RESUMEN
AIMS: Animal studies suggest that methylphenidate treatment for around 3 months may lead to less mineralized and weaker appendicular bones. A systematic review was conducted to summarize the evidence from observational studies, and a self-controlled case series study was used to compare the risk before and after treatment initiation. METHODS: Literature search was conducted using PubMed, Embase and the Cochrane Library to identify observational studies on methylphenidate and fractures. We also conducted a self-controlled case series study with individuals aged 5-24 years who received methylphenidate treatment and experienced fractures from 2001 to 2020 in Hong Kong. Incidence rate ratios and 95% confidence intervals were calculated by comparing the incidence rate in the methylphenidate-exposed period compared with nonexposed period. RESULTS: Six cohort studies and 2 case-control studies were included in the systematic review. For all-cause fractures, studies found a 39-74% lower risk in treated-attention deficit hyperactivity disorder (ADHD) group compared with untreated ADHD but no difference between stimulants and nonstimulants. Differences between sexes and treatment duration were also found-significant results were shown in males and those with longer treatment duration. Among 43 841 individuals with ADHD medication before the year 2020, 2023 were included in the self-controlled case series analysis. The risks of fractures were lower by 32-41% in different treatment periods when compared with 6 months before treatment initiation. CONCLUSION: Methylphenidate treatment may lower the risk of all-cause fractures from both study designs; however, further evidence is needed about the treatment duration and sex effect. Conclusions on stress fractures are not yet established, and further research is required.