Sensitivity and specificity of obesity diagnosis in pediatric ambulatory care in the United States.

Objective: We examined the sensitivity and specificity of an obesity diagnosis in a nationally representative sample of pediatric outpatient visits.

Methods: We used the 2005 to 2009 National Ambulatory Medical Care and National Hospital Ambulatory Medical Care surveys. We included visits with children 2 to 18 years, yielding a sample of 48 145 database visits. We determined 3 methods of identifying obesity: documented body mass index (BMI) ≥95th percentile; International Classification of Diseases, Ninth Revision (ICD-9) code; and positive answer to the question, "Does the patient now have obesity?" Using BMI as the gold standard, we calculated the sensitivity and specificity of a clinical obesity diagnosis.

Results: Among the 19.5% of children who were obese by BMI, 7.0% had an ICD-9 code and 15.2% had a positive response to questioning. The sensitivity of an obesity diagnosis was 15.4%, and the specificity was 99.2%.

Conclusions: The sensitivity of the obesity diagnosis in pediatric ambulatory visits is low. Efforts are needed to increase identification of obese children.