REPRODUCIBILITY OF A COMPREHENSIVE DIET HISTORY IN THE DIABETES CONTROL AND COMPLICATIONS TRIAL

Objective To evaluate the reproducibility of a modified Burke-type die t history within the context of a long-term, randomized, 29-center cli nical diabetes study. Design Diet histories were collected by trained interviewers at the end of years 1 and 2 after subjects were randomly assigned to the intensive treatment group or the conventional treatmen t group. Mean daily intakes of energy, protein, carbohydrate, total fa t, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, cholesterol, and dietary fiber were calculated for each treatment group at each time period. Subjects The study population con sisted of 139 subjects in the intensive treatment group and 128 subjec ts in the conventional treatment group. Ages ranged from 13 to 39 year s; groups included men and women. Distribution by age, sex, race, prop ortion of smokers, weight reported as percent ideal body weight, and d uration of IDDm were similar in both groups. Statistical methods Diffe rences in nutrient intake between the conventional and intensive treat ment groups at each time period were tested for significance using the Wilcoxon rank-sum test. The Wilcoxon paired differences test was used to assess changes between time periods within treatment groups. Linea r agreement between repeated administrations of the diet history was e valuated using Pearson's correlation coefficient, and the extent of wi thin-subject reproducibility was assessed by intraclass correlation. R esults No statistically significant differences in energy and nutrient intakes were observed between the two groups at either year 1 or year 2. Within each treatment group, energy and nutrient intake difference s between times were not statistically significant. Correlation coeffi cients between years 1 and 2 ranged from .51 for dietary fiber to .72 for dietary cholesterol; within-subject reproducibility was slightly h igher. Applications These results demonstrate long-term reproducibilit y for the meal-based diet history in the DCCT population.