part of animal welfare assessment protocols or as golden standard for automatic locomotion scoring systems.

The Development of a Diet Quality Score for Preschool Children and Its Validation and Determinants in the Generation R Study
Voortman, T. ; Kiefte-de Jong, J.C. ; Geelen, A. ; Villamor, G.B. ; Moll, H.A. ; Jongste, J.C. de; Raat, H. ; Hofman, A. ; Jaddoe, V.W.V. ; Franco, O.H. ; Hooven, E.H. van den - \ 2015
The Journal of Nutrition 145 (2015)2. - ISSN 0022-3166 - p. 306 - 314.
healthy eating index - multiple imputation - measurement error - pattern-analysis - food - adolescents - associations - childhood - nutrition - validity
Background: Although many studies have examined health effects of infant feeding, studies on diet quality shortly after the weaning and lactation period are scarce. Objectives: Our aims were to develop and evaluate a diet score that measures overall diet quality in preschool children and to examine the sociodemographic and lifestyle determinants of this score. Methods: On the basis of national and international dietary guidelines for young children, we developed a diet score containing 10 components: intake of vegetables; fruit; bread and cereals; rice, pasta, potatoes, and legumes; dairy; meat and eggs; fish; oils and fats; candy and snacks; and sugar-sweetened beverages. The total score ranged from 0 to 10 on a continuous scale and was standardized to an energy intake of 1200 kcal/d with the residual method. The score was evaluated in 3629 children participating in the Generation R Study, a population-based prospective cohort study. Food consumption was assessed with a food-frequency questionnaire (FFQ) at a median age of 13 mo. Results: The mean +/- SD diet score was 4.1 +/- 1.3. The food-based diet score was positively associated with intakes of many nutrients, including n-3 (omega-3)-31 fatty acids [FAs; 0.25 SD increase 195% CI: 0.22, 0.27) per 1 point increase in the diet score], dietary fiber [0.32 (95% CI: 0.30, 0.34)], and calcium [0.13 (95% CI: 0.11, 0.16)], and was inversely associated with intakes of sugars [-0.28(95% CI: -0.31, -0.26)] and saturated fat [-0.03 (95% CI: -0.05, -0.01)]. A higher diet score was associated with several health-conscious behaviors, such as maternal folic acid supplement use during pregnancy, no smoking during pregnancy, and children watching less television. Conclusion: We developed a novel food-based diet score for preschool children that could be applied in future studies to compare diet quality in early childhood and to investigate associations between diet in early childhood and growth, health, and development.
Determinants of maternal fetal attachment in women from a community-based sample
Maas, A.J.B.M. ; Vreeswijk, C.M.J.M. ; Braeken, J. ; Vingerhoets, A.J.J.M. ; Bakel, H.J.A. van - \ 2014
Journal of Reproductive and Infant Psychology 32 (2014)1. - ISSN 0264-6838 - p. 5 - 24.
prenatal attachment - antenatal attachment - child characteristics - personality - pregnancy - representations - temperament - variables - validity - behavior
BackgroundMaternal fetal attachment (MFA) has been found to be an important predictor for the developing relationship between mother and child. During the last decades, research on determinants of MFA has yielded inconclusive and even contradictory results. Until now, a process model in which multiple determinants of MFA are studied concurrently has been lacking. The present study evaluates a process model (based on Belsky's model of parenting) in which the specific contributions of parental, contextual, and expected child characteristics to MFA were examined.MethodsParticipants, 351 pregnant women from a community-based sample, completed questionnaires concerning their personality, attachment security, partner support, perceived stress, expected child temperament, and MFA at 26 weeks gestational age. Based on Belsky's model, a set of competing structural equation models were formulated and evaluated with path analysis.ResultsMFA was found to be multiply determined by parental, contextual, and expected child characteristics. These factors explained 19% of the variance in MFA. Pregnant women who were more extrovert, conscientious and agreeable reported having higher levels of MFA. In contrast, those women who perceived more stress and expected having an infant with a dull temperament reported lower levels of MFA.ConclusionThis study demonstrated that the theoretical framework of Belsky's model is applicable for explaining variations in the quality of the mother-fetus relationship in the pregnancy period. More knowledge of the determinants of MFA could help to identify mothers at risk for developing suboptimal feelings of attachment.
The impact of the means of context evocation on consumers' emotion associations towards eating occasions
Piqueras Fiszman, B. ; Jaeger, S.R. - \ 2014
Food Quality and Preference 37 (2014). - ISSN 0950-3293 - p. 61 - 70.
evoked consumption contexts - imagery - appropriateness - responses - questionnaires - satisfaction - attributes - experience - validity - ratings
The joint investigation of the product, the consumer, and the consumption context is necessary for furthering the understanding of eating occasions (snacks and main meals), including their construction and enjoyment. The study of people’s experience of eating occasions is less advanced than the understanding of acceptability, preference, and choice of individual food/beverage items and/or their combination in meals. The current research contributes to narrowing this gap by focusing on emotions as a dimension of eating experiences and enjoyment. Under evoked consumption contexts (breakfast, lunch, afternoon snack, dinner), the emotion associations for several products (potato crisps, chocolate brownie, and kiwifruit) were obtained from consumers (n = 399) using a questionnaire method. Emotion associations were explored in relation to: (1) the way in which the food stimulus was evaluated by participants (tasting food vs. seeing a food image); (2) the serving presentation of the food stimulus (image of food shown in isolation vs. image of food served on a plate with cutlery); and (3) the means in which the consumption context was evoked (written vs. written and pictorial). Consumers’ product emotion associations when tasting a food stimulus vs. seeing an image of the same food were highly similar. There was some evidence that more specific means of presenting the food stimuli (with tableware vs. without tableware) and consumption contexts (written and pictorially vs. written only) influenced perceived appropriateness of the product in the focal consumption context. This resulted, for example, in a higher frequency of use of negative emotion terms in the less appropriate consumption contexts. Overall, through the use of evoked consumption contexts this research has contributed new understanding of product-specific emotional associations during eating occasions from a methodological approach. In addition to the aforementioned results a more general finding was the apparent reliance by participants on past product experiences when completing the emotion questionnaire.
Method validation study on determination of melamine and cyanuric acid in food : CEN Collaborative Study 2014 : Melamine and cyanuric acid
Elbers, I.J.W. ; Traag, W.A. - \ 2014
Wageningen : RIKILT Wageningen UR (RIKILT report 2014.014) - 6
melamine - methodologie - triazinen - voedselveiligheid - geldigheid - standaardisering - voedselbesmetting - methodology - triazines - food safety - validity - standardization - food contamination
At the request of the European Committee for Standardization (CEN) by RIKILT a standard for the determination of melamine (MEL) and cyanuric acid (CYA) in food was described. In order to validate this new CEN method a ring trial was organized between February 2014 and July 2014. The objective is to assess the comparability of results of melamine and cyanuric acid obtained by the new draft CEN standard in seven samples of food.
Measurement in interdisciplinary research: The contributions of widely-defined measurement and portfolio representations
Tobi, H. - \ 2014
Measurement 48 (2014). - ISSN 0263-2241 - p. 228 - 231.
soft systems - validity
An area of application of measurement with increasing relevance to science and society is interdisciplinary research. Measurement in interdisciplinary research poses new challenges to the theory of measurement, especially when scientists with different disciplinary cultures collaborate. A common framework that allows and invites communication about the process of measurement, including the content and form of the entities under study, is needed. The present paper aims to contribute to such a framework by operational widelydefined measurement and how the portfolio representation of measurement fits within operational widely-defined measurement and supports measurement of the kind of complex attributes often investigated in interdisciplinary research.
Healthy diet indicator and mortality in Eastern European populations: prospective evidence from the HAPIEE cohort
Stefler, D. ; Pikhart, H. ; Jankovic, N. ; Kubinova, R. ; Pajak, A. ; Malyutina, S. ; Simonova, G. ; Feskens, E.J.M. ; Peasey, A. ; Bobak, M. - \ 2014
European Journal of Clinical Nutrition 68 (2014). - ISSN 0954-3007 - p. 1346 - 1352.
food-frequency questionnaire - coronary-heart-disease - physical-activity - risk-factors - elderly-men - carotenoids - biomarkers - nutrition - validity - quality
Background/Objectives: Unhealthy diet has been proposed as one of the main reasons for the high mortality in Central and Eastern Europe (CEE) and the former Soviet Union (FSU) but individual-level effects of dietary habits on health in the region are sparse. We examined the associations between the healthy diet indicator (HDI) and all-cause and cause-specific mortality in three CEE/FSU populations. Subjects/Methods: Dietary intakes of foods and nutrients, assessed by food frequency questionnaire in the Health, Alcohol and Psychosocial Factors in Eastern Europe (HAPIEE) cohort study, were used to construct the HDI, which follows the WHO 2003 dietary recommendations. Among 18¿559 eligible adult participants (age range: 45–69 years) without a history of major chronic diseases at baseline, 1209 deaths occurred over a mean follow-up of 7 years. The association between HDI and mortality was estimated by Cox regression. Results: After adjusting for covariates, HDI was inversely and statistically significantly associated with cardiovascular disease (CVD) and coronary heart disease (CHD) mortality, but not with other cause-specific and all-cause mortality in the pooled sample. Hazard ratios per one standard deviation (s.d.) increase in HDI score were 0.95 (95% confidence interval=0.89–1.00, P=0.068), 0.90 (0.81–0.99, P=0.030) and 0.85 (0.74–0.97, P=0.018) for all-cause, CVD and CHD mortality, respectively. Population attributable risk fractions for low HDI were 2.9% for all-cause, 14.2% for CVD and 10.7% for CHD mortality. Conclusions: These findings support the hypothesis that unhealthy diet has had a role in the high CVD mortality in Eastern Europe.
Proficiency test for tropane alkaloids in food en feed
Pereboom-de Fauw, D.P.K.H. ; Elbers, I.J.W. ; Mulder, P.P.J. ; Nijs, W.C.M. de - \ 2014
Wageningen : RIKILT Wageningen UR (RIKILT report 2014.008) - 35
voer - voedsel - voedselproducten - geldigheid - betrouwbaarheid - laboratoriummethoden - graansoorten - voedselconsumptie - voedselveiligheid - tropaanalkaloïden - feeds - food - food products - validity - reliability - laboratory methods - cereals - food consumption - food safety - tropane alkaloids
Proficiency testing is conducted to provide laboratories with a powerful tool to evaluate and demonstrate the reliability of the data that are produced. Next to validation and accreditation, proficiency testing is an important requirement of the EU Additional Measures Directive 93/99/EEC [1] and is required by ISO 17025:200. The proficiency test for tropane alkaloids was organized by RIKILT, Wageningen UR in accordance with ISO 17043. The primary goal of this study was to provide laboratories with the opportunity to implement a method in their laboratory and to evaluate or demonstrate their performance regarding quantitative analysis of tropane alkaloids in cereals intended for human consumption and in animal feed.
Estimating the mediating effect of different biomarkers on the relation of alcohol consumption with the risk of type 2 diabetes
Beulens, J.W.J. ; Schouw, Y.T. van der; Moons, K.G.M. ; Boshuizen, H.C. ; A, D.L. van der; Groenwold, R.H.H. - \ 2013
Annals of Epidemiology 23 (2013)4. - ISSN 1047-2797 - p. 193 - 197.
coronary-heart-disease - food frequency questionnaire - high-density-lipoprotein - myocardial-infarction - postmenopausal women - insulin sensitivity - epic-nl - moderate - metaanalysis - validity
Purpose Moderate alcohol consumption is associated with a reduced type 2 diabetes risk, but the biomarkers that explain this relation are unknown. The most commonly used method to estimate the proportion explained by a biomarker is the difference method. However, influence of alcohol–biomarker interaction on its results is unclear. G-estimation method is proposed to accurately assess proportion explained, but how this method compares with the difference method is unknown. Methods In a case–cohort study of 2498 controls and 919 incident diabetes cases, we estimated the proportion explained by different biomarkers on the relation between alcohol consumption and diabetes using the difference method and sequential G-estimation method. Results Using the difference method, high-density lipoprotein cholesterol explained the relation between alcohol and diabetes by 78% (95% confidence interval [CI], 41–243), whereas high-sensitivity C-reactive protein (-7.5%; -36.4 to 1.8) or blood pressure (-6.9; -26.3 to -0.6) did not explain the relation. Interaction between alcohol and liver enzymes led to bias in proportion explained with different outcomes for different levels of liver enzymes. G-estimation method showed comparable results, but proportions explained were lower. Conclusions The relation between alcohol consumption and diabetes may be largely explained by increased high-density lipoprotein cholesterol but not by other biomarkers. Ignoring exposure–mediator interactions may result in bias. The difference and G-estimation methods provide similar results.
Factors influencing assessment quality in higher vocational education
Baartman, L. ; Gulikers, J.T.M. ; Dijkstra, A. - \ 2013
Assessment & Evaluation in Higher Education 38 (2013)8. - ISSN 0260-2938 - p. 978 - 997.
assessing professional competence - argument-based approach - validity - validation - performance
The development of assessments that are fit to assess professional competence in higher vocational education requires a reconsideration of assessment methods, quality criteria and (self)evaluation. This article examines the self-evaluations of nine courses of a large higher vocational education institute. Per course, 4–11 teachers and 3–10 students participated. The purpose of this article is to critically examine the quality of assessment in higher vocational education, to identify critical factors influencing assessment quality and to study whether self-evaluation leads to concrete points for improvement. Results show that strong points are fitness for purpose, comparability and fairness. Weak points are reproducibility of decisions and development of self-regulated learning. Critical factors are the translation of competences into assessment criteria to be used in daily lessons and the involvement of the work field. The self-evaluations generated many points for improvement, but not all were translated into actions. Altogether, this article provides a rich picture of assessment quality in higher education and identifies quality aspects that need improvement, (partly) confirming other research on current assessment methods.
Dietary Supplement Use and Colorectal Adenoma Risk in Individuals with Lynch Syndrome: The GEOLynch Cohort Study
Heine-Bröring, R.C. ; Winkels, R.M. ; Botma, A. ; Duijnhoven, F.J.B. van; Jung, A.Y. ; Kampman, E. - \ 2013
PLoS One 8 (2013)6. - ISSN 1932-6203
cancer - prevention - validity - families - vitamin - gene - omega-3-fatty-acids - questionnaire - metaanalysis - population
Background and Aims: Individuals with Lynch syndrome have a high lifetime risk of developing colorectal tumors. In this prospective cohort study of individuals with Lynch syndrome, we examined associations between use of dietary supplements and occurrence of colorectal adenomas. Materials and Methods: Using data of 470 individuals with Lynch syndrome in a prospective cohort study, associations between dietary supplement use and colorectal adenoma risk were evaluated by calculating hazard ratios (HR) and 95% confidence intervals (CI) using cox regression models adjusted for age, sex, and number of colonoscopies during person time. Robust sandwich covariance estimation was used to account for dependency within families. Results: Of the 470 mismatch repair gene mutation carriers, 122 (26.0%) developed a colorectal adenoma during an overall median person time of 39.1 months. 40% of the study population used a dietary supplement. Use of any dietary supplement was not statistically significantly associated with colorectal adenoma risk (HR = 1.18; 95% CI 0.80-1.73). Multivitamin supplement use (HR = 1.15; 95% CI 0.72-1.84), vitamin C supplement use (HR = 1.57; 95% CI 0.93-2.63), calcium supplement use (HR = 0.69; 95% CI 0.25-1.92), and supplements containing fish oil (HR = 1.60; 95% CI 0.79-3.23) were also not associated with occurrence of colorectal adenomas. Conclusion: This prospective cohort study does not show inverse associations between dietary supplement use and occurrence of colorectal adenomas among individuals with Lynch syndrome. Further research is warranted to determine whether or not dietary supplement use is associated to colorectal adenoma and colorectal cancer risk in MMR gene mutation carriers.
Early life factors and adult mammographic density
Lokate, M. ; Duijnhoven, F.J.B. van; Berg, S.W. van den; Peeters, P.H. ; Gils, C.H. van - \ 2013
Cancer Causes and Control 24 (2013)10. - ISSN 0957-5243 - p. 1771 - 1778.
breast-cancer risk - reported birth-weight - perinatal characteristics - parenchymal patterns - women - metaanalysis - cohort - etiology - validity - stem
Purpose Early life factors have shown to be related to breast cancer risk. The pathophysiological link could be mammographic density, a strong risk factor for breast cancer. Mammary gland development already starts in utero and early life factors might affect the number of mammary cells at risk. In this study, we investigated the association between early life factors and mammographic density in adulthood. Methods The study was conducted within 2,588, mainly postmenopausal women of the Prospect-European Prospective Investigation into Cancer and Nutrition cohort. This ongoing study recruited breast cancer screening participants who filled out extensive questionnaires. Information on the early life factors birth weight, gestational age, maternal and paternal age, multiple births, birth rank, exposure to parental smoking, and leg length as a proxy for growth at childhood was obtained using questionnaires. Generalized linear models and linear regression models were used to study the relation between early life factors and mammographic density. Analyses were adjusted for potential confounders. Results Women who had an older mother (p = 0.06) or father (p = 0.002) at birth tended to have a higher mammographic density. Furthermore, greater leg length seemed to be related to higher mammographic density, although not statistically significantly (p = 0.16). After adjustment for confounders, none of the early life factors showed any statistically significant relationship with mammographic density in adulthood. Conclusion Although we cannot exclude small effects that go undetected due to measurement error in recall of early life factors, the results suggest that mammographic density is not a major pathway in any observed relationship between these early life events and breast cancer risk.
Allured or alarmed: Counteractive control responses to food temptations in the brain
Smeets, P.A.M. ; Kroese, F.M. ; Evers, C. ; Ridder, D.T.D. de - \ 2013
Behavioural Brain Research 248 (2013). - ISSN 0166-4328 - p. 41 - 45.
self-regulatory-success - menstrual-cycle phase - primary visual-cortex - attentional control - inhibitory control - goal activation - fmri - metaanalysis - reliability - validity
Typically, it is believed that palatable, high caloric foods signal reward and trigger indulgent responses. However, Counteractive Control Theory suggests that, to the extent that people are concerned about their weight, a confrontation with palatable foods should also trigger ‘alarm bell responses’ which promote successful self-control. Our study is the first to investigate such counteractive control processes in the brain employing functional magnetic resonance imaging (fMRI) in a sample of successful self-regulators. Indeed, besides the traditional finding that foods elicit heightened attention as witnessed by greater activation of primary visual cortex, we found that viewing palatable foods elicited brain activation in areas associated with self-regulation. Crucially, brain activation in self-regulation areas was related to diet importance. Thus, our results are the first to show that food cues not only evoke hedonic brain responses; in successful self-regulators they also trigger alarm bell responses, which may reflect the neural processes underlying successful self-control.
Adherence to the mediterranean diet and risk of breast cancer in the European prospective investigation into cancer and nutrition cohort study
Buckland, G. ; Travier, N. ; Cottet, V. ; Gonzalez, C.A. ; Lujan-Barroso, L. ; Agudo, A. ; Trichopoulou, A. ; Lagiou, P. ; Trichopoulos, D. ; Duijnhoven, F.J.B. van - \ 2013
International Journal of Cancer 132 (2013)12. - ISSN 0020-7136 - p. 2918 - 2927.
postmenopausal women - fatty-acid - patterns - estrogen - population - metaanalysis - calibration - rationale - validity - disease
Epidemiological evidence suggests that the Mediterranean diet (MD) could reduce the risk of breast cancer (BC). As evidence from the prospective studies remains scarce and conflicting, we investigated the association between adherence to the MD and risk of BC among 335,062 women recruited from 1992 to 2000, in ten European countries, and followed for 11 years on average. Adherence to the MD was estimated through an adapted relative Mediterranean diet (arMED) score excluding alcohol. Cox proportional hazards regression models were used while adjusting for BC risk factors. A total of 9,009 postmenopausal and 1,216 premenopausal first primary incident invasive BC were identified (5,862 estrogen or progesterone receptor positive [ER+/PR+] and 1,018 estrogen and progesterone receptor negative [ER-/PR-]). The arMED was inversely associated with the risk of BC overall and in postmenopausal women (high vs. low arMED score; hazard ratio [HR] = 0.94 [95% confidence interval [CI]: 0.88, 1.00] ptrend = 0.048, and HR = 0.93 [95% CI: 0.87, 0.99] ptrend = 0.037, respectively). The association was more pronounced in ER-/PR- tumors (HR = 0.80 [95% CI: 0.65, 0.99] ptrend = 0.043). The arMED score was not associated with BC in premenopausal women. Our findings show that adherence to a MD excluding alcohol was related to a modest reduced risk of BC in postmenopausal women, and this association was stronger in receptor-negative tumors. The results support the potential scope for BC prevention through dietary modification.
Physical activity and risk of breast cancer overall and by hormone receptor status: The European prospective investigation into cancer and nutrition
Steindorf, K. ; Ritte, R. ; Eomois, P.P. ; Lukanova, A. ; Tjonneland, A. ; Johnsen, N.F. ; Overvad, K. ; Ostergaard, J.N. ; Clavel-Chapelon, F. ; Duijnhoven, F.J.B. van - \ 2013
International Journal of Cancer 132 (2013)7. - ISSN 0020-7136 - p. 1667 - 1678.
postmenopausal women - estrogen-receptor - activity questionnaire - body-size - repeatability - validity - health - prevention - exercise - age
Physical activity is associated with reduced risks of invasive breast cancer. However, whether this holds true for breast cancer subtypes defined by the estrogen receptor (ER) and the progesterone receptor (PR) status is controversial. The study included 257,805 women from the multinational EPIC-cohort study with detailed information on occupational, recreational and household physical activity and important cofactors assessed at baseline. During 11.6 years of median follow-up, 8,034 incident invasive breast cancer cases were identified. Data on ER, PR and combined ER/PR expression were available for 6,007 (67.6%), 4,814 (54.2%) and 4,798 (53.9%) cases, respectively. Adjusted hazard ratios (HR) were estimated by proportional hazards models. Breast cancer risk was inversely associated with moderate and high levels of total physical activity (HR = 0.92, 95% confidence interval (CI): 0.86–0.99, HR = 0.87, 95%-CI: 0.79–0.97, respectively; p-trend = 0.002), compared to the lowest quartile. Among women diagnosed with breast cancer after age 50, the largest risk reduction was found with highest activity (HR = 0.86, 95%-CI: 0.77–0.97), whereas for cancers diagnosed before age 50 strongest associations were found for moderate total physical activity (HR = 0.78, 95%-CI: 0.64–0.94). Analyses by hormone receptor status suggested differential associations for total physical activity (p-heterogeneity = 0.04), with a somewhat stronger inverse relationship for ER+/PR+ breast tumors, primarily driven by PR+ tumors (p-heterogeneity <0.01). Household physical activity was inversely associated with ER–/PR– tumors. The results of this largest prospective study on the protective effects of physical activity indicate that moderate and high physical activity are associated with modest decreased breast cancer risk. Heterogeneities by receptor status indicate hormone-related mechanisms.
Mediterranean dietary pattern and prevalence and incidence of depressive symptoms in mid-aged women: results from a large community-based prospective study
Rienks, J. ; Dobson, A. ; Mishra, G.D. - \ 2013
European Journal of Clinical Nutrition 67 (2013). - ISSN 0954-3007 - p. 75 - 82.
mood disorders - short-form - fast-food - ces-d - association - cohort - health - risk - australia - validity
BACKGROUND/OBJECTIVES: To investigate the association between dietary patterns and prevalence and incidence 3 years later of depressive symptoms using data from the mid-aged cohort in the Australian Longitudinal Study on Women’s Health. SUBJECTS/METHODS: Participants (aged 50–55 years) completed a food frequency questionnaire in 2001. Depressive symptoms were measured in 2001 and 2004 using the validated 10-item Centre for Epidemiologic Studies Depression scale. Multiple logistic regression was used for cross-sectional analysis (8369 women) and longitudinal analysis (7588) to assess the associations between dietary patterns and prevalence of depressive symptoms, and then for longitudinal analysis (6060) on their associations with the incidence of depressive symptoms in 2004, while adjusting for sociodemographic and lifestyle factors. RESULTS: Six dietary patterns were identified from factor analysis: cooked vegetables, fruit, Mediterranean style, meat and processed meat, dairy, and high fat and sugar. A higher consumption of the Mediterranean-style diet had a cross-sectional association with lower prevalence of depressive symptoms in 2001, adjusted odds ratio 0.82 (95% confidence interval 0.77–0.88); and longitudinally with lower incidence of depressive symptoms in 2004, adjusted odds ratio 0.83 (0.75–0.91). None of the associations found for other dietary patterns remained statistically significant after adjustment for confounders. A dose–response relationship was found cross-sectionally when women were grouped according to quintiles of Mediterranean-style diet (P-value for trend o0.001). CONCLUSIONS: Consumption of a ‘Mediterranean-style’ dietary pattern by mid-aged women may have a protective influence against the onset of depressive symptoms. These findings suggest that dietary patterns have a potential role in the prevention and management of depressive symptoms.
Factor analysis is more appropriate to identify overall dietary patterns associated with diabetes when compared with treelet transform analysis
Schoenaker, D.A.J.M. ; Dobson, A. ; Soedamah-Muthu, S.S. ; Mishra, G.D. - \ 2013
The Journal of Nutrition 143 (2013)3. - ISSN 0022-3166 - p. 392 - 398.
adaptive multiscale basis - sparse unordered data - womens health - prevention - australia - validity - rotation - cohort - index
Treelet transform (TT) is a proposed alternative to factor analysis for deriving dietary patterns. Before applying this method to nutrition data, further analyses are required to assess its validity in nutritional epidemiology. We aimed to compare dietary patterns from factor analysis and TT and their associations with diabetes incidence. Complete data were available for 7349 women (50-55 y at baseline) from the Australian Longitudinal Study on Women's Health. Exploratory factor analysis and TT were performed to obtain patterns by using dietary data collected from an FFQ. Generalized estimating equations analyses were used to examine associations between dietary patterns and diabetes incidence. Two patterns were identified by both methods: a prudent and a Western dietary pattern. Factor analysis factors are a linear combination of all food items, whereas TT factors also include items with zero loading. The Western pattern identified by factor analysis showed a significant positive association with diabetes [highest quintile: OR = 1.94 (95% CI: 1.25, 3.00); P-trend = 0.001). Both factor analysis and TT involve different assumptions and subjective decisions. TT produces clearly interpretable factors accounting for almost as much variance as factors from factor analysis. However, TT patterns include food items with zero loading and therefore do not represent overall dietary patterns. The different dietary pattern loading structures identified by both methods result in different conclusions regarding the relationship with diabetes. Results from this study indicate that factor analysis might be a more appropriate method for identifying overall dietary patterns associated with diabetes compared with TT.
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