Gender Bias in U.S. Pediatric Growth Hormone Treatment.

Growth hormone (GH) treatment of idiopathic short stature (ISS), defined as height <-2.25 standard deviations (SD), is approved by U.S. FDA. This study determined the gender-specific prevalence of height <-2.25 SD in a pediatric primary care population, and compared it to demographics of U.S. pediatric GH recipients. Data were extracted from health records of all patients age 0.5-20 years with ≥ 1 recorded height measurement in 28 regional primary care practices and from the four U.S. GH registries. Height <-2.25 SD was modeled by multivariable logistic regression against gender and other characteristics. Of the 189,280 subjects, 2073 (1.1%) had height <-2.25 SD. No gender differences in prevalence of height <-2.25 SD or distribution of height Z-scores were found. In contrast, males comprised 74% of GH recipients for ISS and 66% for all indications. Short stature was associated (P < 0.0001) with history of prematurity, race/ethnicity, age and Medicaid insurance, and inversely related (P < 0.0001) with BMI Z-score. In conclusion, males outnumbered females almost 3:1 for ISS and 2:1 for all indications in U.S. pediatric GH registries despite no gender difference in height <-2.25 SD in a large primary care population. Treatment and/or referral bias was the likely cause of male predominance among GH recipients.