Objective To assess the global situation of off-label drug use in outpatient children.Methods A search was conducted in PubMed, EMbase, CBM, CNKI and VIP for collecting studies on off-label drug use in outpatient children aged 0 to 18 years, and the publication language was limited to English and Chinese. The quality assessment was based on Crombie Criteria for cross-sectional studies, and the descriptive analysis was performed to analyze the incidence of off-label drug use at all levels of medical institutes and different age groups, the common types of off-label used drugs, and the constitution ratio of off-label use drugs. Results A total of 20 cross-sectional studies were included, involving 1 933 760 children and 5 262 573 prescriptions. The results of descriptive analysis showed: a) The incidence of off-label drug use in outpatient children in primary care and tertiary care institutes were 19.5% (IQR 13.5%, 24.5%) and 26.0% (IQR 24.0%, 35.0%), respectively; b) The primary studies reported that neonate, infant and adolescent had the highest incidence of off-label drug use, while the other children had the lowest incidence; c) Drugs for respiratory system, anti-infection, sensory organs, and dermatosis were listed as the top 5 frequently used off-label drugs by more than half of the studies; d) The studies with issue of “lack of instruction for children” showed it was exactly the type with highest incidence of off-label use, while other studies without that issue showed the highest incidence was over aged off-label use. Conclusion a) Off-label drug use is common in outpatient children. The incidence of off-label drug use may be higher in tertiary care institutes than primary care institutes, and it is higher in neonate, infant and adolescent rather than other age groups of children; b) Incidence of off-label use may be higher in inpatient children than outpatient ones; c) Drugs for respiratory system, anti-infection, sensory organs, and dermatosis were most common types of off-label use; and d) Off-label use due to both “lack of instruction for children” and “over aged use” is more common. So it suggests that further studies trials should focus on fields in which clinical trials of drugs are totally absent.
