Reliability of anthropometric measures in a longitudinal cohort of patients initiating ART in West Africa.

BACKGROUND: Anthropometric measurements are a non invasive, inexpensive, and suitable method for evaluating the nutritional status in population studies with relatively large sample sizes. However, anthropometric techniques are prone to errors that could arise, for example, from the inadequate training of personnel. Despite these concerns, anthropometrical measurement error is seldom assessed in cohort studies. We describe the reliability and challenges associated with measurement of longitudinal anthropometric data in a cohort of West African HIV+ adults . METHODS: In a cohort of patients initiating antiretroviral treatment in Mali, we evaluated nutritional status using anthropometric measurements(weight, height, mid-upper arm circumference, waist circumference and triceps skinfold). Observers with no prior experience in the field of anthropometry were trained to perform anthropometrical measurements. To assess the intra- and inter-observer variability of the measurements taken in the course of the study, two sub-studies were carried out: one at the beginning and one at the end of the prospective study. Twelve patients were measured twice on two consecutive days by the same observer on both study occasions. The technical error of measurement (TEM) (absolute and relative value), and the coefficient of reliability (R) were calculated and compared across reliability studies. RESULTS: According to the R and relative TEM, inter-observer reliabilities were only acceptable for height and weight. In terms of intra-observer precision, while the first and second anthropometrists demonstrated better reliability than the third, only height and weight measurements were reliable. Looking at total TEM, we observed that while measurements remained stable between studies for height and weight, circumferences and skinfolds lost precision from one occasion to the next. CONCLUSIONS: Height and weight were the most reliable measurements under the study's conditions. Circumferences and skinfolds demonstrated less reliability and lost precision over time, probably as a result of insufficient supervision over the entire length of the study. Our results underline the importance of a careful observer's selection, good initial preparation, as well as the necessity of ongoing training and supervision over the entire course of a longitudinal nutritional study. Failure to do so could have major repercussions on data reliability and jeopardize its utilization.

Psychosocial correlates of body mass index in four groups of Quebec adults.

The objective of the present analysis was to study the associations between body weight psychosocial correlates and body mass index (BMI) among four groups of adults in the Quebec population. Data were taken from the Social Lifestyles and Health 1998 Survey performed by the Institut de la Statistique du Québec (ISQ). The suggested guidelines of the ISQ were used to estimate the population's proportions and for statistical analysis. The groups studied were 25- to 44- and the 45- to 64-year-old men and women. In all groups, currently trying to lose weight increased the odds of reporting an excess weight. Better perceived eating habits was associated with lower BMI in most groups except in the 25- to 44-year-old women, where the trend was not significant. Higher number of physical activities related to transport and cigarette smoking were associated with lower BMI in both men groups. In both women groups, more frequent consumption of alcoholic beverages decreased significantly the odds of reporting excess body weight. A university degree was associated with a lower BMI only in the 25- to 44-year-old men. Regular practise of leisure time physical activity was associated with a lower BMI only in 45- to 64-year-old women. Opposite associations were observed between perceived health and BMI. In the 45- to 64-year-old men, better perceived health increased the odds of reporting an excess weight. Conversely, the odds of reporting excess weight decreased with better health in 25- to 44-year-old women. Many correlates differ between age group and sex. The identification of these factors illustrates the need to adapt obesity-related programmes toward specific sub-groups within the general population.

Correlates of diet quality in the Quebec population.

OBJECTIVE: To determine the correlates of a high-fat diet in urban, suburban and rural areas of Quebec, Canada. DESIGN: A secondary analysis of data collected as part of a 5-year multi-factorial, multi-setting, community-intervention project. SETTING: Urban, suburban and rural settings of the province of Quebec, 1997. SUBJECTS: Data were analysed from a sample of 5214 participants (2227 males, 2987 females). A food-frequency questionnaire was completed and a global index of food quality was calculated. Logistic regression was used to identify correlates of a diet high in total fats, saturated fat and cholesterol. RESULTS: In both genders, lower level of education, smoking status, French and English languages compared with other languages spoken at home, and a rural environment were associated with poor diet quality. Having no intention to eat low-fat dairy products more often was associated with a high-fat diet. In men, obesity (body mass index >/=30 kg m(-2)) and absence of reported health problems were correlates of a high-fat diet, while, in women, lower physical activity was a correlate. CONCLUSIONS: Future health interventions in Quebec should target people with low education, smokers and those living in a rural environment. Obese men and sedentary women should have access to specific dietetic resources.

Effects of the Quebec Heart Health Demonstration Project on adult dietary behaviours.

BACKGROUND: There are few studies which have evaluated the dietary impact of multiple community-based cardiovascular disease prevention programs. METHODS: A 5-year, multifactorial community-based heart disease prevention program was conducted by regional public health departments in three sites: urban, suburban and rural. The experimental and control communities were composed of independent samples of 4,863 adults in 1993 and 5,260 in 1997. The impact of the program on diet was assessed by a validated, self-administered food frequency questionnaire which yielded a Global Dietary Index (GDI). RESULTS: The urban and suburban sites showed improvements in mean GDI in both exposed and non-exposed groups while the rural site mean GDI showed deterioration in both groups (n.s.). The analysis of variance showed that the group x year interaction terms were not significant for each site and sex, indicating that the intervention did not have measurable effects on dietary behaviours. Inclusion of confounding variables did not alter those findings. Analyses of specific food group indices gave similar results. CONCLUSIONS: Future intervention programs could benefit from considering physical and social environments as well as public policy changes to improve efficacy.

The Québec Child and Adolescent Health and Social Survey: design and methods of a cardiovascular risk factor survey for youth.

BACKGROUND: Although atherosclerosis begins in childhood, there are no recent Canadian data on cardiovascular risk factors in provincially or nationally representative samples of youth. OBJECTIVE: To describe the design and methods of the 1999 Québec Child and Adolescent Health and Social Survey, which assessed the prevalence and distribution of risk factors in a representative sample of Québec youth. METHODS: School-based, multistage, cluster sampling survey of youth aged nine, 13 and 16 years. Measures included height, weight, subscapular and tricipital skinfolds, blood pressure (measured with the Dinamap), a fasting blood draw for assessment of lipoproteins and glucose, an age-adapted youth questionnaire on lifestyles and a parent questionnaire. RESULTS: One thousand two hundred sixty-seven, 1186 and 1160 subjects aged nine, 13 and 16 years, respectively, responded to the questionnaire and had height, weight, skinfold thickness and blood pressure measured (response proportions of 83%, 79% and 78% respectively); 783, 818 and 874 subjects of the same age agreed to the blood draw (response proportions of 52%, 55% and 59%, respectively). Comparisons of characteristics of participants and nonparticipants in the blood draw showed few differences. The mean relative difference between lipoprotein and glucose values obtained at the study laboratory and a reference method varied from -0.3% to 6.1%. Design effects for means and proportions varied from 1.0 to 1.8. CONCLUSION: Despite its complexity, this survey was able to achieve a high level of precision for multiple measures. It will provide the most complete data on cardiovascular risk factors ever collected among children and adolescents in Canada.

Membrane peroxidation by lipopolysaccharide and iron-ascorbate adversely affects Caco-2 cell function: beneficial role of butyric acid.

BACKGROUND: Membrane lipid peroxidation may play a role in immune-mediated bowel diseases. OBJECTIVE: We examined the effects of lipopolysaccharide (LPS), a ubiquitous endotoxin mediator of gram-negative bacteria, alone and in combination with iron-ascorbate, on enterocyte function. Furthermore, we assessed the antioxidant capacity of butylated hydroxytoluene (BHT) and butyric acid, which are known to play a significant role in the welfare of intestinal mucosa. DESIGN: Differentiated intestinal Caco-2 cells were used to study the induction of membrane peroxidation by LPS (100 micro g/mL) and iron-ascorbate (0.2 and 2 mmol/L, respectively) and to examine the beneficial effects of BHT and butyric acid. RESULTS: A significant dose-dependent increase in malondialdehyde, accompanied by lower apical membrane fluidity and significantly decreased sucrase activity, was observed when Caco-2 cells were incubated with LPS. LPS also augmented paracellular permeability ([(14)C]polyethylene glycol flux), prostaglandin E(2) production, and cyclooxygenase-2 (EC 1.14.99.1) expression. These abnormalities were exacerbated by the coadministration of iron-ascorbate, but most of them were suppressed by butyric acid and BHT. CONCLUSION: Bacterial endotoxin and prooxidants may overwhelm antioxidant defenses and become deleterious to enterocyte function, whereas butyric acid and BHT may provide antioxidant protection.

The antioxidant BHT normalizes some oxidative effects of iron + ascorbate on lipid metabolism in Caco-2 cells.

We showed recently that iron + ascorbate can impair the assembly of intestinal lipoproteins. However, we could not determine whether these changes were caused by iron + ascorbate-mediated lipid peroxidation per se. We therefore conducted studies to evaluate how antioxidants antagonize the iron + ascorbate-induced derangements. To this end, Caco-2 cells, a reliable experimental intestinal model, were incubated with iron + ascorbate (0.2 mmol/L each) alone or with different concentrations of catalase, mannitol, tocopherol or BHT. Exposing Caco-2 cells to iron + ascorbate increased malondialdehyde levels fourfold (P < 0.0001); this effect was decreased markedly (P < 0.02) in the presence of BHT. Furthermore, BHT normalized the abnormal intracellular events involved in fat absorption, i.e., lipid esterification, cholesterol synthesis and apolipoprotein production. On the other hand, it did not fully restore the secretion of lipids and lipoproteins. Thus, our current data imply that iron + ascorbate-catalyzed lipid peroxidation is partially responsible for the disturbances observed in intestinal lipid transport.