Volume 11 — July 10, 2014
ORIGINAL RESEARCH
Severe Obesity Among Children in New York City Public Elementary and Middle Schools, School Years 2006–07 Through 2010–11
| Age Group, y | Prevalenceb | School Year, % | Trend for Timea P value | ||||
|---|---|---|---|---|---|---|---|
| 2006-07 | 2007-08 | 2008-09 | 2009-10 | 2010-11 | |||
| Overall (ages 5–14) | Obesity | 21.90 | 21.40 | 20.90 | 21.00 | 20.70 | <.001 |
| Severe obesity | 6.30 | 6.10 | 5.90 | 5.80 | 5.70 | <.001 | |
| 5–6 | Obesity | 20.20 | 19.40 | 18.80 | 18.40 | 18.20 | <.001 |
| Severe obesity | 4.30 | 4.20 | 3.90 | 3.90 | 3.70 | <.001 | |
| 7–10 | Obesity | 22.90 | 22.70 | 21.80 | 22.20 | 21.80 | <.001 |
| Severe obesityc | 6.80 | 6.50 | 6.20 | 6.20 | 6.00 | .04 | |
| 11–14 | Obesity | 21.80 | 21.00 | 21.10 | 21.10 | 21.10 | <.001 |
| Severe obesity | 7.00 | 6.60 | 6.70 | 6.60 | 6.50 | <.001 | |
Figure 1. Trends in prevalence by age group of severe obesity and obesity (which includes severe obesity) among NYC public school students aged 5 to 14 years in kindergarten through 8th grade, school years 2006–07 through 2010–11. To test for trend over school years, a multivariate model was built that included as covariates a linear term for trend, along with sex; age; race/ethnicity; school borough by district public health office (DPHO) neighborhoods (neighborhoods with low income and disproportionate rates of morbidity and mortality); free-meal status; place of birth; language spoken at home; and an interaction by age, sex, and race/ethnicity. School and student codes were used as cluster variables. All trends were significant at P <.001. Prevalence estimates of obesity (body mass index [BMI] ≥95th percentile) and severe obesity (BMI ≥120% of 95th percentile) are based on valid BMI measurements weighted by race/ethnicity, school borough by DPHO, free-meal status, grade, sex, age, and school type (elementary vs middle) to be representative of the enrollment population for each school year. Adjusted P
value for trend = .04 for severe obesity among the 7 to 10 years age group.
| Race/Ethnicity | Sex | Severe Obesity Prevalence, % | Percentage Point Increase, Severe Obesity Prevalence |
|---|---|---|---|
| Asian/Pacific Islander | Female | 1.37 | 0.10 |
| Male | 3.09 | 0.40 | |
| Hispanic | Female | 5.90 | 0.65 |
| Male | 8.35 | 1.40 | |
| Black | Female | 6.55 | 1.15 |
| Male | 6.38 | 1.53 | |
| White | Female | 2.92 | 0.35 |
| Male | 4.42 | 0.81 |
Figure 2. Potential effect of misclassification of plausible values as biologically implausible on severe obesity prevalence, by race/ethnicity and sex among New York City public school students, grades kindergarten through 8, 2010–11 school year. Prevalence estimates of severe obesity (body mass index [BMI] ≥120% of 95th percentile by age and sex) are based on measurements taken during the 2010–11 school year among students aged 5 to 14 years at the end of the school year. Measurements were weighted by race/ethnicity, school borough by district public health office neighborhoods (neighborhoods with low-income and disproportionate rates of morbidity and mortality), free-meal status, grade, sex, age, and school type (elementary vs middle) to be representative of the enrollment population for the 2010–11 school year. Students categorized as Asian/Pacific Islander, black, or white were all non-Hispanic. Persons categorized as Hispanic were of any race. Biologically implausible values (BIV) records are records identified as BIV for height, weight, weight-for-height, or BMI according to the age- and sex-specific Centers for Disease Control and Prevention's 2000 growth chart z
scores (17) and the World Health Organization’s fixed exclusion range
cut-offs (18), which were further classified into high-BIV if the student’s
records showed a BMI at or greater than 120% of the 95th percentile. To
quantify the upper boundary effect of misclassified BIVs on prevalence
estimates of severe obesity, all high-BIV records were assumed to be
misclassified as BIV for the 2010–11 school year. The high-BIV measurements
were combined with the valid measurements of BMI; these combined records
were reweighted (by using the procedures described above) to be
representative of the enrollment population for the 2010–11 school year.
Prevalence of severe obesity was recalculated including high-BIV records,
and the reported percentages are the increase in prevalence observed from
including high-BIV records. Abbreviation: BMI, body mass index.
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