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Biomedical subjects

Linda S Adair

Publications and source records attributed to Linda S Adair.

At least 19 recordsLinked to original sources
PubMed2006

Quantifying the urban environment: a scale measure of urbanicity outperforms the urban-rural dichotomy.

The rapid urbanization of the developing world has important consequences for human health. Although several authorities have called for better research on the relationships between urbanicity and health, most researchers still use a poor measurement of urbanicity, the urban-rural dichotomy. Our goal was to construct a scale of urbanicity using community level data from the Cebu Longitudinal Health and Nutrition Survey. We used established scale development methods to validate the new measure and tested its performance against the dichotomy. The new scale illustrated misclassification by the urban-rural dichotomy, and was able to detect differences in urbanicity, both between communities and across time, that were not apparent before. Furthermore, using a continuous measure of urbanicity allowed for better illustrations of the relationships between urbanicity and health. The new scale is a better measure of urbanicity than the traditionally used urban-rural dichotomy.

Environment↗
PubMed2006

The relationship between pregnancy weight gain and glucose tolerance status among black and white women in central North Carolina.

OBJECTIVE: The objective of the study was to examine weight and its relationship to glucose intolerance during pregnancy. STUDY DESIGN: Women were classified into mutually exclusive glucose tolerance groups; impaired glucose tolerance of pregnancy defined as 1 high value on the oral glucose tolerance test, gestational diabetes mellitus as 2 high values, and normal glucose tolerance as a normal value on the universal screen test. Logistic regression was used to examine the relationship between prepregnancy body mass index and weight gain, and glucose tolerance status and predicted probabilities were calculated. RESULTS: Weight gain ratio (observed/expected) was significantly higher for women with gestational diabetes mellitus, compared with women with normal glucose tolerance. The likelihood of developing gestational diabetes mellitus was significantly increased by both prepregnancy overweight (odds ratio 2.2, 95% confidence interval 1.1-4.3) and obese status (odds ratio 3.7, 95% confidence interval 2.2-6.3) but only marginally by weight gain ratio. In contrast, the likelihood of developing impaired glucose tolerance was increased by weight gain ratio for women who started pregnancy overweight. CONCLUSION: Prepregnancy weight was strongly associated with gestational diabetes mellitus, whereas weight gain during pregnancy was associated with impaired glucose tolerance only among overweight women.

Adult↗
PubMed2006

Body mass index gain, fast food, and physical activity: effects of shared environments over time.

OBJECTIVE: The magnitude of environmental vs. genetic effects on BMI, diet, and physical activity (PA) is widely debated. We followed a sibling cohort (where individuals shared households in childhood and adolescence) to young adulthood (when some continued sharing households and others lived apart) to examine the role of discordant environments in adult twins' divergent trends in BMI and health behaviors and to quantify the variation in BMI and behavior among all siblings that is attributable to environmental and additive genetic effects. RESEARCH METHODS AND PROCEDURES: In the National Longitudinal Study of Adolescent Health, siblings sharing households for > or =10 years as adolescents (mean age = 16.5 +/- 1.7 years; N = 5524) were followed into adulthood (mean = 22.4 +/- 1.8 years; N = 4368), self-reporting PA, sedentary behavior, and dietary characteristics. Adult BMI and adolescent z scores were derived from measured height and weight. RESULTS: Compared with those living together, twins living apart exhibited greater discordance in change in BMI, PA, and fast food intake from adolescence to adulthood. Adolescent household environments accounted for 8% to 10% of variation in adolescent fast food intake and sedentary behaviors and 50% of variation in adolescent overweight. Adolescent household effects on PA were substantially greater in young adulthood (accounting for 50% of variation) vs. adolescence. Young adult fast food intake was significantly affected by young adult household environment, accounting for 12% of variation. DISCUSSION: These findings highlight important environmental influences on BMI, PA, and fast food intake during the transition to adulthood. Household and physical environments play an important role in establishing long-term behavior patterns.

Adolescent↗
PubMed2005

Adolescent physical activity and sedentary behavior: patterning and long-term maintenance.

BACKGROUND: Little is known about physical activity (PA) and sedentary behavior patterning or its impact on long-term PA sustainability, particularly during the critical transition from adolescence to adulthood. METHODS: Nationally representative self-reported data were collected (National Longitudinal Study of Adolescent Health: Wave I, 1994-1995; Wave II, 1996; Wave III, 2001-2002). Cluster analyses identified homogeneous groups of adolescents with similar PA and sedentary behaviors. Logistic regression predicted odds of meeting national activity recommendations in adolescence and young adulthood. RESULTS: Seven clusters were characterized as follows: C1, high television (TV)/video, video gaming; C2, high skating, video gaming; C3, high sports participation with parents, high overall sports participation; C4, use of neighborhood recreation centers, high sports participation; C5, TV viewing limited by parents, moderate participation in school physical education (PE); C6, low parental TV control, reporting few activities overall; C7, active in school (team/individual sports, academic clubs, and PE). Odds of adolescents meeting PA recommendations were highest in C2 (odds ratio=13.1), C3 (5.8), C4 (4.2), and C7 (4.3) compared to C1. Independent of adolescent PA, absolute odds of meeting recommendations as young adults declined but were still relatively high in these clusters, indicating greater long-term PA sustainability. By young adulthood, however, overall PA declined dramatically in skaters/gamers (C2) and was notably low among those with TV viewing limited by parents (C5). CONCLUSIONS: While odds of meeting PA guidelines in adulthood declined in all clusters, the magnitude of this decline varied by cluster (declining most dramatically in skaters/gamers), providing insights into where to target effective intervention strategies that promote sustainable PA behaviors.

Adolescent↗
PubMed2005

Are child eating patterns being transformed globally?

OBJECTIVE: To examine the extent to which child dietary patterns and trends are changing globally. RESEARCH METHODS AND PROCEDURES: Diets of children 2 to 19 years of age were studied with nationally representative data from Russia and the United States, nationwide data from China, and regional data from metropolitan Cebu, Philippines. Twenty-four-hour dietary recalls were examined at several points in time to examine trends in calories consumed away from home, snacking behavior, and soft drink and modern fast food consumption. Urban-rural trends were compared. RESULTS: U.S. and Cebu youth consume more than one-third of their daily calories and a higher proportion of snack calories from foods prepared away from home. In contrast, away from home food consumption is minimal in Chinese and Russian children. U.S. and Cebu youth consume about one-fifth of their total daily energy from snacks, but snacks provide a much lower proportion of energy in Russia ( approximately 16%) and China (where snacks provide only approximately 1% of energy). Fast food plays a much more dominant role in the American diet ( approximately 20% of energy vs. 2% to 7% in the other countries), but as yet does not contribute substantially to children's diets in the other countries. Urban-rural differences were found to be important, but narrowing over time, for China and Cebu, whereas they are widening for Russia. DISCUSSION: This research suggests that globalization of the fast food and other modern food sectors is beginning to affect child eating patterns in several countries undergoing nutrition transition. However, the contribution of fast food and soft drinks to the diet of children remains relatively small in China, Russia, and Cebu, Philippines, relative to the United States.

Adolescent↗
PubMed2005

Breast-feeding influences cognitive development in Filipino children.

The importance of breast-feeding (BF) for cognitive development has been researched widely over the past several decades. Although scholars agree that children who breast-feed are generally more intelligent, it is uncertain whether this advantage is due to BF effects or to other accompanying healthy characteristics of women who breast-feed. This is a problem in nearly every study, and even in studies controlling for known confounding variables, residual confounding remains a concern. This study tried a new approach, evaluating the relation between BF and cognitive development or ability in a population in which BF was inversely correlated with socioeconomic advantages and other healthy maternal behaviors. Normal birthweight (NBW, n = 1790) and low birthweight (LBW, n = 189) (<2500 g) infants born in 1983-84 in Metropolitan Cebu, Philippines were followed from birth through middle childhood. Cognitive ability was assessed at ages 8.5 and 11.5 y with the Philippines Nonverbal Intelligence Test. Multivariable linear regressions were created to estimate crude and adjusted relations of various BF measures and later cognitive ability. After controlling for confounding variables, scores at 8.5 y were higher for infants breast-fed longer (1.6 points and 9.8 points higher among NBW and LBW infants, respectively, breast-fed for 12 to <18 mo vs. <6 mo). BF coefficients in both NBW and LBW 11.5-y models were attenuated but remained positive. This analysis highlights the importance of long-term BF after initial introduction of complementary foods, particularly in LBW infants born close to term.

Birth Weight↗
PubMed2005

The association between diet and height in the postinfancy period changes with age and socioeconomic status in Filipino youths.

Whether the determinants of linear growth can have independent effects beyond the critical infancy period has been questioned. This research uses uniquely suited data from >2000 youths from the Cebu Longitudinal Health and Nutrition Study in the Philippines to examine the association between diet and height in the postinfancy period. Anthropometric, diet, and other data were collected bimonthly from 0 to 2 y, and at the mean ages of 8, 11.5, 15.5, and 18.5 y. Generalized Estimating Equations were used to quantify the mean effects of diet diversity and energy intake on height across increments demarcated by the postinfancy data (2-8.5, 8.5-11.5, 11.5-15.5, and 15.5-18.5 y). We examined whether the effects differed by socioeconomic status (SES) and age. Effects with P < 0.05 were considered significant. Each additional unit of diet variety (range 0-8 U) was associated with a significant 0.33-cm increase in height in boys. Each additional 100 kcal (4186 kJ) was associated with significant increases in height of 0.05 cm in boys, and 0.02 cm in girls. Significant interactions (P < 0.15) with SES showed that each 100 kcal increase in energy intake was associated with a 0.08-cm increase in height at low SES with no difference at high SES. In both boys and girls, the effects of energy intake decreased with age, as shown by a significant age interaction (P < 0.15). The methods used incorporate the longitudinal nature of the data to offer a unique examination of the association between diet and height in the postinfancy period.

Adolescent↗
PubMed2005

Are adolescents who were breast-fed less likely to be overweight? Analyses of sibling pairs to reduce confounding.

BACKGROUND: Cohort analyses suggesting that breast-feeding protects against being overweight have been criticized for inadequately controlling for confounding associated with the self-selection of feeding practices. METHODS: Using nationally representative U.S. data from the National Longitudinal Study of Adolescent Health (1994-1996), we performed traditional cohort analyses (n = 11,998) using logistic regression to estimate the relation between breast-feeding and adolescent overweight (body mass index > or =85 percentile, based on year 2000 CDC growth charts), controlling for known potential confounders. Breast-feeding also was assessed in a subsample of 850 sibling pairs to account for unmeasured genetic and environmental factors. RESULTS: Among girls in the full cohort, the odds of being overweight declined among those who had been breast-fed at least 9 months; odds ratios ranged from 0.90 (95% confidence interval = 0.74-1.09) for <3 months of breast-feeding to 0.78 (0.64-0.96) for > or =9 months. A similar effect was seen in boys, although these trends were less consistent. In contrast, an analysis of sibling pairs provided no evidence of breast-feeding effects on weight within discordant trends. CONCLUSION: Cohort data indicate that odds of being overweight decrease as breast-feeding duration increases, at least among girls. However, sibling analyses suggest that this relationship may not be causal but rather attributable to unmeasured confounding related to mothers' choice to breast-feed, or to other childhood risk factors for overweight. Our results illustrate the utility of sibling analyses in understanding the true effect of early life exposures (such as breast-feeding) on health outcomes over time, independent of confounding factors that may not be satisfactorily controlled using traditional prospective cohort methods.

Adolescent↗
PubMed2004

Understanding the role of mediating risk factors and proxy effects in the association between socio-economic status and untreated hypertension.

The association between socio-economic status (SES) and untreated hypertension varies according to a country's level of development and racial/ethnic group. We sought to confirm this variation in women from China and the United States (US) as well as to investigate the impact of SES on several mediating risk factors. We also investigate the extent to which SES explains racial/ethnic differences in untreated hypertension in the US. We used cross-sectional data from 1814 non-pregnant women in China (China Health and Nutrition Survey (CHNS), 1997) and 3266 non-pregnant women in the United States (National Health and Nutrition Examination Survey (NHANES III), 1988-1994) respectively. A variety of statistical modelling techniques was used to predict untreated hypertension as a function of several mediating factors and to simulate the impact of changes in SES. The age-adjusted prevalence of untreated hypertension was significantly higher (p<0.01) for low-income White and Black women compared to Mexican American or Chinese women. Untreated hypertension was not significantly associated with income or education in Mexican Americans or women in China. Obesity and light physical activity had the largest mediating effect on the association between SES and untreated hypertension for all racial/ethnic groups. However, this effect was not as strong as the proxy effect of income and education. SES did not completely explain racial/ethnic differences in hypertension in the US. While SES was more strongly associated with hypertension in Blacks than Whites, Blacks were still 1.97 (95% CI 1.47-2.64) times more likely to have untreated hypertension than Whites after adjusting for SES differences. The association between SES and untreated hypertension varied by country and racial/ethnic group. An important explanation for this variation was the differential effect of SES on mediating risk factors. SES disparities between Whites and Blacks in the US partly explain differences in the prevalence of untreated hypertension between these racial/ethnic groups.

Adult↗
PubMed2004

Dramatic rise in overweight and obesity in adult filipino women and risk of hypertension.

OBJECTIVE: To assess trends in BMI of adult Filipino women over a 16-year period of rapid socioeconomic change; to identify factors associated with those trends; and to estimate the risk of hypertension associated with overweight, obesity, and high waist-to-hip ratio (WHR). RESEARCH METHODS AND PROCEDURES: Women from randomly selected urban and rural communities of Metro Cebu, Philippines were recruited during a 1983 to 1984 index pregnancy, then followed prospectively for 16 years. Overweight and obesity were defined using BMI cut-off points of 25 and 30, respectively. The analysis sample included women 15 to 45 years of age when measured 4 months postpartum. Weight change in subsequent intervals from 1985 to 1999 was modeled using linear regression. The relationship of BMI and WHR to risk of hypertension in the last survey was modeled using logistic regression. RESULTS: The prevalence of overweight and obesity combined increased nearly 6-fold from approximately 6% in 1983 to 1984 to 35% in 1998 to 1999. Weight gain was positively associated with urban residence, improved socioeconomic status, fewer pregnancies and months of lactation, and more away-from-home work hours. Risk of hypertension was independently elevated by high WHR and overweight/obesity. DISCUSSION: The dramatic trend of increasing overweight and obesity in this sample of women represents a serious health concern, especially in light of the strong association of excess weight, particularly in the truncal region, to risk of hypertension.

Adolescent↗
PubMed2004

Macronutrient and selected vitamin intakes from complementary foods of infants and toddlers from Cebu, Philippines.

Intakes of macronutrients (energy, protein, fat, and carbohydrate) and vitamins (vitamin A, thiamin, riboflavin, niacin, and vitamin C) (per day and per 100 kcal) from complementary foods by a cohort of Filipino breast-fed infants and toddlers (n=1794) were studied at 10, 16, and 22 months of age using a single 24-h recall. With the exception of protein, intakes of energy and vitamins for all age groups were below the World Health Organization estimated needs and desired nutrient densities from complementary foods regardless of breast-feeding frequency. Nutrient deficits were greater for rural children compared with urban children, and were attributed to low intakes of energy, as well as cellular animal protein, fruits and vegetables.

Breast Feeding↗
PubMed2004

Effect of macronutrient intake on the development of glucose intolerance during pregnancy.

BACKGROUND: Dietary intake influences glucose tolerance status, yet the relation between macronutrient intake and the development of glucose intolerance during pregnancy has not been adequately examined. OBJECTIVE: We examined the relation between macronutrient intake early in pregnancy and the development of glucose intolerance. DESIGN: Data are from 1698 women in the Pregnancy, Infection, and Nutrition Study. Dietary intake during the second trimester was assessed with a food-frequency questionnaire. Women were classified into 1 of 3 glucose categories: gestational diabetes mellitus (GDM), impaired glucose tolerance (IGT), and normal glucose tolerance. Multivariate logistic regression was used to calculate the relative risk of IGT and GDM, with adjustment for potential confounders. A series of models were specified to test alternate hypotheses about the relation of diet to risk of IGT or GDM. RESULTS: The overall prevalences of IGT and GDM in the cohort were 2.6% and 5.2%, respectively. The addition model showed that adding 100 kcal from carbohydrates to the diet was associated with a 12% decrease in risk of IGT and a 9% decrease in risk of GDM. The substitution model showed that substituting fat for carbohydrates (per each 1% of total calories) resulted in a significant increase in risk of both IGT and GDM [relative risk = 1.1 (95% CI: 1.02, 1.12) and 1.1 (1.02, 1.10), respectively]. Predicted probabilities of IGT and GDM were reduced by one-half with a 10% decrease in dietary fat and a 10% increase in carbohydrate. CONCLUSIONS: This study found an association between increased fat intake and the development of glucose abnormalities in pregnancy.

Adult↗
PubMed2004

Five-year obesity incidence in the transition period between adolescence and adulthood: the National Longitudinal Study of Adolescent Health.

BACKGROUND: No nationally representative longitudinal data have been analyzed to evaluate the incidence of obesity in the transition between adolescence and adulthood. OBJECTIVE: The objective was to examine dynamic patterns of change in obesity among white, black, Hispanic, and Asian US teens as they transitioned to young adulthood. DESIGN: We used nationally representative, longitudinally measured height and weight data collected from US adolescents enrolled in wave II (1996; ages 13-20 y) and wave III (2001; 19-26 y) of the National Longitudinal Study of Adolescent Health (n = 9795). Obesity incidence was defined on the basis of International Obesity Task Force (IOTF) cutoffs (wave II), which link childhood body mass index (BMI) centiles to adult cutoffs (BMI > or = 30; wave III), for comparability between adolescence and adulthood. In addition, the more commonly used cutoff of BMI > or = 95th percentile for age- and sex-specific cutoffs from the 2000 Centers for Disease Control and Prevention growth charts for adolescents (wave II) were compared with adult cutoffs (BMI > or = 30; wave III). RESULTS: On the basis of the IOTF cutoffs, obesity incidence over the 5-y study period was 12.7%; 9.4% of the population remained obese and 1.6% shifted from obese to nonobese. Obesity incidence was especially high in non-Hispanic black (18.4%) females relative to white females. The prevalence of obesity increased from 10.9% in wave II to 22.1% in wave III, and extreme obesity was 4.3% at wave III on the basis of a BMI > or = 40. CONCLUSIONS: During a 5-y transitional period between adolescence and young adulthood, the proportion of adolescents becoming and remaining obese into adulthood was very high. This upward trend is likely to continue. Effective preventive and treatment efforts are critically needed.

Adolescent↗
PubMed2004

Growth in young Filipino children predicts schooling trajectories through high school.

Several studies link childhood malnutrition to adverse schooling outcomes, including delayed or diminished enrollment and increased grade repetition. However, the effects of nutrition on schooling trajectories are obscured by the cross-sectional nature of most previous research and the complex array of other phenomena that affect schooling outcomes. We explored the association between height-for-age Z-score (HAZ) at 2 y and schooling trajectory among 2198 children from the Cebu Longitudinal Health and Nutrition Survey. Parity, parental education, maternal height, household assets, environmental cleanliness, presence of electricity, and household income were identified as potential confounders. Crude and adjusted logistic and multinomial regressions of schooling outcomes (entrance age, grade repetition, and grades completed) were conducted. Entrance age and IQ were evaluated as potential mediators between HAZ and schooling outcomes. After adjustment for confounders, greater height for age protected against late enrollment among both boys and girls and predicted early enrollment among boys. Taller children were less likely to repeat grades [girls OR = 0.78 (0.67, 0.89); boys OR = 0.86 (0.74, 0.99)] and less likely to drop out during grade school rather than graduate from high school [girls OR = 0.74 (0.56, 0.98; boys OR = 0.66 (0.51, 0.84)]. Models predicting the changes in school outcomes associated with a change in overall height from -2 to 0 SD of HAZ were simulated. Absolute probability of late enrollment dropped substantially, from 6% for both boys and girls to 2% for boys and 1% for girls. Absolute grade repetition dropped approximately 7% for boys and 9% for girls. Improving early childhood nutrition may have long-lasting educational benefits, increasing the likelihood of high school completion in developing countries.

Aging↗
PubMed2003

Rapid child growth raises blood pressure in adolescent boys who were thin at birth.

Catch-up growth in previously growth-restricted children is a suggested risk factor for chronic disease risk. We use data from 2026 Filipino adolescents to identify periods of growth that matter more for risk of high blood pressure (BP). Subjects were drawn from the Cebu Longitudinal Health and Nutrition Survey, which enrolled pregnant women and followed up their offspring through age 14 to 16 years. High BP was defined as the top 10% of residuals from gender-specific regressions of systolic and diastolic BP on age and height. After controlling for birth length, current body mass index, age, and height, the odds of high BP in males were significantly decreased with each kilogram increase in birth weight. The highest odds of elevated BP occurred among males who were relatively thin at birth but relatively heavy as adolescents. Larger weight increments from birth to 2 years decreased the odds of high BP in boys, whereas larger increments from 8 to 11 and 11 to 16 years increased the odds of high BP. Thinness at birth significantly interacted with growth rate after age 8, such that a high rate of weight gain increased risk only among boys who were in the lower two thirds of the body mass index distribution at birth. Results in girls indicated small or no effects of early growth. The synergistic effect on adolescent BP of rapid weight gain from late childhood into adolescence with thinness at birth is further evidence of fetal programming of BP in males and suggests long-term health risks associated with rapid growth, even in the absence of obesity.

Adolescent↗
PubMed2003

The relationship of ethnicity, socioeconomic factors, and overweight in US adolescents.

OBJECTIVE: To examine the extent to which race/ethnic differences in income and education account for sex-specific disparities in overweight prevalence in white, African American, Hispanic, and Asian U.S. teens. RESEARCH METHODS AND PROCEDURES: We used nationally representative data collected from 13113 U.S. adolescents enrolled in the National Longitudinal Study of Adolescent Health. Logistic regression models were used to examine the relationship of family income and parental education to overweight prevalence (body mass index >or= 85th percentile of age and sex-specific cutoff points from the 2000 Centers for Disease Control and Prevention/National Center for Health Statistics growth charts). In addition, we used coefficients from our logistic regression models to project the effects on overweight prevalence of equalizing the socioeconomic status (SES) differences between race/ethnic groups. RESULTS: Keeping adolescents in their same environments and changing only family income and parental education had a limited effect on the disparities in overweight prevalence. Ethnicity-SES-overweight differences were greater among females than males. Given that overweight prevalence decreased with increasing SES among white females and remained elevated and even increased among higher SES African-American females, African-American/white disparity in overweight prevalence increased at the highest SES. Conversely, disparity was lessened at the highest SES for white, Hispanic, and Asian females. Among males, disparity was lowest at the average SES level. DISCUSSION: One cannot automatically assume that the benefits of increased SES found among white adults will transfer to other gender-age-ethnic groups. Our findings suggest that efforts to reduce overweight disparities between ethnic groups must look beyond income and education and focus on other factors, such as environmental, contextual, biological, and sociocultural factors.

Adolescent↗
PubMed2003

Estimating body fat from anthropometry and isotopic dilution: a four-country comparison.

OBJECTIVE: The goal was to assess the ability of BMI to predict body fat (BF) among youths in four countries and identify the degree to which additional anthropometric measures improve this prediction. BMI is widely recommended as an indicator of overweight. However, whether BMI adequately estimates BF and has the same meaning in different ethnic groups and youths has been questioned. RESEARCH METHODS AND PROCEDURES: Data come from 456 Filipino, Chinese, Russian, and black South African youths, 6 to 16 years old. Percentage BF and fat mass index (FMI) were estimated by the deuterium dilution method. Skinfold thicknesses (triceps, subscapular, and suprailiac) and weight and height measures were collected. Percentage BF was regressed first on BMI and age and then with the addition of the skinfold measures. Linear models were run separately by country and sex. The models were repeated with FMI as the outcome. RESULTS: The R2 values from the percentage BF models ranged from 0.13 to 0.69 in the first models to 0.38 to 0.81 in the full models. The values were lowest among Russian males > or = 13 years and Russian females > or = 13 years of age in the reduced and full models, respectively, and were highest among Chinese females. Using FMI as the outcome did not meaningfully change the results. DISCUSSION: The ability of BMI to adequately predict BF and the additional predictivity of anthropometric measures varied widely across the samples, making its uniform use as a proxy for BF in youths from different countries questionable.

Adipose Tissue↗