Eleven studies (2,489 patients, range 40 to 926) were included in the review. None of the studies was a randomised controlled trial. Duration of follow-up ranged from 35 to 89 months, where reported. Two studies were rated quality score 2, five studies were rated 3, two studies were rated 5, one rated 6 and one rated 7.
Adolescents and young adult patients given paediatric-inspired regimens had a statistically significant reduction in all-cause mortality at the end of the study period (RR 0.59, 95% CI 0.52 to 0.66; 10 studies; Ι²=24%) and at three years (RR 0.58, 95% CI 0.51 to 0.67; eight studies) compared with patients given the conventional adult regimes. The absolute risk reduction for all-cause mortality at three years was 0.20 and the number needed to treat to prevent one death with paediatric-inspired regimens was 5 (95% CI 4 to 7).
Subgroup analysis could not be performed for the patients older than 20 years as the available studies did not report outcomes separately for patients older than 20 years of age. Sensitivity analyses for higher methodological quality and well-controlled studies showed similar results.
Complete remission rate after induction chemotherapy was superior in the paediatric-inspired regimens arm (RR 1.05, 95% CI 1.01 to 1.10; seven studies; Ι²=55%) at three years. Patients in the paediatric-inspired regimens had higher event-free survival rates compared with the conventional adult regimes (RR 1.66, 95% CI 1.39 to 1.99; nine studies; Ι²=61%). Sensitivity analysis of well-controlled studies for complete remission rate and event free-survival also showed similar results.
There was a statistically significant reduction in relapse rate in the paediatric-inspired regimens compared with the conventional-adult regimes (RR 0.51, 95% CI 0.39 to 0.66; eight studies; Ι²=54%). No statistically significant difference was found in the rate of non-relapse mortality between the two groups (RR 0.53, 95% CI 0.19 to 1.48; four studies; Ι²=56%).