Underdiagnosis of hypertension in children and adolescents.

CONTEXT: Pediatric hypertension is increasing in prevalence with the pediatric obesity epidemic. Diagnosis of hypertension in children is complicated because normal and abnormal blood pressure values vary with age, sex, and height and are therefore difficult to remember.

OBJECTIVES: To determine the frequency of undiagnosed hypertension and prehypertension and to identify patient factors associated with this underdiagnosis.

DESIGN, SETTING, AND PARTICIPANTS: A cohort study of 14,187 children and adolescents aged 3 to 18 years who were observed at least 3 times for well-child care between June 1999 and September 2006 in the outpatient clinics in a large academic urban medical system in northeast Ohio. For children and adolescents who met criteria for hypertension or prehypertension at 3 or more well-child care visits, the proportion with a hypertension-related International Classification of Diseases, Ninth Revision code in the diagnoses list, problem list, or past medical history list of any visit was determined.

MAIN OUTCOME MEASURES: Proportion of children and adolescents with 3 or more elevated age-adjusted and height-adjusted blood pressure measurements at well-child care visits and with a diagnosis of hypertension or prehypertension documented in the electronic medical record. Multivariate logistic regression identified patient factors associated with a correct diagnosis.

RESULTS: Of 507 children and adolescents (3.6%) who had hypertension, 131 (26%) had a diagnosis of hypertension or elevated blood pressure documented in the electronic medical record. Patient factors that increased the adjusted odds of a correct diagnosis were a 1-year increase in age over age 3 (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.03-1.16), number of elevated blood pressure readings beyond 3 (OR, 1.77; 95% CI, 1.21-2.57), increase of 1% in height-for-age percentile (OR, 1.02; 95% CI, 1.01-1.03), having an obesity-related diagnosis (OR, 2.61; 95% CI, 1.49-4.55), and number of blood pressure readings in the stage 2 hypertension range (OR, 1.68; 95% CI, 1.29-2.19). Of 485 children and adolescents (3.4%) who had prehypertension, 55 (11%) had an appropriate diagnosis documented in the electronic medical record. Patient factors that increased the adjusted odds of being diagnosed with prehypertension included a 1-year increase in age over age 3 (OR, 1.21; 95% CI, 1.09-1.34) and number of elevated blood pressure readings beyond 3 (OR, 3.07; 95% CI, 2.20-4.28).

CONCLUSIONS: Hypertension and prehypertension were frequently undiagnosed in this pediatric population. Patient age, height, obesity-related diagnoses, and magnitude and frequency of abnormal blood pressure readings all increased the odds of diagnosis.