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N Slimani

Publications and source records attributed to N Slimani.

46 records · Page 3Linked to original sources
PubMed2000

Standardization of the 24-hour diet recall calibration method used in the european prospective investigation into cancer and nutrition (EPIC): general concepts and preliminary results.

OBJECTIVES: Despite increasing interest in the concept of calibration in dietary surveys, there is still little experience in the use and standardization of a common reference dietary method, especially in international studies. In this paper, we present the general theoretical framework and the approaches developed to standardize the computer-assisted 24 h diet recall method (EPIC-SOFT) used to collect about 37 000 24-h dietary recall measurements (24-HDR) from the 10 countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). In addition, an analysis of variance was performed to examine the level of standardization of EPIC-SOFT across the 90 interviewers involved in the study. METHODS: The analysis of variance used a random effects model in which mean energy intake per interviewer was used as the dependent variable, while age, body mass index (BMI), energy requirement, week day, season, special diet, special day, physical activity and the EPIC-SOFT version were used as independent variables. The analysis was performed separately for men and women. RESULTS: The results show no statistical difference between interviewers in all countries for men and five out of eight countries for women, after adjustment for physical activity and the EPIC-SOFT program version used, and the exclusion of one interviewer in Germany (for men), and one in Denmark (for women). These results showed an interviewer effect in certain countries and a significant difference between gender, suggesting an underlying respondent's effect due to the higher under-reporting among women that was consistently observed in EPIC. However, the actual difference between interviewer and country mean energy intakes is about 10%. Furthermore, no statistical differences in mean energy intakes were observed across centres from the same country, except in Italy and Germany for men, and France and Spain for women, where the populations were recruited from areas scattered throughout the countries. CONCLUSION: Despite these encouraging results and the efforts to standardize the 24-HDR interview method, conscious or unconscious behaviour of respondents and/or interviewer bias cannot be prevented entirely. Further evaluation of the reliability of EPIC-SOFT measurements will be conducted through validation against independent biological markers (nitrogen, potassium).

Analysis of Variance↗
PubMed1999

Structure of the standardized computerized 24-h diet recall interview used as reference method in the 22 centers participating in the EPIC project. European Prospective Investigation into Cancer and Nutrition.

A computerized 24-h diet recall interview program (EPIC-SOFT) was developed for use in a large European multi-center study, namely the European Prospective Investigation into Cancer and Nutrition (EPIC). This program, which was adapted for each participating country and translated into nine languages, was developed to standardize interviews between the 22 EPIC centers. Common rules were pre-entered into the system to describe, quantify and probe approximately 1500-2200 foods and 150-350 recipes. Common methods used to classify and export the EPIC-SOFT dietary data facilitate their exchange, comparison and analysis. So far, EPIC-SOFT is the only available computerized 24-h diet recall system developed to provide comparable food consumption data between several European countries.

Databases, Factual↗
PubMed1999

Comparison of nutrients in the food composition tables available in the nine European countries participating in EPIC. European Prospective Investigation into Cancer and Nutrition.

Food composition tables were studied from nine European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC): Denmark, France, Germany, Greece, Great Britain, Italy, The Netherlands, Spain and Sweden. They were compared from the point view of availability, definition, analytical methods, and mode of expression of the nutrients of interest for EPIC, and it was seen that most of the nutrients in the tables are analysed and expressed in a compatible way. For some nutrients, however, common methods and definitions (folate, dietary fibre), or modes of expression (energy, protein, carbohydrates, carotenes, vitamin A and E) have not yet been agreed upon, so values are not comparable. For vitamin C a wide range of values are found due to the high natural variation in foods. For compiled tables, an additional problem is the use of several sources which may mean that the nutritional values are not comparable within the same table; and these values cannot be converted if the source is not stated. In addition, some tables were compiled using food composition values produced over 20 years ago with outdated analytical methods. In view of the inconsistent values for some nutrients and due to the large amount of foods reported within EPIC, it was concluded that standardised food composition tables have to be developed for the nine European countries involved in EPIC in order to provide comparable nutrient intake data.

Databases, Factual↗
PubMed1998

[EPIC-SOFT a European computer program for 24-hour dietary protocols].

Within the EPIC study (European Prospective Investigation into Cancer and Nutrition) a calibration approach is applied to compare dietary data obtained by food frequency questionnaires from 9 European countries. A software for 24-h recalls was developed as the calibration instrument by the International Agency for Research on Cancer (IARC) in collaboration with all national EPIC centers. This computer program, called EPIC-SOFT, is an interview-based dietary assessment instrument that allows one to obtain a very detailed description and quantification of foods, recipes, and supplements consumed in the course of the preceding day. Probing questions and entering consumed foods in chronological order support the respondent's memory. The standardized structure prescribes--on the food group level--possibilities of description and quantification of food items to choose from. Quantification of consumed foods is supported by the EPIC-SOFT picture book that comprises colored photographs of foods in different portion sizes. The software provides an automatic coding of food items and recipe ingredients as well as calculation of nutrient intake. EPIC-SOFT is characterized by the obtained standardization of dietary data within Europe, a large number of available foods and recipes, and a very detailed description of consumed foods. Currently, EPIC-SOFT is one of the few dietary instruments providing comparable nutritional data within Europe.

Calibration↗
PubMed1997

Relative validity and reproducibility of a French dietary history questionnaire.

BACKGROUND: A self-administered dietary history questionnaire, especially developed for use in a large French prospective cohort study, was tested for accuracy of food intake measurement by comparing it to the average of 9-12 24-hour recalls. This questionnaire was structured according to the French meal pattern. An important feature of the questionnaire was the separation into a quantification part and qualification part. The first part quantifies consumption by frequency and portion sizes per food group or food item. The second part provides more detailed qualitative information on separate items within one food group. The total number of food items in the questionnaire was 238. METHODS: The questionnaire was administered twice to 119 study subjects, with an interval of approximately one year (1990-1991). During that year, 24-hour recalls were carried out monthly. Reproducibility and relative validity of the questionnaire were assessed. RESULTS: The correlation coefficients for reproducibility ranged from 0.40 to 0.74 for foods and from 0.54 to 0.75 for nutrients. The correlation coefficients for relative validity ranged from 0.10 to 0.71 for foods and from 0.29 to 0.81 for nutrients (adjustment for total energy and attenuation for nutrients). Percentage of subjects classified in the same or adjacent quintile by questionnaire as well as by 24-hour recall was on average 76% for foods and 72% for nutrients. CONCLUSIONS: These data indicate that this questionnaire can be used to classify study subjects according to their food or nutrient intake over a one-year period, within a known degree of precision.

Adult↗
PubMed1997

Estimation of reproducibility and relative validity of the questions included in the EPIC Physical Activity Questionnaire.

BACKGROUND: The EPIC core questionnaire on lifestyle contains a number of questions on physical activity designed to rank subjects according to level of physical activity (short PA questionnaire). These questions are based on a more extensive questionnaire designed to measure absolute total energy expenditure (extensive PA questionnaire), that was validated in a pilot study preceding EPIC. Reproducibility and relative validity of the short PA questionnaire were estimated by selecting, from the pilot study data, the answers to a number of questions from the extensive questionnaire that resembled those actually included in the short version. METHODS: The population of the pilot study consisted of 126 men and women aged between 20 and 70 years. Reproducibility was estimated by administering the extensive questionnaire three times: at baseline, and after 5 and 11 months. In order to determine the relative validity of the extensive questionnaire, a 3-day activity diary, repeated four times, was used as the reference method. RESULTS: Over the study period (13 months), mean absolute energy expenditure, estimated from the questions included in the short questionnaire, was fairly constant in men but not in women. REPRODUCIBILITY: Spearman correlation coefficients ranged from 0.47 to 0.89 in men, and from 0.49 to 0.81 in women. RELATIVE VALIDITY: Spearman correlation coefficients between the short questionnaire and the diary were between 0.32 and 0.81 for men, and between 0.28 and 0.72 for women. CONCLUSIONS: The questions selected for the short questionnaire are not suitable for estimating energy expenditure at an absolute level. Reproducibility and relative validity of the ranking of subjects seemed satisfactory and comparable to the extensive questionnaire. The results imply that the short questionnaire is suitable for ranking subjects in the EPIC study.

Adult↗
PubMed1997

Pilot phase studies on the accuracy of dietary intake measurements in the EPIC project: overall evaluation of results. European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: As part of the European Prospective investigation into Cancer and Nutrition (EPIC), preliminary studies were conducted to evaluate the accuracy of individuals' dietary intake measurements from newly developed questionnaires. METHODS: In six countries that adhered from the very beginning to the multicentre, co-ordinated EPIC project, the validity studies were based on two repeat questionnaire measurements at the start and at the end of a 1-year period, in groups of about 100 volunteers of both sexes. In addition, during this year, up to 12 24-hour recalls per person were taken monthly, and up to four blood and urine specimens were collected for measurement of biochemical markers. In three countries that joined EPIC later, the designs of the validity studies and type of 'reference' measurement chosen were somewhat different. The results presented in this overview paper are taken partly from more detailed, country-specific publications, and partly from a central (re-)analysis of the original data, to ensure a uniform approach to the statistical analyses and presentation. RESULTS: Averaged over subgroups by country and gender, Spearman coefficients of correlation between questionnaire measurements and the individuals' average 24-hour recalls ranged from 0.37 for fish to 0.68 for dairy products and 0.79 for alcoholic beverages. For energy-adjusted nutrient intakes (or nutrient densities, in the UK), mean Pearson correlation coefficients, corrected for residual attenuation due to day-to-day variations in the 24-hour recalls in all but two countries, ranged from 0.37 for retinol and 0.48 for vitamin E to 0.60 for carbohydrates and 0.12 for total alcohol intake. Correlations between energy-adjusted nutrient intakes and biochemical markers on average were low, but varied considerably between study centres. CONCLUSIONS: On average, most estimated correlation coefficient were of similar magnitude to those observed by independent research groups. The role of the preliminary validity studies, and various benefits drawn from these studies for further planning of the EPIC project are discussed.

Diet↗
PubMed1996

Identifiability of food components for cancer chemoprevention.

Epidemiological studies have consistently reported a reduction in risk for several cancer sites in relation to high consumption of vegetables and fruit. These findings stimulated further research aimed at identifying which compounds in fruit and vegetables are responsible for the reduction in cancer risk. Epidemiological and laboratory studies suggested that some micronutrients, particularly vitamin C, vitamin E, beta-carotene, selenium, magnesium and zinc, could reduce the risk of cancers of the oral cavity, lung, oesophagus and stomach, while dietary fibre was more specifically related to a reduced risk of colorectal cancer. However, the results of large randomized trials on various combinations of vitamins and minerals at supranutritional doses have so far failed to confirm this hypothesis or have found very weak effects. These results should stimulate profound re-thinking of the methods that led to the selection of specific molecules with potential chemopreventive action. From a methodological point of view, little attention has so far been given to four main limitations of nutritional epidemiology, which have direct bearing on the extrapolation of results from foods to food components. Measurements of micronutrient intakes through simple dietary questionnaires and current food composition tables lack precision and specificity. Micronutrient intakes are often highly correlated in nature because micronutrients tend to share the same food sources. Attribution of cancer risk to a single food constituent can be misleading if multicollinearity of dietary variables is not recognized. The etiological meaning of nutritional biomarkers is not straightforward because circulating levels of nutrients reflect not only dietary intake but also complex metabolic regulations. Studies have not considered the physical characteristics of foods, which are important determinants of physiological responses. Understanding the multidimensional nature of diet and of its relationship with different cancers is a major scientific challenge. Epidemiological studies combining detailed dietary questionnaires, appropriate food composition tables, multiple biomarkers, and appropriate statistical methods may provide better measurements of the relationships between cancer risk and specific dietary patterns and therefore contribute to the identification of food components with hitherto unforeseen potential interest for cancer prevention.

Anticarcinogenic Agents↗
PubMedDate not supplied

Relative validity and repeatability of a new questionnaire on physical activity.

BACKGROUND: A physical activity questionnaire was developed with the aim to estimate usual individual daily energy expenditure. The questionnaire focused on the number of hours usually spent on various activities. In a pilot study it was tested for repeatability and validity in a population of 126 Dutch adults (64 men, 62 women). METHODS: For assessment of repeatability the questionnaire was administered three times during the course of 1 year. A four-times-repeated 3-day activity diary was used as a reference instrument to evaluate validity. RESULTS: Differences in mean energy expenditure among repeated administrations of the questionnaire were small and not significant. Spearman's test-retest correlation coefficients for total energy expenditure for men were 0.76 [95% confidence interval (CI) 0.63-0.85] and 0.70 (95% CI 0.54-0.81) at 5 and 11 months, respectively, and for women were 0.58 (95% CI 0.36-0.74) and 0.71 (95% CI 0.54-0.82). There was a significant trend showing increasing mean diary energy expenditure for successive tertiles of questionnaire energy expenditure. The correlation between the questionnaire and the diary was 0.66 (95% CI 0.49-0.78) for men and 0.43 (95% CI 0.18-0.63) for women. CONCLUSIONS: It was concluded that this questionnaire is a useful tool for estimating energy expenditure in epidemiological studies.

Adult↗