Little is known about methylphenidate (MPH) use and mortality outcomes.

To investigate the association between MPH use and mortality among children with an attention-deficit hyperactivity disorder (ADHD) diagnosis.

This population-based cohort study analysed data from Taiwan's National Health Insurance Research Database (NHIRD). A total of 68 096 children and adolescents aged 4–17 years with an ADHD diagnosis and prescribed MPH between 2000 and 2010 were compared with 68 096 without an MPH prescription, matched on age, gender and year of first ADHD diagnosis. All participants were followed to death, migration, withdrawal from the National Health Insurance programme or 31 December 2013. MPH prescriptions were measured on a yearly basis during the study period, and the association between MPH use and mortality was analysed using a repeated-measures time-dependent Cox regression model. The outcome measures included all-cause, unnatural-cause (including suicide, accident and homicide) and natural-cause mortality, obtained from linkage to the National Mortality Register in Taiwan.

The MPH group had lower unadjusted all-cause, natural-, unnatural- and accident-cause mortality than the comparison group. After controlling for potential confounders, MPH use was associated with a significantly lower all-cause mortality (adjusted hazard ratio AHR = 0.81, 95% CI 0.67–0.98, P = 0.027), delayed use of MPH was associated with higher mortality (AHR = 1.05, 95% CI 1.01–1.09) and longer MPH use was associated with lower mortality (AHR = 0.83, 95% CI 0.70–0.98).

MPH use is associated with a reduced overall mortality in children with ADHD in this cohort study, but unmeasured confounding cannot be excluded absolutely.

Few studies have been conducted to investigate the influence of recombinant human erythropoietin (rhEPO) on the long-term prognosis of end-stage renal disease (ESRD).

A retrospective cohort study.

The largest regional hospital renowned for haemodialysis in northern Taiwan.

A total of 702 ESRD patients undergoing haemodialysis between 1993 and 2002 were evaluated.

The rate of overall use of rhEPO, vitamin D3 or Fe therapy was 62 %. The 10-year survival rate in patients with rhEPO supplementation was statistically more favourable than that in patients without rhEPO (hazard ratio (HR) = 0·38, 95 % CI 0·30, 0·47, P < 0·0001). Similar findings were noted for patients receiving vitamin D3 (HR = 0·36, 95 % CI 0·21, 0·64, P = 0.0004) and Fe (HR = 0·45, 95 % CI 0·33, 0·61, P < 0·0001). After adjusting for age, education and aetiology, the administration of rhEPO resulted in statistically significant improvements in long-term survival rate either with (HR = 0·30, 95 % CI 0·22, 0·42) or without (HR = 0·48, 95 % CI 0·38, 0·61) combined use of Fe or vitamin D3.

We demonstrated a reduction in long-term mortality related to supplementation therapy with rhEPO, vitamin D3 and Fe. The findings provide a justification for the administration of combined supplement therapy in patients undergoing haemodialysis.