The incidence of methylphenidate use by Canadian children: What is the impact of socioeconomic status and urban or rural residence?

Objective: To examine socioeconomic, demographic, and behavioural factors that influence the incidence of methylphenidate use among children aged 4 to 13 years. Method: A total of 11 3 16 children, aged 2 through I I years, from Cycle I (1994-95) of the National Longitudinal Survey of Children and Youth were followed up 2 years later in Cycle 2 (1996-97). The outcome measure was methylphenidate use in Cycle 2. Individual-level explanatory variables included sex, age, socioeconomic status (SES), mother's age at birth of child, lone-parent family status, parental working status, and hyperactivity-impulsivity and inattention probabilities. Area-level explanatory variables included income and rural or urban residence. We used hierarchical linear modelling to examine individual- and area-level factors that predicted methylphenidate use. Results: The strongest predictors of methylphenidate use were behavioural: children with high hyperactive-impulsive and (or) inattention behaviours in 1994, compared with children low on these behaviours, were 4.5 to 6 times more likely to use methylphenidate 2 years later. SES remained a significant predictor of the incidence of methylphenidate use, even when other significant predictors were held constant, with lower SES being associated with higher use. Area-level income also predicted methylphenidate use. Conclusion: Even when children with similar behavioural symptoms and demographic characteristics were compared, socioeconomic factors had a significant impact on incidence of methylphenidate use.