This study, which took advantage of California’s statewide natural experiment, did not find that notifying parents of school-based BMI screening results for 5th
grade students had an effect on pediatric obesity. While notifying parents of their child’s weight status might be part of a multi-faceted approach to reducing obesity, these results suggest that current notification methods in 5th
grade are not sufficiently effective to warrant the practice on a large scale. California, which is home to almost 1 in 8 youth living in the United States, has the largest Latino population in the country.17
This study, therefore, provided a unique opportunity to evaluate the impact of school-based BMI screening and notification in one of the ethnic groups most susceptible to obesity and type 2 diabetes.18
Theoretically, BMI screening and reporting can notify parents that their child is overweight or obese and prompt them to act on this knowledge. There is consistent evidence demonstrating that many parents of overweight and obese children aren’t cognizant of their child’s weight status.19
However, perceptions of weight status and the risks associated with obesity are complex and may not be changed by experts’ reports of risk.20
Many adults who are obese or otherwise at risk for cardiovascular disease do not perceive themselves to be at increased risk, despite experts’ opinions to the contrary.21, 22
The long-term risks of childhood obesity are particularly difficult to convey as parents frequently believe their child will “grow into their weight.”23
Two studies have demonstrated that BMI reporting can improve the accuracy of parents’ perceptions of their child’s weight status.24, 25
West et al demonstrated this effect among both African American and white parents.25
Chomitz et al further found that parents of children in Kindergarten through 8th
grade reported being motivated to attempt lifestyle changes as a result of BMI reporting,24
though it should be noted that the parents in Chomitz’s study were of relatively high socioeconomic status. Also noteworthy is the fact that in Chomitz’s study, 1 to 6 weeks after a BMI report was sent, only 63% of parents recalled having received the report, suggesting that BMI reporting may be a weak intervention. In a large-scale effort among a diverse population in West Virginia, Harris et al found that BMI reporting did not change parents’ perceptions of their child’s weight.26
Further work to enhance the impact of BMI reporting should explore parents’ perceptions of the causes of obesity, its associated risks, and what can and should be done at the individual, family, and community levels. This “mental models” approach has been successfully used to improve risk communications in other arenas.27
A better understanding of parents’ mental models might suggest communication methods to provide critical missing information and dispel misconceptions around pediatric obesity that affect parents’ willingness or ability to make changes. It will be particularly important to explore mental models among distinct race/ethnic and socioeconomic subgroups, given these factors’ impact on weight perception.28
Even if BMI reporting can alter perceptions in diverse groups, school-based BMI reporting fails one of the most salient aspects of a useful screening test: having an effective therapy if the disease (or condition) is detected.29
Lifestyle interventions to treat pediatric obesity are largely ineffective30
and recommending individual behavior change is unlikely to meet with success, if the experience of multidisciplinary pediatric obesity clinics is any guide.31,32
Thus, expecting a single BMI report to parents to have a meaningful effect on a child’s weight status, in the absence of environmental changes, may be wishful thinking.
Arkansas did see a halt in the progression of obesity after implementing BMI screening and notification as part of Act 1220 of 2003.33
However, Act 1220 simultaneously called for changes in cafeteria food offerings, increased physical activity requirements, and healthier vending machine options, making attribution to any one intervention difficult. A recent study employing a similar multi-faceted approach to alter the school environment demonstrated a significant impact on obesity, without implementing BMI screening and notification.34
There is evidence that focused interventions can have a positive impact on pediatric obesity. For example, policies banning the sale of sugar-sweetened beverages and snacks high in fat or sugar during the school day appear to be related to declines in obesity seen after 2005 in California.35
Increased quality and quantity of physical education has been associated with decreased obesity and improved fitness.36–38
Until a cost-effective method of BMI notification can be found, notification resources would be better invested in changing youths’ environment, particularly in low-income communities.
The present study could not assess the impact of BMI screening itself, and it is possible that screening alone may heighten community awareness, which, in turn, could lead to changes in school or community policies over a period of years. These changes might have an impact on obesity that our model, which looked to see if notification predicted weight status 2 years hence for a cohort of children, could not detect. It will be important to study the impact of screening itself on obesity.
Several limitations should be considered in interpreting these findings. Misclassification of the predictor variable, which would decrease our ability to see an effect of BMI reporting, could occur if institutional memory is poor or if individual schools deviate from the district policy regarding notification. Additionally, if students changed districts between 5th and 9th grade and notification status differed between the old and new districts, their data would be misclassified. Sensitivity analyses to address misclassification (limiting data to the most recent years, excluding districts indicating that individual schools might deviate from district policy, and excluding districts with high mobility) yielded similar findings. Parents who did not receive results as intended would be misclassified, and sensitivity analyses would not address this.
We could not link data across years for individual students and while it would be unusual, associations at the student level could be different from those at the district level, due to confounding at either the student or district level. Data were differentially missing for districts with heavier students and districts with a higher proportion of students eligible for free meals; however, notification status did not modify this association so it is unlikely that this bias in missing data would affect our findings beyond potentially limiting generalizability.
The quality of school-based BMI screening data is unknown. There is no surveillance of FITNESSGRAM test administration, and the integrity of data collection methods likely vary (which will decrease precision of estimates), and may vary by school (which might bias results). Nonetheless, random error is not likely an issue given our very small 95% CI for the effect. Bias in measurements is possible, but unless there is also bias in the change over time, it should not affect our results for the effect of notification.
The widespread use of BMI screening and reporting is heartening as it reflects schools’ willingness to dedicate resources to address the obesity epidemic. However, current methods of reporting school-based BMI screening results to parents do not appear to have an impact on pediatric obesity. While BMI screening itself may have value, further work to evaluate different approaches to providing parents with BMI screening information should be pursued before BMI reporting is implemented on a large scale. In addition, research could explore how this type of information might be used more broadly with other stakeholders and in policy. In the meantime, schools will likely see greater benefits if resources are used to increase opportunities for physical activity and improve nutrition.