Improved adherence and growth outcomes with jet-delivered growth hormone

Background We previously reported improved persistence and adherence to daily recombinant growth hormone (rGH) in children using jet transjection delivery compared to using needle-based devices. This study examines the relationship between improved adherence and medium-term growth outcomes in children receiving jet-delivered rGH (JrGH) at a single centre. Methods This was a retrospective longitudinal follow-up study of children (<16 years) treated with daily JrGH (somatropin; Ferring Pharmaceuticals) in the form of Zomacton® with the Zomajet® device. Delivery schedules of home distribution services were utilised to calculate adherence, quantified as the proportion of days covered (PDC) index (PDC > 0.8 adherent, PDC ≤ 0.8 less adherent). Demography, patient history, height standard deviation scores (HTSDS) and difference from mid-parental height SDS (MPHSDS - HTSDS) were extracted from hospital records for up to 3 years of treatment. Results Of 75 patients eligible for JrGH, 52 had PDC treatment and height data for at least 1 year and 22 for 3 years. A greater proportion of patients were classified as adherent in both 1- and 3-year treated cohorts (adherent 30 [57.7%] and 14 [63.6%], less adherent 22 [42.3%] and 8 [36.4%]). After 1 year of JrGH treatment, HTSDS was not significantly different in either adherence group. After 3 years, only adherent patients demonstrated sustained year-on-year increments in HTSDS and significant improvement in target HTSDS positions (by 1.32 SDS) compared to baseline (p = 0.0008). MPHSDS - HTSDS showed a similar significant improvement at 3 years in adherent patients only (p = 0.0043). Conclusions Patients adherent to JrGH demonstrate significant growth improvement compared to baseline over 3 years.