Study design and participants
This multicenter real-world study enrolled children with short stature in 19 hospitals throughout China between January 2015 and December 2017. This study was approved by the Ethics Committees of the Beijing Children’s Hospital, Capital Medical University ([2015]-Y-001-C), and all other participating centers. The study was performed in accordance with the relevant guidelines and regulations. Written informed consents were obtained from all the children and their guardians. The participants were recruited according the criteria of the clinical trial (ClinicalTrials.gov: NCT03249480, 15/08/2017). However, partial participants did not strictly follow the original design of the clinical trial and were treated clinically. Then the physicians and the guardians decided the treatment together as in the real-world clinical practice.
The inclusion criteria were 1) met the diagnosis criteria of short stature, which included: i) absolute height lower than the 3rd percentile of the growth curve of the Chinese children population of the same age and sex, according to the height data reported by the 2005 national survey in China [23], ii) growth velocity (GV) of ≤ 5.0 cm/year, iii) peak plasma GH concentration < 10.0 ng/mL in two stimulation tests with different mechanisms within 1 year before starting treatment, and iv) bone age (BA) ≤ 9 years for girls, and ≤ 10 years for boys, 2) prepubertal status (Tanner stage I), 3) ≥ 3 years old, and 4) did not receive GH treatment within the last 6 months.
The exclusion criteria were 1) liver and/or renal insufficiency with alanine transaminase (ALT) > twofold the upper limit of normal (ULN) or creatinine (Cr) > ULN), 2) positive hepatitis B virus examination including HBcAb, HBsAg, and HBeAg, 3) known highly allergic constitution or allergic to the study drug, 4) diabetes, 5) severe cardiopulmonary diseases, hematological diseases, malignant tumors, systemic infection, immune hypofunction, or psychiatric diseases, 6) other abnormalities in growth and development, including Turner syndrome, Laron syndrome, and GH receptor deficiency, 7) participation in other clinical trials of drugs within the last 3 months, or 8) congenital skeletal dysplasia.
Treatment
All children were treated with PEG-rhGH injection (Jintrolong®; GeneScience Pharmaceuticals, Changchun, China) once per week for 6 months. The individualized dosage was determined by the physicians based on clinical experience, ranging from 0.10 to 0.20 mg/kg/week. The dosages of PEG-rhGH were not adjusted during the treatment period.
Data collection
The clinical data, including sex, age, body temperature, heart rate, respiration, blood pressure, height, weight, and Tanner stage, were collected. The laboratory examination included blood routine test, liver and renal functions, electrolytes, blood lipid, thyroid functions, cortisol, adrenocorticotropic hormone (ACTH), GH stimulation test, insulin-like growth factors-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), anti-hGH antibody, and chromosome karyotypes (for female patients). The imaging examinations included X-ray for BA, anteroposterior and lateral X-ray of the whole spine, and pituitary magnetic resonance imaging (MRI). Electrocardiogram was also monitored.
The height and body weight of the children were measured by specially assigned investigators in each study center, using the specially assigned weighing machine and height-measuring device. The Atlas of Greulich and Pyle was used for the assessment of BA. IGF-1 and IGFBP-3 levels were measured by the chemiluminescence method (Immulite 2000 analyzer; Siemens, Erlangen, Germany). The children were carefully followed up and examined before, during, and after treatment, and the indicators of effectiveness and safety were monitored and recorded. No dietary restrictions were applied in this study, and the children were ensured with sufficient nutrition intake to maintain normal nutritional status. The children were required to avoid exercise for one day before screening and follow-up examinations.
Follow-up and outcomes
During the 26 weeks of intervention, the children were examined four times, i.e., at baseline and 4, 13, and 26 weeks of treatment.
The primary outcome was the height standard deviation score (Ht SDS) by the chronological age (CA) at the end of 26 weeks of treatment. △Ht SDSCA was defined as the Ht SDS at 26th week – height SDS at baseline. Height SDS = (height at the assessment – the average height of normal children of the same age and sex) / (standard deviation of height of normal children of the same age and sex).
The secondary outcome was the blood IGF-1 standard deviation score (IGF-1 SDS). Blood IGF-1 SDS = (actual IGF-1 level – median IGF-1 level of normal children of the same age and sex) / (the standard deviation of IGF-1level of normal children of the same age and sex).
The safety indicators included tolerability indicators, thyroid function, liver, and renal functions, blood glucose, glucose metabolism indicators, blood lipid, anti-hGH antibody positive, and general manifestations. The tolerability indicators were injection reactions of the local skin, allergy, limb pain, joint pain, gynecomastia, benign intracranial hypertension, intermittent claudication, slipped capital femoral epiphysis, scoliosis, peripheral edema, etc.
Statistical analysis
The continuous data were tested for normal distribution using the Kolmogorov–Smirnov test. Continuous data with a normal distribution were described as means ± standard deviations and tested using analysis of variance (ANOVA) and the least significant difference (LSD) post hoc test for intergroup comparison and paired t-test for intragroup comparison. Continuous data without normal distribution were described as median (IQR, interquartile range) and tested using the Kruskal–Wallis non-parametric test. Categorical data were described as n (%) and tested using the chi-square test or Fisher’s exact test. The significant (P < 0.05) variables in the univariable analyses were included in a multivariable analysis. Furthermore, the covariance analysis model was applied to assess the 6-month ΔHt SDS, with the dosage being the fixed effect and with the other baseline characteristics (such as IGF-1 SDS, sex, and baseline age) as covariates. The least-squares mean (LSM) estimates of 6-month ΔHt SDS in each dosage group were calculated. The differences in LSM among the different dosage groups with 95% CI were shown. The statistical analyses were two-sided, and P-values < 0.05 were considered statistically significant.