Assessment of Body Mass Index Screening of Elementary School Children --- Florida, 2007--2008

The prevalence of childhood obesity has increased substantially in the United States and is associated with chronic diseases (1). State level surveillance is needed to monitor trends and investigate risk factors. In addition, data that identify at-risk communities can be used to inform those communities regarding childhood obesity. Body mass index (BMI) screening of Florida school children has been performed since 2001 as part of growth and development screening services and conducted by school districts and county health departments. Aggregated BMI data, by grade and county, are reported annually to the Florida Department of Health (FDOH). In 2008, FDOH considered establishing a more extensive statewide BMI surveillance system. To begin planning for such a system, during February--March 2008, FDOH surveyed school health coordinators in Florida's 67 counties to assess qualities of BMI screening activities. Among 66 counties that provided complete surveys, 58 (88%) screened ≥75% of children in the first, third, and sixth grades, and 51 (77%) had written protocols or guidelines for measuring weight, height, or BMI. Nineteen counties (29%) were training ≥90% of their screeners, and 21 (32%) consistently used appropriate equipment for measuring height and weight. Thirty-one counties (47%) used appropriate electronic systems to calculate BMI percentile-for-age. BMI screening activities need improvement in policy and guideline development, training procedures, appropriate selection and use of equipment, and use of electronic data systems before Florida establishes a more extensive statewide surveillance system.

Since 1974, Florida statutes* have required that county school health programs provide growth and development screening services. Florida's administrative code† specifies that growth and development screenings be performed for students in the first, third, sixth, and optionally, ninth grades. In 2000, CDC released new growth charts§ based on BMI and recommended their use to identify underweight (<5th percentile BMI), overweight (85th to <95th percentile), or obese (≥95th percentile) children. Based on this recommendation, the Florida School Health Service Program (FSHSP) has been using the CDC growth charts with BMI percentile for age and sex as the reference to determine BMI categories (underweight, normal, overweight, and obese) since 2001. Currently, the state is allowed only to collect aggregated numbers of students and prevalence for each BMI category by grade and county; aggregated data are reported annually to FSHSP as required by FDOH policy. FSHSP provides oversight of school health policies and procedures, quality assurance, and training to counties regarding school health issues. FSHSP also provides recommended BMI screening procedures for county school health programs by way of the state administrative guidelines. Most county school health programs inform parents of the BMI results.

FDOH developed a survey for school health coordinators in all of the 67 school districts and county health departments. The survey was conducted by e-mailing an electronic survey link to identified coordinators during February and March 2008. The survey included questions about BMI screening activities, including existence of policies and guidelines (having a written policy or guidelines for measuring student height, weight, or BMI); screening rates (percentage range of students receiving height and weight measurements for each grade); types of equipment used to measure height and weight; use of electronic data collection systems; organizational priority of childhood obesity ("Is childhood obesity a priority for your school district? ...county health department?"); and staff training requirements (percentage of screeners who received training in measurement methods).

To measure the quality of policies and guidelines, 13 components were assessed: staff qualification, staff training requirements, staff supervision, screening environment, appropriate equipment, recalibration of equipment, screening methodology, removal of student's shoes or heavy clothing before measurement, BMI calculation, confidentiality of screening records, and follow-up specifications for children with unhealthy weight (underweight or overweight/obese).

For the analysis, county population size was defined as small (<150,000 persons), medium (≥150,000 to <500,000 persons), and large (≥500,000 persons). Chi-square test was used to test differences within categories. A p-value ≤0.05 was considered as statistically significant.

All 67 Florida counties responded to the survey. One county was excluded because of incomplete responses. Of the 66 counties included in the analysis, all reported screening of first and third graders, and 64 counties screened sixth graders. Reasons for not screening all students in grades specified by the Florida administrative code generally related to lack of resources. Among the 66 counties, 58 (88%) screened ≥75% of students in first, third, and sixth grades (Table). Screening completion rates varied by county population size. Almost all small counties (36 of 37 counties, 97%) screened ≥75% of students for BMI in first grade, compared with 89% (16 of 18 counties) of medium counties and 73% (eight of 11 counties) of large counties (chi-square test, p=0.04). All 37 (100%) small counties screened ≥75% of students in third grade compared with 89% (16 of 18 counties) of medium counties and 73% (eight of 11 counties) of large counties (p=0.009).

Fifty-one of 66 counties (77%) had policies or guidelines for measuring students' weight, height, or BMI percentile. Of those 51 counties, 36 (71%) reported completing ≥90% of BMI screening activities in compliance with the policies or guidelines. Smaller counties were more likely to follow their policies or guidelines than were larger counties (p=0.03).

Nineteen of 66 counties (29%) trained ≥90% of screeners before student screening by demonstrating how to conduct measurements and by directly observing trainees in screening activities. Twenty-eight counties (42%) used stadiometers appropriate for measuring height for all children, 43 counties (65%) used a professional-grade digital scale or a triple balance beam scale appropriate for measuring weight for all children, and 21 counties (32%) used appropriate equipment for measuring height and weight. Smaller counties were more likely to use an appropriate stadiometer or weight scale than were larger counties (p<0.01).

Thirty-one counties (47%) used an acceptable electronic data system, defined as using School Health Information Program, Health Master, Epi-Info/Nutstat, or bmi4kidz, to calculate BMI percentile. Smaller counties were more likely to use an acceptable electronic data system to calculate BMI percentile than were larger counties (p=0.04). Only 22 counties (33%) identified obesity as a high priority for both their school district and county health department.

Reported by: R Evans, MPH, Collier County Health Dept, W Sappenfield, MD, M Oxamendi, C Vickers, Div of Family Health Svcs, Florida Dept of Health. B Sherry, PhD, Div of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion; D Bensyl, PhD, Career Development Div, Office of Workforce and Career Development; S Park, PhD, EIS Officer, CDC.

Editorial Note:

The prevalence in the United States of children being overweight or obese (BMI ≥85th percentile for age and sex) increased from 30% in 1999--2000 to 33% in 2003--2006 among children aged 6--11 years (1). BMI percentile is widely used to monitor obesity status among children because of its simplicity and low cost, and because BMI is an indicator of body fat in children (2). Childhood obesity has been associated with adverse physical and mental health risks among children (3) and is a predictor of adulthood obesity (4,5). Current effective prevention strategies focus on multiple levels, including community, school, and family (6). Monitoring childhood obesity trends at the state and local level provides important information for developing and implementing successful strategies and interventions. Intervention strategies include policy and environmental changes that promote healthy dietary habits and increased physical activity to reduce the high prevalence of childhood obesity. Accurate measurements of height and weight and correct calculation for BMI percentile among school-aged children are necessary to provide quality BMI data, ensure appropriate screening and referral, and ultimately initiate a high quality BMI surveillance system for use locally and statewide. Accurate surveillance data can be used for identifying obesity trends in populations and monitoring the outcomes of interventions (7).

The findings of this report indicate that BMI screening activities among school-aged children in Florida did not meet sufficient quality measures regarding policies and guidelines, screening practices, staff training, equipment, and data management. In general, the quality of BMI screening activities was higher in counties with lower population size than in those with larger populations. The reasons for this are not fully clear, but one factor might be the increased complexity of performing appropriate BMI screening in counties with larger school systems compared to counties with smaller systems.

Based on the survey findings in this report, FSHSP is addressing quality and performance issues in several ways. FSHSP reviewed and strengthened the school health policy on BMI screening, revised BMI reporting requirements to better monitor performance, and worked with county school health programs to address identified issues.

The findings in this report are subject to at least two limitations. First, survey results were obtained from the lead school health coordinator in each county and might not reflect actual practice at the schools. In addition, actual student BMI data were not verified for quality and reliability.

Ultimately, to further understand the epidemiology of obesity in Florida, a more extensive BMI surveillance system will be needed, including a statewide repository of de-identified individual BMI screenings. To do this, additional controls and resources will be needed to ensure the accuracy and reliability of BMI screenings. Additional evaluations of the appropriateness of BMI screening activities in Florida school districts can help ensure the accuracy of statewide data.

Acknowledgment

This report is based, in part, on contributions of Florida school health coordinators in each of Florida's 67 counties who completed the survey.

References

1. Ogden CL, Carroll MD, Flegal KM. High body mass index for age among US children and adolescents, 2003--2006. JAMA 2008;299:2401--5.
2. Zimmermann MB, Gübeli C, Püntener C, Molinari L. Detection of overweight and obesity in a national sample of 6--12-y-old Swiss children: accuracy and validity of reference values for body mass index from the US Centers for Disease Control and Prevention and the International Obesity Task Force. Am J Clin Nutr 2004;79:838--43.
3. Adair LS. Child and adolescent obesity: epidemiology and developmental perspectives. Physiol Behav 2008;94:8--16.
4. Deckelbaum RJ, Williams CL. Childhood obesity: the health issue. Obes Res 2001;9(Suppl 4):239--43S.
5. Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting obesity in young adulthood from childhood and parental obesity. N Engl J Med 1997;337:869--73.
6. Institute of Medicine. Preventing childhood obesity: health in the balance. Washington, DC: National Academies Press; 2005.
7. Nihiser AJ, Lee SM, Wechsler H, et al. Body mass index measurement in schools. J Sch Health 2007;77:651--71.

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Date last reviewed: 5/7/2009