David E. Chiriboga

Seasonal variation in food intake, physical activity, and body weight in a predominantly overweight population

Objective:To describe seasonal variation in food intake, physical activity, and body weight in a predominantly overweight population.Design:A longitudinal observational study.Setting:Most of the study participants were recruited from a health maintenance organization (HMO) in central Massachusetts, USA. Additional individuals of Hispanic descent were recruited from outside of the HMO population to increase the ethnic diversity of this sample.Subjects:Data from 593 participants, aged 20–70, were used for this investigation. Each participant was followed quarterly (five sampling points: baseline and four consecutive quarters) for 1-year period. Body weight measurements and three 24-h dietary and physical activity recalls were obtained on randomly selected days (including 2 weekdays and 1 weekend day) per quarter. Sinusoidal regression models were used to estimate peak-to-trough amplitude and phase of the peaks.Results:Daily caloric intake was higher by 86 kcal/day during the fall compared to the spring. Percentage of calories from carbohydrate, fat and saturated fat showed slight seasonal variation, with a peak in the spring for carbohydrate and in the fall for total fat and saturated fat intake. The lowest physical activity level was observed in the winter and the highest in the spring. Body weight varied by about 1/2 kg throughout the year, with a peak in the winter (P<0.001 winter versus summer). Greater seasonal variation was observed in subjects who were male, middle aged, nonwhite, and less educated.Conclusions:Although there is seasonal variation in diet, physical activity and body weight, the magnitude of the change is generally small in this population.Sponsorship:US National Heart, Lung and Blood Institute.

Association between carbohydrate intake and serum lipids

Background: The effect of dietary carbohydrate on blood lipids has received considerable attention in light of the current trend in lowering carbohydrate intake for weight loss. Objectives: To evaluate the association between carbohydrate intake and serum lipids. Methods: Blood samples and 24-hour dietary and physical activity recall interviews were obtained from each subject at quarterly intervals for five consecutive quarters between 1994 and 1998 from 574 healthy adults in Central Massachusetts. Relationships between serum lipids and dietary carbohydrate factors were assessed using linear mixed models and adjusting for other risk factors known to be related to blood lipids. Both cross-sectional and longitudinal results were reported. Results: Cross-sectional analysis results from this study suggest that higher total carbohydrate intake, percentage of calories from carbohydrate, glycemic index (GI) and/or glycemic load (GL) are related to lower high-density lipoprotein cholesterol (HDL-C) and higher serum triacylglycerol levels, while higher total carbohydrate intake and/or GL are related to lower total and low-density lipoprotein cholesterol (LDL-C) levels. In a one-year longitudinal analysis, GL was positively associated with total and LDL-C levels, and there was an inverse association between percentage of calories from carbohydrate and HDL-C levels. Conclusions: Results suggest that there is a complex and predominantly unfavorable effect of increased intake of highly processed carbohydrate on lipid profile, which may have implications for metabolic syndrome, diabetes, and coronary heart disease. Further studies in the form of randomized controlled trials are required to investigate these associations and determine the implications for lipid management.

A comparison of selected nutrient intakes derived from three diet assessment methods used in a low-fat maintenance trial.

OBJECTIVE In the vast majority of surveys and research in humans, dietary data are obtained from self-reports: recalls; records; or historical methods, usually food frequency questionnaires (FFQ). This study provides a rare opportunity to compare data derived from all three methods. DESIGN A crossover study of dietary fat in which data were collected using an average of 11.4 food records and 11.7 24-h diet recalls. Using simple subtraction and correlation, energy and nutrient intakes derived from the three methods were compared to each other and with those derived from a single FFQ. Analysis of variance was used to evaluate sources of variability in nutrient intakes estimated from the individual days of records and recalls. SETTING An independent, free-standing medical research institute. SUBJECTS 13 men who were compliant with study procedures. RESULTS FFQ-derived estimates of energy and nutrient intake were highest (e.g. 1967 kcal versus 1858 kcal and 1936 kcal for the records and recalls, respectively). Mean differences in energy and nutrient intakes and their variances were lowest and correlation coefficients highest in comparing the records and recalls (e.g. for fat the mean difference was 5.0 g, and r = 0.85). Analysis of variance of individual days of record- and recall-derived data (n = 300) revealed that there was no effect due to either method (record or recall) or the sequence of administration. CONCLUSIONS Results of this study indicate that the FFQ overestimated dietary intake. Energy and nutrient results obtained from the records and recalls were interchangeable. However, based on smaller SDs around the means, it appears that the recalls may perform slightly better in estimating dietary intake in groups such as these well-educated, highly compliant men.

Gender Differences in Predictors of Body Weight and Body Weight Change in Healthy Adults

Background: Overweight and obesity are important predictors of a wide variety of health problems. Analysis of naturally occurring changes in body weight can provide valuable insights in improving our understanding of the influence of demographic, lifestyle, and psychosocial factors on weight gain in middle‐age adults.

Temporal trends (1975 through 1990) in the incidence and case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction. A communitywide perspective.

BACKGROUND As part of a population-based study of acute myocardial infarction, we examined changes over time in the incidence and in-hospital case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction. METHODS AND RESULTS Patients with validated acute myocardial infarction hospitalized at 16 hospitals in the Worcester, Mass, metropolitan area between 1975 and 1990 comprised the study sample. During the 15-year study period, 5.1% of patients developed primary ventricular fibrillation in the setting of uncomplicated acute myocardial infarction, with this rate remaining relatively constant over time. Both age- and multivariable-adjusted analyses showed no significant trend in the incidence rates of primary ventricular fibrillation during the study period. The in-hospital case-fatality rate for patients with primary ventricular fibrillation was significantly elevated compared with the rate for those without primary ventricular fibrillation and uncomplicated acute myocardial infarction (48.3% versus 1.5%, P < .001). No significant change over time was noted in in-hospital case-fatality rates associated with primary ventricular fibrillation while controlling for a variety of short-term prognostic factors. CONCLUSIONS The results of this communitywide observational study suggest that neither the incidence nor the prognosis associated with primary ventricular fibrillation resulting from acute myocardial infarction has improved over time.

Association between dietary glycemic index, glycemic load, and high-sensitivity C-reactive protein

OBJECTIVE This study examined the relation between quality of dietary carbohydrate intake, as measured by glycemic index (GI) and glycemic load (GL), and serum high-sensitivity C-reactive protein (hs-CRP) levels. METHODS During a 1-y observational study, data were collected at baseline and at each quarter thereafter. GI and GL were calculated from multiple 24-h dietary recalls (24HRs), 3 randomly selected 24HRs at every quarter, with up to 15 24HRs per participant. The hs-CRP was measured in blood samples collected at baseline and each of the four quarterly measurement points. Multivariable linear mixed models were used to examine the cross-sectional and longitudinal associations of GI, GL, and hs-CRP. RESULTS Among 582 adult men and women with at least two measurements of diet and hs-CRP, average daily GI score (white bread = 100) was 85 and average GL was 198, and average hs-CRP was 1.84 mg/L. Overall, there was no association between GI or GL and hs-CRP. Subgroup analyses revealed an inverse association between GL and hs-CRP among obese individuals (body mass index > or =30 kg/m(2)). CONCLUSION Quality of dietary carbohydrates does not appear to be associated with serum hs-CRP levels. Among obese individuals, higher dietary GL appears to be related to lower hs-CRP levels. Due to the limited number of studies on this topic and their conflicting results, further investigation is warranted.

PDA-assisted low glycemic index dietary intervention for type II diabetes: a pilot study

Background:Epidemiological and dietary intervention studies suggest that a low-glycemic index (GI) diet is beneficial for blood glucose control; however, long-term clinical utility of the low GI diet has not been fully investigated.Objectives:To evaluate the feasibility and efficacy of a nutritionist-delivered low-GI dietary intervention, with the support of a personal digital assistant (PDA), for adult patients with poorly controlled type II diabetes.Method:The low-GI intervention consisted of six counseling sessions and the use of a PDA-based food database with GI scores for 6 months. Study outcomes included feasibility measures, glycosylated hemoglobin levels (HbA1c), GI and glycemic load (GL) score of self-reported dietary intake, body weight, depression and quality of life (QOL). Measures were obtained at baseline, 3 and 6 months.Results:Of 31 adult patients approached, 15 met study eligibility criteria and were enrolled in the study. Thirteen patients (87%) completed all study assessments. Findings included decreases in average HbA1c (−0.5% P=0.02), body weight, hip circumference, blood pressure, dietary GI and daily caloric intake. Diabetes impact scores also decreased. All but one participant completed all components of the intervention. There were mixed reports regarding the usefulness of the PDAs; however, participants offered helpful suggestions for further development.Conclusions:Results of this pilot study support the feasibility of implementing a nutritionist-delivered, PDA-assisted low-GI dietary intervention for patients with poorly controlled type II diabetes. Encouraging initial efficacy data require further testing in the context of a randomized clinical trial.

Association between Depression and C-Reactive Protein

Objective. Depression has been associated with increased cardiovascular disease risk, and a depression-related elevation of high sensitivity C-reactive protein (hs-CRP) has been proposed as a possible mechanism. The objective of this paper is to examine association between depression and high sensitivity C-reactive protein (hs-CRP). Methods. Subjects consisted of 508 healthy adults (mean age 48.5 years; 49% women, 88% white) residing in central Massachusetts. Data were collected at baseline and at quarterly intervals over a one-year period per individual. Multivariable linear mixed models were used to assess the association for the entire sample and by gender. Results. The mean Beck Depression Inventory score was 5.8 (standard deviation (SD) 5.4; median 4.3), and average serum hs-CRP was 1.8 mg/L (SD 1.7; median 1.2). Results from the multivariable linear mixed models show that individuals with higher depression scores have higher levels of hs-CRP. Analyses by gender show persistence of an independent association among women, but not among men. Body mass index (BMI = weight(kg)/height(m)2) appears to be a partial mediator of this relationship. Conclusion. Depression score was correlated to hs-CRP levels in women. Further studies are required to elucidate the biological mechanisms underlying these associations and their implications.

Contemporary Trends in Evidence-based Treatment for Acute Myocardial Infarction

BACKGROUND Guidelines for the management of patients with acute myocardial infarction recommend the routine use of 4 effective cardiac medications: angiotensin-converting enzyme inhibitors, aspirin, beta-blockers, and lipid-lowering agents. Limited data are available, however, about the contemporary and changing use of these therapies, particularly from a population-based perspective. The study describes differences in the use of these medications during hospitalization for acute myocardial infarction according to age, gender, and period of hospitalization. METHODS The study population consisted of 6334 women and men treated at 11 hospitals in the Worcester, Mass, metropolitan area for acute myocardial infarction in 6 annual periods between 1995 and 2005. RESULTS Increases in the use of all 4 cardiac medications during hospitalization for acute myocardial infarction were noted between 1995 and 2005 for all men and in those of different age strata: less than 65 years (4%-47%); 65 to 74 years (4%-46%); 75 to 84 years (2%-48%); and more than 85 years (0%-23%). Increases in the use of all 4 cardiac medications also were observed in all women and in those of all ages over time (2%-42%); 65 to 74 years (8%-47%); 75 to 84 years (1%-44%); and more than 85 years (1%-44%). CONCLUSION The present results suggest marked increases over time in the use of evidence-based therapies in patients hospitalized with acute myocardial infarction. Educational efforts to augment the use of these effective cardiac therapies, as well as attempts to identify suboptimally treated groups, remain warranted.

Seasonal and Sex Variation of High-Sensitivity C-Reactive Protein in Healthy Adults: A Longitudinal Study

BACKGROUND Cross-sectional studies have reported seasonal variation in high-sensitivity C-reactive protein (hsCRP). However, longitudinal data are lacking. METHODS We collected data on diet, physical activity, psychosocial factors, physiology, and anthropometric measurements from 534 healthy adults (mean age 48 years, 48.5% women, 87% white) at quarterly intervals over a 1-year period between 1994 and 1998. Using sinusoidal regression models, we estimated peak-to-trough amplitude and phase of the peaks. RESULTS At baseline, average hsCRP was 1.72 mg/L (men, 1.75 mg/L; women, 1.68 mg/L). Overall seasonal variation amplitude was 0.16 mg/L (95% CI 0.02 to 0.30) and was lower in men (0.10 mg/L, 95% CI -0.11 to 0.31) than in women (0.23 mg/L, 95% CI 0.04 to 0.42). In both sexes, hsCRP peaked in November, with a corresponding trough in May. Relative plasma volume, waist and hip circumference, diastolic blood pressure, and depression scores were major factors associated with changes in amplitude of seasonal variation of hsCRP, and taken together explain most of the observed seasonal change. There was a 20% increase in the percentage of participants classified in the high-risk category for hsCRP (> or =3 mg/L) during late fall and early winter compared with late spring and early summer. CONCLUSIONS Concentrations of hsCRP were modestly increased in fall and winter compared to summer, with greater seasonal amplitude of variation observed in women. Conventional classification methods fail to consider seasonality in hsCRP and may result in substantial misclassifications in the spring and fall. Future clinical practice and research should take these variations into account.