Time of Dietary Energy and Nutrient Intake and Body Mass Index in Children: Compositional Data Analysis from the Childhood Obesity Project (CHOP) Trial.

Meal timing is suggested to influence the obesity risk in children. Our aim was to analyse the effect of energy and nutrient distributions at eating occasions (EO), including breakfast, lunch, supper, and snacks, on the BMI z-score (zBMI) during childhood in 729 healthy children. BMI and three-day dietary protocols were obtained at 3, 4, 5, 6, and 8 years of age, and dietary data were analysed as the percentage of the mean total energy intake (TEI; %E). Intakes at EOs were transformed via an isometric log-ratio transformation and added as exposure variables to linear mixed-effects models. Stratified analyses by country and recategorization of EOs by adding intake from snacks to respective meals for further analyses were performed. The exclusion of subjects with less than three observations and the exclusion of subjects who skipped one EO or consumed 5% energy or less at one EO were examined in sensitivity analyses. Around 23% of the children were overweight at a given time point. Overweight and normal-weight children showed different distributions of dietary intakes over the day; overweight children consumed higher intakes at lunch and lower intakes of snacks. However, no significant effects of timing of EOs on zBMI were found in regression analyses.

Evaluation of equipment performance, patient dose, imaging quality, and diagnostic coincidence in five Mexico City mammography services.

BACKGROUND: Regulations concerning the use of x-rays in medical diagnoses were published in Mexico in 1997. In this work, we evaluate technical aspects of mammography services in the Mexico City area and radiation dose and coincidence between the radiological interpretation by the institution radiologist and by a panel of experts. METHODS: Following methodology proposed by the American College of Radiology and the European Community among others, we have evaluated the performance of six mammography systems in Mexico City public and private services. The studied services carry out approximately one half of the mammography studies in the capital's metropolitan area. RESULTS: The systems comply with 53-82% of a total of 31 applied quality control tests and measurements, which include the mammography unit, x-ray generation, collimation, automatic exposure control, compression devices, grid and image receptor, film processing, darkroom, viewboxes, dose, film rejection, and image quality. The elements that most frequently fail are film processing, darkroom, and light boxes; average ACR phantom score is 11.2 (9.5, 12.0); mean average glandular dose measured with the phantom is 1.00 (0.71-1.15) mGy, and measured in patients is 1.75 (0.3, 4.9) mGy; coincidence between radiologic reports (BI-RADS) by the institution radiologist and a panel of experts is obtained in 35% of studied cases. CONCLUSIONS: Statistical analysis of results indicated that the level of equipment performance is correlated with image quality, image quality estimated by the panel of radiologists is correlated with phantom score, and coincidence in clinical mammography reports is not correlated with equipment performance and appears to depend on the radiologist's experience.