Urban Park Development and Pediatric Obesity Rates: A Quasi-Experiment Using Electronic Health Record Data.

INTRODUCTION: Childhood obesity affects ~20% of children in the United States. Environmental influences, such as parks, are linked with increased physical activity (PA). OBJECTIVE: To examine whether changes in Body Mass Index (BMI) z-score were associated with construction of a new park. METHODS: A quasi-experimental design was used to determine whether living in proximity of a park was associated with a reduction in BMI z-score. Children were selected from health clinics within an 11 mile radius of the park. A repeated-measure ANOVA was employed for analysis of the relationship between exposure (new park) and BMI z-score. RESULTS: Participants were 1443 (median age 10.3 range (2-17.9 years), BMI: z-score 0.84 ± 1.09) African American (77.4%) adolescents. Change in BMI z-score was not statistically different for children living at different distances from the park after controlling for age, gender, race, ethnicity, or payer type (p = 0.4482). We did observe a small 0.03 increase in BMI z-score from pre- to post-park (p = 0.0007). There was a significant positive association between child's baseline age and BMI z-score (p < 0.001). CONCLUSIONS: This study found proximity to a park was not associated with reductions in BMI z-score. Additional efforts to understand the complex relationship between park proximity, access, and PA are warranted.

Regression to the Mean: A Commonly Overlooked and Misunderstood Factor Leading to Unjustified Conclusions in Pediatric Obesity Research.

OBJECTIVE: In this paper we discuss what regression to the mean (RTM) is, the magnitude of RTM in realistic situations, interpretation of RTM, and recommendations for how to address RTM in study design. METHODS: Public health research faces many challenges in conducting gold standard randomized, controlled trials (RCT). Although there are many threats to validity in uncontrolled trials, RTM is often overlooked or not adequately considered. RTM is a statistical phenomenon that occurs with any pair of variables that have a correlation not equal to |1.0|. With RTM, subjects' average values on an outcome variable (e.g., BMI) change in a systematic direction over time despite there being no treatment effect. Without a proper control group, changes thought to be associated with an intervention may be due entirely to RTM. Investigators may draw erroneous conclusions based on results showing greater declines in a variable among participants with higher baseline of that variable compared to those with lower baseline of that variable, and label this evidence for differential treatment efficacy. CONCLUSIONS: Ignoring RTM can lead to unsubstantiated conclusions about the effects of treatments. These conclusions can lead to the waste of time, money, and other resources, which distract from finding appropriate interventions. When a true RCT design is not feasible, reasonable design alternatives involving nonrandomized control groups should be implemented.

Gestational and postpartum weight change patterns in mothers with eating disorders.

BACKGROUND: Although pregnancy can be associated with adaptive changes in weight and eating behaviour for women with eating disorders, less is known about whether these changes are maintained in the postpartum period. We used a longitudinal design to examine gestational and postpartum weight trajectories in mothers with and without eating disorders in the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. METHODS: Fifty-six women reported anorexia nervosa (AN), 636 bulimia nervosa, 3327 binge eating disorder and 69 eating disorder not otherwise specified, purging type. The referent group included 61,233 mothers with no eating disorder. We used a mixed effects model to predict weight change over time by eating disorder subtype. RESULTS: Mothers with AN, bulimia nervosa, binge eating disorder and eating disorder not otherwise specified had greater increases in body mass index (BMI) during pregnancy and greater decreases in BMI over the first 6 months postpartum. Women with AN shifted from the underweight BMI range before pregnancy to the normal weight range at 36 months postpartum CONCLUSIONS: Patterns of maternal weight gain and retention during the perinatal period vary across eating disorder subtype and warrant clinical attention.

Systems science and childhood obesity: a systematic review and new directions.

As a public health problem, childhood obesity operates at multiple levels, ranging from individual health behaviors to school and community characteristics to public policies. Examining obesity, particularly childhood obesity, from any single perspective is likely to fail, and systems science methods offer a possible solution. We systematically reviewed studies that examined the causes and/or consequences of obesity from a systems science perspective. The 21 included studies addressed four general areas of systems science in obesity: (1) translating interventions to a large scale, (2) the effect of obesity on other health or economic outcomes, (3) the effect of geography on obesity, and (4) the effect of social networks on obesity. In general, little research addresses obesity from a true, integrated systems science perspective, and the available research infrequently focuses on children. This shortcoming limits the ability of that research to inform public policy. However, we believe that the largely incremental approaches used in current systems science lay a foundation for future work and present a model demonstrating the system of childhood obesity. Systems science perspective and related methods are particularly promising in understanding the link between childhood obesity and adult outcomes. Systems models emphasize the evolution of agents and their interactions; such evolution is particularly salient in the context of a developing child.

Healthy for now? A cross-sectional study of the comorbidities in obese preschool children in the United States.

OBJECTIVE: Examine health of preschoolers by BMI status. METHODS: A cross-sectional analysis of children 3 to 5 years old in the 1999-2008 National Health and Nutrition Examination Survey was carried out. The measured age- and sex-specific BMI percentiles were used to categorize children as very obese, obese, overweight, or healthy weight. The authors used logistic regression to examine the effect of weight status on 17 available measures of current child health potentially related to obesity. RESULTS: Except for very obese children, weight status had minimal effect on most measures of health for preschool-aged children (n = 2792). Parents of very obese children reported poorer general health and more activity limitations for their children. Additionally, very obese girls had more frequent/severe headaches, and overweight/obese boys had more asthma diagnoses. CONCLUSIONS: Only severe obesity appears consistently related to immediate health problems in preschool-aged children. Parental perception that very obese children have worse health and more activity limitations may lead to decreases in physical activity, which would perpetuate obesity.