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Biomedical subjects

Dimitri A Christakis

Publications and source records attributed to Dimitri A Christakis.

At least 19 recordsLinked to original sources
PubMed2007

Dietary energy density is associated with obesity and the metabolic syndrome in U.S. adults.

OBJECTIVE: Rising obesity rates have been linked to the consumption of energy-dense diets. We examined whether dietary energy density was associated with obesity and related disorders including insulin resistance and the metabolic syndrome. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional study using nationally representative data of U.S. adults > or =20 years of age from the 1999-2002 National Health and Nutrition Examination Survey (n = 9,688). Dietary energy density was calculated based on foods only. We used a series of multivariate linear regression models to determine the independent association between dietary energy density, obesity measures (BMI [in kilograms per meters squared] and waist circumference [in centimeters]), glycemia, or insulinemia. We used multivariate Poisson regression models to determine the independent association between dietary energy density and the metabolic syndrome as defined by the National Cholesterol and Education Program (Adult Treatment Panel III). RESULTS: Dietary energy density was independently and significantly associated with higher BMI in women (beta = 0.44 [95% CI 0.14-0.73]) and trended toward a significant association in men (beta = 0.37 [-0.007 to 0.74], P = 0.054). Dietary energy density was associated with higher waist circumference in women (beta = 1.11 [0.42-1.80]) and men (beta = 1.33 [0.46-2.19]). Dietary energy density was also independently associated with elevated fasting insulin (beta = 0.65 [0.18-1.12]) and the metabolic syndrome (prevalence ratio = 1.10 [95% CI 1.03-1.17]). CONCLUSIONS: Dietary energy density is an independent predictor of obesity, elevated fasting insulin levels, and the metabolic syndrome in U.S. adults. Intervention studies to reduce dietary energy density are warranted.

Adult↗
PubMed2006

Early television viewing is associated with protesting turning off the television at age 6.

BACKGROUND: The effects of early exposure to television remain poorly defined. Although some have speculated that television may be habit-forming, evidence is lacking especially in young children. OBJECTIVE: To test the hypothesis that television viewing in the first 4 years of life is associated with protesting having the television turned off at age 6. METHODS: We used data from the National Longitudinal Survey of Youth. Parents reported how much television their children watched before the age of 4. They also reported how often their children protested having the television turned off at age 6. Their responses to this question were dichotomized to almost never vs other. Multivariate logistic regression was used to test the independent association of early television watching with subsequent protest at turning off the television, controlling for externalizing behavior scores at age 6, parenting style, and other covariates. RESULTS: Data were available for 1331 children. Sixty-three percent of children protested having the television turned off at age 6. In a logistic regression model, hours of television viewed per day before age 4 was associated with increased odds of protesting at age 6 (1.08 [1.02-1.15]). CONCLUSION: Early television exposure is associated with resistance to turning off the television at school age.

Age Factors↗
PubMed2006

Pediatricians' clinical decision making: results of 2 randomized controlled trials of test performance characteristics.

OBJECTIVE: To determine whether presenting test performance characteristics influences clinical management. DESIGN: Two questionnaire-based, randomized controlled trials. SETTING: Mailed surveys with 2 clinical vignettes. PARTICIPANTS: Randomly selected US pediatricians (N=1502). INTERVENTION: Vignette-specific, randomly assigned test information: no additional information (control), test characteristics (TC), or TC defined. In the pertussis vignette, the TC group received the direct fluorescent antibody test's sensitivity and specificity, and the TC defined group received the same information with definitions. In the urinalysis vignette, the TC group received the false-positive rate of persistent microhematuria in predicting renal disease, and the TC defined group received a definition of this information. MAIN OUTCOME MEASURES: In the pertussis vignette, diagnostic test choice and management of erythromycin therapy and hospital discharge plans. In the urinalysis vignette, serum laboratory testing and nephrology referral plans. RESULTS: Six hundred fifty-three participants (49.5% of those eligible) returned completed surveys. In the pertussis vignette, significantly more of the TC (73%) and TC defined (71%) groups ordered the best-performing test than did controls (21%) (P<.001 for both comparisons). Receiving test characteristics did not significantly affect erythromycin therapy or hospital discharge plans (P>or=.40). In the urinalysis vignette, the TC defined group referred to nephrology (30%) and checked laboratory tests (88%) significantly more often than did controls (19%, P=.01; 78%, P=.01, respectively), but the TC and control groups' testing and referral plans did not differ significantly (22% vs 19%, P=.36; 75% vs 78%, P=.48, respectively). CONCLUSION: Providing test performance characteristics influenced certain clinical decisions, sometimes in unexpected ways.

Adult↗
PubMed2006

Systematic review of the relationship between early introduction of solid foods to infants and the development of allergic disease.

OBJECTIVE: To assess the evidence that early solid feeding (before age 4 months) increases the risk of allergic disease. DATA SOURCES: MEDLINE, the Cochrane Library, and the Drugs and Pharmacology section of EMBASE with key words "infant," "food," and "allergy." STUDY SELECTION: We found 2719 article citations and reviewed references of relevant articles. We critically evaluated the methods and results of articles that met inclusion criteria. We identified 13 studies that met inclusion criteria. There was only 1 controlled trial. DATA EXTRACTION: Allergic disease. DATA SYNTHESIS: Five studies found a positive association between early solid feeding and eczema, with a persistence of the association for 10 years in 1 study. Four studies found no association. One study found an association between early solid feeding and pollen allergy. We found no strong evidence to support the association between early solid feeding and the development of persistent asthma, persistent food allergy, allergic rhinitis, or animal dander allergy. CONCLUSIONS: Systematic review of available evidence suggests that early solid feeding may increase the risk of eczema. However, there are little data supporting an association between early solid feeding and other allergic conditions. Since many studies had problematic methods, additional controlled trials are needed to help guide physicians as they advise parents about the allergic risks of early introduction of solids.

Eczema↗
PubMed2006

Primary language of parent is associated with disparities in pediatric preventive care.

OBJECTIVES: To determine whether infants of parents whose primary language is not English are less likely to receive recommended preventive care than infants of parents whose primary language is English. STUDY DESIGN: We conducted a retrospective cohort study of all 38,793 1-year-old Medicaid-enrolled infants born in Washington state between January 1, 1999 and September 30, 2000. The main exposure was self-reported primary language of parents. Using multivariate regression, we estimated the relative risk of receiving appropriate and timely receipt of preventive care visits in the first year as recommended by the American Academy of Pediatrics and Washington state Medicaid. RESULTS: Fewer than 1 in 6 (15.4%) infants received all 6 recommended preventive care visits in their first year of life. Infants of parents whose primary language was not English were half as likely to receive all recommended preventive care visits compared with infants of parents whose primary language was English (adjusted relative risk = 0.53; 95% confidence interval = 0.49 to 0.58). This disparity was seen in white, Hispanic, and African-American infants, but not in Asian-American infants. CONCLUSIONS: Disparities based on primary language exist in receipt of recommended pediatric preventive care in white, Hispanic, and African-American infants enrolled in Medicaid.

Child Health Services↗
PubMed2006

Publication ethics: editors' perspectives.

The medical literature serves a critical role in the translation of evidence into practice. Although the ethics of research conduct receive considerable attention, much less attention has been focused on the ethics of the publication process. Given how important the process is to the advancement of medicine, this oversight seems unfortunate. This article reviews several salient ethical challenges from the perspective of two editors of a pediatric journal.

Decision Making↗
PubMed2006

Dietary energy density is associated with selected predictors of obesity in U.S. Children.

Increasing rates of childhood overweight have been linked to the rising energy density of the diet. We sought to provide temporal profiles of dietary energy density (DED) in a nationally representative sample of U.S. children and adolescents < or = 19 y old and to describe associations between DED and predictors of overweight. We used a subset of data from the 1994-1996, 1998 Continuing Survey of Food Intake for Individuals (CSFII) and a multivariate regression model to determine independent associations between DED and socioeconomic and demographic variables after controlling for covariates. In this cross-sectional data set, DED was positively associated with total energy intakes and varied with both age and gender. DED increased from birth, peaked at 7-8 y of age, and then declined. Boys consumed more energy-dense diets than girls. Among children < or = 4 y old, higher DED was associated in the regression model with lower household incomes and with enrollment in the food stamp program. Among adolescents 12-19 y old, higher DED was associated with being African-American. In contrast, lower DED among children < or = 11 y old was associated with being Asian or Hispanic and with total daily consumption of fluid milk. The quality of the diet for young children, as indexed by high DED, may be adversely affected by limited household economic resources. Although food insecurity and WIC enrollment were not associated with DED in this study sample, milk consumption in children < or = 4 y old was associated with lower DED.

Adolescent↗
PubMed2006

Prevention of deaths from harmful drinking in the United States: the potential effects of tax increases and advertising bans on young drinkers.

OBJECTIVE: Harmful alcohol consumption is a leading cause of death in the United States. The majority of people who die from alcohol use begin drinking in their youth. In this study, we estimate the impact of interventions to reduce the prevalence of drinking among youth on subsequent drinking patterns and alcohol-attributable mortality. METHOD: We first estimated the effect of public health interventions to decrease harmful drinking among youth from literature reviews and used life table methods to estimate alcohol-attributable years of life lost by age 80 years among the cohort of approximately 4 million U.S. residents aged 20 in the year 2000. Then, from national survey data on transitions in drinking habits by age, we modeled the impact of interventions on alcohol-attributable mortality. RESULTS: A tax increase and an advertising ban were the most effective interventions identified. In the absence of intervention, there would be 55,259 alcohol-attributable deaths over the lifetime of the cohort. A tax-based 17% increase in the price of alcohol of dollar 1 per six pack of beer could reduce deaths from harmful drinking by 1,490, equivalent to 31,130 discounted years of potential life saved or 3.3% of current alcohol-attributable mortality. A complete ban on alcohol advertising would reduce deaths from harmful drinking by 7,609 and result in a 16.4% decrease in alcohol-related life-years lost. A partial advertising ban would result in a 4% reduction in alcohol-related life-years lost. CONCLUSIONS: Interventions to prevent harmful drinking by youth can result in reductions in adult mortality. Among interventions shown to be successful in reducing youthful drinking prevalence, advertising bans appear to have the greatest potential for premature mortality reduction.

Adult↗
PubMed2006

State newborn screening in the tandem mass spectrometry era: more tests, more false-positive results.

BACKGROUND: The advent of tandem mass spectrometry has made it possible to test newborns for multiple conditions efficiently. It is not known how state newborn screening programs have changed screening practices in response to this technology and how it affects the number of false-positive test results. METHODS: We obtained data from the National Newborn Screening and Genetics Resource Center regarding the screening practices for each of the 50 states, to determine the number of mandated disorders added to state newborn screening panels between 1995 and 2005. Combining these data with reported specificities from the literature and the number of births in each state, we estimated the number of infants who would have received false-positive results through screening with tandem mass spectrometry in 2005. RESULTS: The average state mandated screening for 5 disorders in 1995 (range: 0-8 disorders). Wyoming was the only state that decreased its panel size over the next decade. Kansas and Texas were the only states that did not add disorders to their panels between 1995 and 2005; the average state added 19. Iowa, Minnesota, Mississippi, South Dakota, and Tennessee each added > or = 40 disorders. Assuming that an individual test for a disorder had a specificity of 99.995%, we estimated that approximately 2575 infants would have received false-positive results through screening with tandem mass spectrometry in 2005. If specificity was assumed to be 99.9%, then the number increased to > 51000. CONCLUSIONS: State newborn screening programs have expanded dramatically in the past decade. Because the benefit of such testing may be unclear in some cases and because the number of infants who may receive false-positive results and may be labeled falsely as having disease is potentially sizeable, a more cautious approach is needed.

Blood Chemical Analysis↗
PubMed2006

Improving pediatric prevention via the internet: a randomized, controlled trial.

BACKGROUND: Innovations to improve the delivery of pediatric preventive care are needed. METHODS: We enrolled children, 0 to 11 years of age, into a factorial, randomized, controlled trial of a tailored, evidence-based, Web site (MyHealthyChild) that provided information on prevention topics before a scheduled well-child visit. There were 2 components of the intervention, namely, parental Web content and provider notification. Parental Web content provided information to parents about prevention topics; provider notification communicated to physicians topics that were of interest to parents. We assigned 887 children randomly to 4 groups (usual care, content only, content and notification, or notification only). Outcomes were determined with telephone follow-up surveys conducted 2 to 4 weeks after the visit. Poisson regression analysis was used to determine the independent effects of each intervention on the number of topics discussed and the number of preventive practices implemented. RESULTS: Parents in the notification/content group and in the notification-only group reported discussing more MyHealthyChild topics with their provider. Parents in the notification/content group and in the content-only group reported implementing more MyHealthyChild topic suggestions (such as use of a safety device). CONCLUSIONS: A Web-based intervention can activate parents to discuss prevention topics with their child's provider. Delivery of tailored content can promote preventive practices.

Child↗
PubMed2006

A systematic review for the effects of television viewing by infants and preschoolers.

OBJECTIVE: The purpose of this work was to conduct a systematic review of experimental trials for the effects of television viewing by infants and preschoolers. METHODS: Searches were conducted as of January 2005 on several online bibliographic databases for the disciplines of medicine, psychology, education, and communications. Relevant bibliographies were also reviewed. The article contents were critically evaluated to determine whether they met inclusion criteria. Data were extracted from each included article regarding study methods and results. RESULTS: Twelve controlled trials met all of the criteria for inclusion in this review. All of the studies focused on the effect of television content rather than viewing time. The findings suggest that educational television programs are successful in broadening young children's knowledge, affecting their racial attitudes, and increasing their imaginativeness. There is insufficient experimental evidence for effects of viewing these programs on either children's prosocial behavior or their aggressive behavior. Finally, there is some evidence that viewing cartoons has a negative effect on children's attentional abilities. CONCLUSIONS: A number of gaps remain in the literature. Although the amount of time children spend viewing television raises concern, the studies presented here focus only on content. Despite the fact that infants are the fastest growing television market segment, the controlled trials only include children aged > or = 3 years. Finally, the clinical utility of the findings are questionable given that most studies included small group sizes, all took place in nonnaturalistic settings, and all but 1 study only evaluated short-term effects of television viewing.

Child Behavior↗
PubMed2005

Hospital characteristics associated with the management of pediatric splenic injuries.

CONTEXT: Despite evidence that more than 90% of children with traumatic injuries to the spleen can be successfully managed nonoperatively, there is significant variation in the use of splenectomy. As asplenic children are at increased risk of overwhelming postsplenectomy infection, nonoperative management may be considered a quality of care indicator. OBJECTIVE: To test the hypothesis that children are more likely to undergo splenectomy in general hospitals than in children's hospitals. DESIGN: Retrospective cohort study using data from the Kid's Inpatient Database (KID) for the year 2000. Multivariable regression was used to control for patient and hospital characteristics. SETTING AND PARTICIPANTS: All children aged 0 to 16 years who were hospitalized with a traumatic (noniatrogenic) spleen injury in nonfederal short-stay hospitals in any of the 27 states participating in KID (N = 2851). MAIN OUTCOME MEASURE: Splenectomy performed within 1 day of arrival. RESULTS: A total of 11 children (3%) with splenic injuries receiving care at children's hospitals underwent splenectomy compared with 383 children (15.4%) cared for at general hospitals (P<.001). After adjusting for patient characteristics, injury severity, and hospital characteristics, splenectomy was more likely among children treated at general hospitals (odds ratio, 5.01; 95% confidence interval, 2.21-11.36) than among children treated at children's hospitals. CONCLUSIONS: There is considerable variation in the management of pediatric splenic injuries, with significantly lower rates of splenectomy at designated children's hospitals. Quality improvement interventions, including increased education and training for physicians in general hospitals, may be needed to increase the use of spleen-conserving management practices.

Adolescent↗
PubMed2005

Early cognitive stimulation, emotional support, and television watching as predictors of subsequent bullying among grade-school children.

BACKGROUND: Bullying is a major public health issue, the risk factors for which are poorly understood. OBJECTIVE: To determine whether cognitive stimulation, emotional support, and television viewing at age 4 years are independently associated with being a bully at ages 6 through 11 years. METHODS: We used multivariate logistic regression, using data from the National Longitudinal Survey of Youth, to adjust for multiple confounding factors. RESULTS: Parental cognitive stimulation and emotional support at age 4 years were each independently protective against bullying, with a significant odds ratio of 0.67 for both variables associated with a 1-SD increase (95% confidence interval, 0.54-0.82 for cognitive stimulation and 0.54-0.84 for emotional support). Each hour of television viewed per day at age 4 years was associated with a significant odds ratio of 1.06 (95% confidence interval, 1.02-1.11) for subsequent bullying. These findings persisted when we controlled for bullying behavior at age 4 years in a subsample of children for whom this measure was available. CONCLUSION: The early home environment, including cognitive stimulation, emotional support, and exposure to television, has a significant impact on bullying in grade school.

Aggression↗
PubMed2005

Children's television viewing and cognitive outcomes: a longitudinal analysis of national data.

OBJECTIVE: To test the independent effects of television viewing in children before age 3 years and at ages 3 to 5 years on several measures of cognitive outcomes at ages 6 and 7 years. DESIGN: Using data from a nationally representative data set, we regressed 4 measures of cognitive development at ages 6 and 7 years on television viewing before age 3 years and at ages 3 to 5 years, controlling for parental cognitive stimulation throughout early childhood, maternal education, and IQ. RESULTS: Before age 3 years, the children in this study watched an average of 2.2 hours per day; at ages 3 to 5 years, the daily average was 3.3 hours. Adjusted for the covariates mentioned earlier, each hour of average daily television viewing before age 3 years was associated with deleterious effects on the Peabody Individual Achievement Test Reading Recognition Scale of 0.31 points (95% confidence interval [CI], -0.61 to -0.01 points), on the Peabody Individual Achievement Test Reading Comprehension Scale of 0.58 points (95% CI, -0.94 to -0.21 points), and on the Memory for Digit Span assessment from the Wechsler Intelligence Scales for Children of -0.10 points (95% CI, -0.20 to 0 points). For the Reading Recognition Scale score only, a beneficial effect of television at ages 3 to 5 years was identified, with each hour associated with a 0.51-point improvement in the score (95% CI, 0.17 to 0.85 points). CONCLUSIONS: There are modest adverse effects of television viewing before age 3 years on the subsequent cognitive development of children. These results suggest that greater adherence to the American Academy of Pediatrics guidelines that children younger than 2 years not watch television is warranted.

Adolescent↗
PubMed2005

Cigarette tax increase and media campaign cost of reducing smoking-related deaths.

BACKGROUND: Tobacco use results in 500,000 premature deaths annually. Most smokers begin using tobacco before age 21, so the greatest impact on preventing smoking-related mortality is likely to come from campaigns targeting youths. This study estimates the cost-effectiveness of an anti-smoking media campaign and dollar 1 per pack increase in cigarette taxes on the lifetime decrease in smoking-attributable mortality among the cohort of all 18-year-olds in the United States during the year 2000. METHODS: Cost-effectiveness analysis conducted from a societal perspective. RESULTS: The combined effects of a media campaign and dollar 1 per pack tax increase will result in a societal savings of between dollar 590,000 per life-year saved, at a 3% discount rate and dollar 1.4 million per life year saved, at a 7% discount rate. CONCLUSIONS: A media campaign and $1 per pack cigarette tax increase will reduce overall smoking prevalence, significantly decrease smoking-attributable mortality, and decrease net societal costs.

Adolescent↗