Context: Growth hormone (GH) therapy may improve statural growth outcomes in patients with severe juvenile idiopathic arthritis (JIA).
Objectives: To evaluate the effect of GH treatment on adult height and to identify determinants of growth outcomes in JIA.
Design and patients: Data from 58 patients with JIA, including 53 receiving GH, enrolled in three prospective clinical trials between 1997 and 2002 were analyzed.
Intervention: GH (0.056 mg/kg/d [interquartile range (IQR), 0.050 to 0.062]) for a median duration of 6.5 years (IQR, 4.7 to 7.9 years).
Main outcome measures: Factors associated with a favorable growth outcome (adult height - target height ≤ -1.5 standard deviations) were identified by multivariate logistic regression.
Results: Adult height was available for 48 patients 8.6 years after GH initiation (IQR, 6.0 to 10.2 years). Height standard deviation score (SDS) increased from -2.9 (IQR, -4.4 to -1.6) at baseline to -1.7 (IQR, -3.9 to -0.1) in adulthood (P < 0.001). Median adult height was below target height [SDS, -0.2 (IQR, -1.4 to 0.4); P < 0.001]. Corrected adult height SDS was -1.3 (IQR, -3.0 to -0.2). Growth outcome was favorable in 24 (52.2%) patients. Significant independent determinants of growth outcome were age at GH initiation [adjusted odds ratio (aOR), 0.68 per additional year; 95% confidence interval (CI), 0.47 to 0.99], height at GH initiation (aOR, 2.6 per additional SDS; 95% CI, 1.15 to 5.9), and mean C-reactive protein levels during follow up (aOR, 0.51 per additional 10 mg/L; 95% CI, 0.28 to 0.92).
Conclusion: Long-term GH treatment significantly increased growth in patients with JIA but did not fully restore the genetic growth potential. The response showed marked interindividual variability and was weaker in patients with severe inflammation.
Trial registration: ClinicalTrials.gov NCT00174291 NCT00174187 NCT00174278.
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