NEW ORLEANS — A diagnosis of hypertension was missed in 85% of children with high blood pressure in a study of 287 youngsters who were examined at two university-based, pediatric clinics.
The problem with diagnosing hypertension in kids is that there are too many threshold pressures for most physicians to keep straight, Charlene K. Mitchell, M.D., said at the annual meeting of the Southern Society for Pediatric Research.
Because the threshold for diagnosing hypertension varies by age, height, and gender, there are a total of 420 different diastolic and systolic pressures that determine whether a particular child has high blood pressure, said Dr. Mitchell, a pediatrician and internist at the University of Louisville (Ky.).
The total is 420 because there are 15 different age-specific threshold pressures for children aged 3–17 years, 7 different height-specific threshold pressures between the 5th and 95th height percentiles, different thresholds for girls and boys, and different thresholds for diastolic and systolic pressure.
The threshold criteria for borderline hypertension would add another 120 pressure thresholds for diagnosing hypertension.
“The numbers are chopped up too much. It's far too complex for easy management,” Dr. Mitchell said. “If physicians must always look on a table every time they check a blood pressure, we'll continue to see underdiagnosis.”
Her solution to the number surfeit is to cluster several ages with a single diagnostic pressure threshold. However, eventually she would like to have study results establish pressure thresholds for diagnosing hypertension that are empirically derived, rather than based on statistics. If the diagnostic criteria are simplified, physicians will be much more likely to identify hypertension in children much more often, Dr. Mitchell said.
“We need to be much more aggressive about recognizing hypertension in children than we are now,” she added.
Her study was designed to assess physician accuracy at identifying hypertension in children aged 3–17 years being seen for routine, well-child visits from July 31 to Aug. 15, 2003. Of the 287 children examined, 90 (31%) had hypertension by current standards, and 35 (12%) had borderline hypertension. But only 15% of those with hypertension were diagnosed by their examining physicians.
The results also showed that physicians were more likely to diagnose hypertension in children with a higher body mass index (BMI). The children who were correctly diagnosed as hypertensive were, on average, in the 92nd percentile for BMI. Those who had unrecognized blood pressure elevations were, on average, in the 76th percentile for BMI.