Adequacy of two ambulatory care surveillance systems for tracking childhood obesity practice patterns

The National Ambulatory Medical Care Surveys (NAMCS) and National Hospital Ambulatory Medical Care Surveys (NHAMCS) are surveillance systems in the USA that track provider practice patterns at ambulatory care visits. This study investigated the adequacy of the NAMCS/NHAMCS for surveillance of childhood obesity practice patterns.

The frequency of obesity visits in the 1997-2000 NAMCS/NHAMCS (outpatient component) was compared with obesity prevalence among children who reported a physician visit in the preceding 12 months in the National Health and Nutrition Examination Survey (NHANES) 1999-2000. Obesity was identified using the International Classification of Diseases 9th revision clinical modification code ICD-9-278.0 in the NAMCS/NHAMCS. For the NHANES, age- and gender-specific body mass index >95th percentile was used.

Between 1997 and 2000, obesity was identified in 4.1 million (0.8%) of 516 million ambulatory care visits. With an obesity prevalence of 14.2% from the NHANES survey, NAMCS/NHAMCS only identified 5.6% of all children aged 2-17 years >95th percentile. Of those identified, the rate of obesity visits in the NAMCS/NHAMCS was lowest for non-Hispanic Whites (3.9%) compared with non-Hispanic Blacks (6.9%) and Hispanics (10.2%).

The very infrequent reporting of obesity in the NAMCS/NHAMCS suggests that these surveillance systems do not reflect how healthcare providers identify and care for overweight children. Collecting weight and height measures would improve their utility in tracking identification and management of overweight children.