Abstract:Background:Differences in Multiple sclerosis (MS) disease-modifying therapy (DMT) prescribing patterns between different groups of neurologists have not been explored.Objective:To examine concentrations of prescribing patterns and to assess if MS-specialists use a broader range of DMTs relative to general neurologists.Methods:We conducted a cross-sectional study using administrative claims databases in Ontario, Canada to link neurologists to 2009 DMT prescription data. MS specialization was defined using both practice location and prescription patterns. Lorenz curves and Gini coefficients were constructed to examine prescribing patterns, separating neurologist characteristics dichotomously and separating Avonex from the other standard DMTs (Betaseron, Rebif and Copaxone). Gini coefficient 95% confidence intervals (CIs) were derived using jack-knife statistical techniques.Results:Prescriptions were highly concentrated with 12% of Ontario neurologists prescribing 80% of DMTs. There was a trend towards Avonex being more commonly prescribed relative to the other DMTs. When MS specialization was defined by DMT prescribing, high-volume prescribing neurologists showed a broader range of DMT prescribing (Gini 0.38-0.44) in comparison to low-volume prescribers (Gini 0.57-0.66).Conclusions:The majority of DMTs are prescribed by a small subset of neurologists. High-volume prescribing MS-specialists show more variability in DMT use while low-volume prescribers tend to individually focus on a narrower range of DMTs.