Nutrition Coordinating Center Research Articles

The Production of Quality Dietary Data: A Collaborative Effort of the Modification of Diet in Renal Disease Study

The production of research-quality dietary data for multicentered, long-duration, dietary intervention trials is complex and difficult. In the Modification of Diet in Renal Disease (MDRD) Study, quality control of dietary data has been accomplished through the cooperative efforts of MDRD clinical center dietitians, the MDRD Data Coordinating Center, and the MDRD Nutrition Coordinating Center. The rationale for and steps in the design of quality control protocols and the distribution of responsibilities among the MDRD collaborators are discussed. This model of shared responsibility may be a useful approach for future trials. The production of research-quality dietary data for multicentered, long-duration, dietary intervention trials is complex and difficult. In the Modification of Diet in Renal Disease (MDRD) Study, quality control of dietary data has been accomplished through the cooperative efforts of MDRD clinical center dietitians, the MDRD Data Coordinating Center, and the MDRD Nutrition Coordinating Center. The rationale for and steps in the design of quality control protocols and the distribution of responsibilities among the MDRD collaborators are discussed. This model of shared responsibility may be a useful approach for future trials.

A PROSPECTIVE POPULATION-BASED STUDY OF ALCOHOL USE AND NON-INSULIN-DEPENDENT DIABETES MELLITUS

The effect of alcohol use on risk of non-insulin-dependent diabetes mellitus was assessed in a defined population. A 24-hour recall of alcohol intake and past-week alcohol intake were obtained by separate interviewers between 1973 and 1975, and responses were coded by the Nutrition Coordinating Center, University of Minnesota. Of the 524 adults aged 30-79 years without diabetes at baseline, 31 men and 44 women were identified as diabetic by means of a glucose tolerance test (World Health Organization criteria) between 1984 and 1987. Men, but not women, who developed diabetes reported significantly more alcohol intake in the past week and in the past 24 hours. The highest rate of diabetes among alcohol users was in heavy drinkers--statistically significant only in men. Alcohol use remained a significant predictor of diabetes in men after adjustment for baseline age, body mass index (weight (kg)/height (m)2), cigarette smoking, family history of diabetes, and systolic blood pressure with a logistic regression model. The relative risk associated with past-week alcohol intake was 1.5 per 137.8 g; for past-24-hour alcohol intake, it was 1.5 per 24.5 g. Adjustment for baseline fasting plasma glucose and triglycerides did not change the results. Alcohol intake appears to be associated with risk of non-insulin-dependent diabetes mellitus in men.

Maintenance of a nutrient database for clinical trials

Maintenance of a nutrient database for use in dietary analysis for clinical trials and other medical research studies is described. The database, maintained at the University of Minnesota's Nutrition Coordinating Center (NCC), has been used to calculate dietary intake data for a wide range of diet-disease related investigations including studies on cardiovascular disease, hypertension, cancer, gastroenterology, and osteoporosis. Potential sources of error associated with nutrient databases are identified. Criteria are provided for the selection of a nutrient database to meet study objectives and to minimize the potential for errors and inconsistencies. NCC database maintenance procedures, designed to provide updated and verified nutrient calculations for clinical research, involve adherence to standardized procedures for all aspects of database maintenance including data selection, imputations, quality control, recipe calculations, and documentation. By maintaining multiple versions of the database, the NCC is able to update and expand a working version of the database while providing database stability for individual research studies.

Sources of data for developing and maintaining a nutrient database

A nutrient database that contains current, reliable data is a prerequisite for accurate calculation of dietary intakes. Most nutrient databases are expanded from data supplied by the U.S. Department of Agriculture and may include additional foods or nutrients or data from more recent analyses, food manufacturers, or foreign food tables. Guidelines must be established for selection of reliable values from appropriate sources. A system for precise documentation of data sources provides a means for determining whether individual nutrient values were derived from chemical analyses, recipe calculations, or imputations. This article identifies data sources used by the Nutrition Coordinating Center at the University of Minnesota for its nutrient database and describes the procedures used to select and document nutrient values. J Am Diet Assoc 88:1268, 1988.