Catherine S. Berkey

Activity, Dietary Intake, and Weight Changes in a Longitudinal Study of Preadolescent and Adolescent Boys and Girls

Objective. To examine the role of physical activity, inactivity, and dietary patterns on annual weight changes among preadolescents and adolescents, taking growth and development into account. Study Design. We studied a cohort of 6149 girls and 4620 boys from all over the United States who were 9 to 14 years old in 1996. All returned questionnaires in the fall of 1996 and a year later in 1997. Each child provided his or her current height and weight and a detailed assessment of typical past-year dietary intakes, physical activities, and recreational inactivities (TV, videos/VCR, and video/computer games). Methods. Our hypotheses were that physical activity and dietary fiber intake are negatively correlated with annual changes in adiposity and that recreational inactivity (TV/videos/games), caloric intake, and dietary fat intake are positively correlated with annual changes in adiposity. Separately for boys and girls, we performed regression analysis of 1-year change in body mass index (BMI; kg/m2). All hypothesized factors were in the model simultaneously with several adjustment factors. Results. Larger increases in BMI from 1996 to 1997 were among girls who reported higher caloric intakes (.0061 ± .0026 kg/m2 per 100 kcal/day; β ± standard error), less physical activity (−.0284 ± .0142 kg/m2/hour/day) and more time with TV/videos/games (.0372 ± .0106 kg/m2/hour/day) during the year between the 2 BMI assessments. Larger BMI increases were among boys who reported more time with TV/videos/games (.0384 ± .0101) during the year. For both boys and girls, a larger rise in caloric intake from 1996 to 1997 predicted larger BMI increases (girls: .0059 ± .0027 kg/m2 per increase of 100 kcal/day; boys: .0082 ± .0030). No significant associations were noted for energy-adjusted dietary fat or fiber. Conclusions. For both boys and girls, a 1-year increase in BMI was larger in those who reported more time with TV/videos/games during the year between the 2 BMI measurements, and in those who reported that their caloric intakes increased more from 1 year to the next. Larger year-to-year increases in BMI were also seen among girls who reported higher caloric intakes and less physical activity during the year between the 2 BMI measurements. Although the magnitudes of these estimated effects were small, their cumulative effects, year after year during adolescence, would produce substantial gains in body weight. Strategies to prevent excessive caloric intakes, to decrease time with TV/videos/games, and to increase physical activity would be promising as a means to prevent obesity.

Reproducibility and Validity of Maternal Recall of Pregnancy-related Events

We assessed the reproducibility and validity of a questionnaire that asks mothers to recall pregnancy-related events from thirty or more years ago. Among 146 women who completed the questionnaire twice, responses were highly reproducible for pre-pregnancy height and weight (r = 0.95), pregnancy complications (r = 0.74), substance use (r = 0.80), preterm delivery (r = 0.82), birthweight (r = 0.94), and breastfeeding (r = 0.89). Among 154 women whose questionnaire responses were compared to data collected during their pregnancies, recall was highly accurate for height (r = 0.90), pre-pregnancy weight (r = 0.86), birthweight (r = 0.91), and smoking (sensitivity = 0.86, specificity = 0.94). These findings suggest that long-term maternal recall is both reproducible and accurate for many factors related to pregnancy and delivery.

Longitudinal study of skipping breakfast and weight change in adolescents

BACKGROUND: Several cross-sectional studies reported that heavier children eat breakfast less often. However, no longitudinal studies have addressed whether skipping breakfast leads to excessive weight gain.OBJECTIVE: To investigate whether skipping breakfast was prospectively associated with changes in body fatness.METHODS: A cohort of >14 000 boys and girls from all over the US, 9- to 14-y-old in 1996, returned annual mailed questionnaires (1996–1999) for the Growing Up Today Study. We analyzed change in body mass index (BMI; kg/m2) over three 1-y periods among children who reported breakfast frequency.RESULTS: Children who reported that they never eat breakfast had lower energy intakes than those who eat breakfast nearly every day. Children who were more physically active reported higher energy intakes, as did those who reported more time watching television/videos and playing videogames. Like previous studies, skipping breakfast was associated with overweight, cross-sectionally. However, overweight children who never ate breakfast lost BMI over the following year compared to overweight children who ate breakfast nearly every day (boys: −0.66 kg/m2 (s.e.=0.22); girls: −0.50 kg/m2 (s.e.=0.14)). But normal weight children who never ate breakfast gained weight relative to peers who ate breakfast nearly every day (boys: +0.21 kg/m2 (s.e.=0.13); girls: +0.08 kg/m2 (s.e.=0.05)). Breakfast frequency was positively correlated with self-reported quality of schoolwork.CONCLUSIONS: Overweight children who never eat breakfast may lose body fat, but normal weight children do not. Since numerous studies link skipping breakfast to poorer academics, children should be encouraged to eat breakfast.

Overweight, weight concerns, and bulimic behaviors among girls and boys.

OBJECTIVE To assess the prevalence rates and correlates of overweight, concern with weight, and bulimic behaviors. METHOD A survey was completed by a population-based sample of 16,114 boys and girls aged 9 to 14 years. RESULTS Although fewer girls (19%) than boys (26%) were overweight, more girls (25% versus 22%) perceived themselves as overweight (p < .001). The proportion of girls reporting trying to lose weight increased with age (p < .001). The prevalence of binge eating at least monthly increased with age among the girls, but remained stable among the boys. The prevalence of purging was low (< or = 1%) and comparable between genders until age 13. Among the 13- and 14-year-olds, girls were significantly more likely than boys to report using laxatives or vomiting to control weight (p < or = .001). Purging was independently positively associated with stage of pubertal development (girls: odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.6-2.7; boys: OR = 1.5, 95% CI 1.0-2.2) and overweight (girls: OR = 1.9, 95% CI 1.2-3.0; boys: OR = 2.7, 95% CI 1.4-5.1). CONCLUSIONS Misperception of being overweight and concern with weight were common. Purging was a very rare behavior, but increased with pubertal development. Among the girls, the prevalence increased sharply around the onset of adolescence.

Association of Consumption of Fried Food Away From Home With Body Mass Index and Diet Quality in Older Children and Adolescents

Objectives. Rates of overweight have increased dramatically among children in the United States. Although an increase in consumption of food prepared away from home has paralleled overweight trends, few data exist relating food prepared away from home to change in BMI in children. The goals of this study were to (1) examine the cross-sectional and longitudinal associations between consumption of fried foods away from home (FFA) and BMI and (2) examine the cross-sectional associations between intake of FFA and several measures of diet quality. Methods. We studied a cohort of 7745 girls and 6610 boys, aged 9 to 14 years, at baseline in 1996. We obtained BMI from self-reported height and weight, measures of diet quality from a food frequency questionnaire, and weekly servings of FFA during the previous year. We performed linear regression analyses to assess the longitudinal associations between change in consumption of FFA on change in BMI, using data from three 1-year periods from 1996 through 1999. We also related consumption of FFA with intake of selected foods and nutrients at baseline. Results. In cross-sectional analyses, adjusting for potential confounders, mean (SE) BMI was 19.1 (0.13) among children who ate FFA “never or <1/week,” 19.2 (0.13) among those who responded “1 to 3 times/week,” and 19.3 (0.18) among those who responded “4 to 7 times/week.” In longitudinal multivariate models, increasing (over 1 year) consumption of FFA “never or <1/week” to “4 to 7/week” was associated with increasing BMI (β = 0.21 kg/m2; 95% confidence interval: 0.03–0.39) compared with those with low consumption of FFA at baseline and 1 year later. At baseline, frequency of eating FFA was associated with greater intakes of total energy, sugar-sweetened beverages, and trans fat, as well as lower consumption of low-fat dairy foods and fruits and vegetables. Conclusions. These data suggest that older children who consume greater quantities of FFA are heavier, have greater total energy intakes, and have poorer diet quality. Furthermore, increasing consumption of FFA over time may lead to excess weight gain.

Functional electrostimulation in poststroke rehabilitation: a meta-analysis of the randomized controlled trials.

OBJECTIVE To assess the efficacy of functional electrical stimulation (FES) in the rehabilitation of hemiparesis in stroke. DESIGN A meta-analysis combined the reported randomized controlled trials of FES in stroke, using the effect size method of Glass, and the DerSimonian-Laird Random Effects Method for pooling studies. SETTING The included studies were published between 1978 and 1992. They were conducted in academic rehabilitation medicine settings. PATIENTS In all included studies, patients were in poststroke rehabilitation. The mean time after stroke varied from 1.5 to 29.2 months. INTERVENTION FES applied to a muscle or associated nerve in a hemiparetic extremity was compared to No FES. MAIN OUTCOME MEASURE Change in paretic muscle force of contraction following FES was compared to change without FES. RESULTS For the four included studies, the mean effect size was .63 (95% CI: .29, .98). This result was statistically significant (p < .05). CONCLUSION Pooling from randomized trials supports FES as promoting recovery of muscle strength after stroke. This effect is statistically significant. There is a reasonable likelihood of clinical significance as well.

Dietary essential fatty acids, long-chain polyunsaturated fatty acids, and visual resolution acuity in healthy fullterm infants: a systematic review

BACKGROUND Biologically active neural tissue is rich in docosahexaenoic acid (DHA), an omega-3 long-chain polyunsaturated fatty acid (LCPUFA). We conducted a systematic review to examine the nature of discordant results from studies designed to test the hypothesis that dietary DHA leads to better performance on visually-based tasks in healthy, fullterm infants. We also conducted a meta-analysis to derive combined estimates of behavioral- and electrophysiologic-based visual resolution acuity differences and sample sizes that would be useful in planning future research. STUDY DESIGN AND METHODS Twelve empirical studies on LCPUFA intake during infancy and visual resolution acuity were identified through bibliographic searches, examination of monograph and review article reference lists, and written requests to researchers in the field. Works were reviewed for quality and completeness of information. Study design and conduct information was extracted with a standardized protocol. Acuity differences between groups consuming a source of DHA and groups consuming DHA-free diets were calculated as a common outcome from individual studies; this difference score was evaluated against a null value of zero and then used, with the method of DerSimonian and Laird (Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-188), to derive combined estimates of visual resolution acuity differences within seven age categories. RESULTS OF RANDOMIZED COMPARISONS: The combined visual resolution acuity difference measured with behaviorally based methods between DHA-supplemented formula fed groups and DHA-free formula fed groups is 0.32+/-0.09 octaves (combined difference+/-S.E.M., P=0.0003) at 2 months of age. The direction of this value indicates higher acuity in DHA-fed groups. RESULTS OF NON-RANDOMIZED STUDY DESIGNS: The combined visual resolution acuity difference measured with behaviorally based methods between human milk fed groups and DHA-free formula fed groups is 0.49+/-0.09 octaves (P< or =0.000001) at 2 months of age and 0.18+/-0.08 octaves (P=0.04) at 4 months of age. Acuity differences for electrophysiologic-based measures are also greater than zero at 4 months (0.37+/-0.16 octaves, P=0.02). CONCLUSION Some aspect of dietary n-3 intake is associated with performance on visual resolution acuity tasks at 2, and possibly, 4 months of age in healthy fullterm infants. Whether n-3 intake confers lasting advantage in the development of visually based processes is still in question.

Efficacy and safety of nonsteroidal antiinflammatory drugs for cancer pain: a meta-analysis.

PURPOSE To assess the efficacy and safety of nonsteroidal antiinflammatory drugs (NSAIDs) in the treatment of cancer pain by meta-analyses of the published randomized control trials (RCTs). PATIENTS AND METHODS Twenty-five studies met inclusion criteria for analysis. Of these, 13 tested a single-dose effect, nine multiple-dose effects, and three both single- and multiple-dose effects of 16 different NSAIDs in a total of 1,545 patients. Baseline pain intensity (when provided) of moderate or higher was indicated in 81% of patients. RESULTS Single-dose NSAID studies found greater analgesic efficacy than placebo, with rough equivalence to 5 to 10 mg of intramuscular morphine. Pain scores differed insignificantly for aspirin versus three other NSAIDs. Analgesic responses to low- and high-dose NSAIDs suggested a dose-response relationship, but this was not statistically significant. Recommended and supramaximal single doses of three NSAIDs produced comparable changes in pain scores, which indicates a ceiling analgesic effect. Common side effects included upper gastrointestinal symptoms, dizziness, and drowsiness. The incidence of side effects showed a trend to increase with dose, without a ceiling effect, and to increase with multiple doses. Single or multiple doses of weak opioids (WO) alone or in combination (WO/C) with nonopioid analgesics did not produce greater analgesia than NSAIDs alone. Single doses of WO/C analgesics produced more side effects than NSAIDs alone, although both side effect incidence and patient dropout rates were equal when multiple doses were administered. CONCLUSION These findings question whether the traditional World Health Organization (WHO) second analgesic step (addition of a weak opioid when pain is inadequately treated by a nonopioid analgesic alone) is warranted. A lack of comparable studies precluded testing the hypothesis that NSAIDs are particularly effective for malignant bone pain.

Adolescence and breast carcinoma risk

Breast carcinoma risk may be modified by early life factors, including physical growth and development, diet, and life‐style factors of preadolescence and adolescence, as well as genetic factors.

Meta-analysis of multiple outcomes by regression with random effects

Earlier work showed how to perform fixed-effects meta-analysis of studies or trials when each provides results on more than one outcome per patient and these multiple outcomes are correlated. That fixed-effects generalized-least-squares approach analyzes the multiple outcomes jointly within a single model, and it can include covariates, such as duration of therapy or quality of trial, that may explain observed heterogeneity of results among the trials. Sometimes the covariates explain all the heterogeneity, and the fixed-effects regression model is appropriate. However, unexplained heterogeneity may often remain, even after taking into account known or suspected covariates. Because fixed-effects models do not make allowance for this remaining unexplained heterogeneity, the potential exists for bias in estimated coefficients, standard errors and p-values. We propose two random-effects approaches for the regression meta-analysis of multiple correlated outcomes. We compare their use with fixed-effects models and with separate-outcomes models in a meta-analysis of periodontal clinical trials. A simulation study shows the advantages of the random-effects approach. These methods also facilitate meta-analysis of trials that compare more than two treatments.