In studies of adult patients with attention deficit hyperactivity disorder (ADHD) atomoxetine (ATX) has demonstrated substantial improvements in ADHD symptomatology using Conners’ Adult ADHD Rating Scales (CAARS). The pattern suggests incremental response over time with no clear plateau of response.

To identify patterns of response to ATX in adult ADHD patients and to describe those trajectories over time

To determine if patients have distinct response trajectories using CAARS in two populations, short term (12 weeks) and long term (24 weeks) treatment data.

Data from 2502 ATX patients, who had an investigator-rated CAARS total score at ≥ short or long term time point, The numbers of trajectory clusters for short term (n=2502) and long term (n=1139) data were identified using hierarchical clustering methods. Linear mixed modelling was used to describe those different trajectories over time.

Using CAARS total, 4 trajectory clusters were identified in short term treated patients and 5 in long term. Three out of 4 short term trajectory clusters (representing 84% of patients) and 4 out 5 long term (representing 96%) showed more successful trajectories. In general clusters with less improvement were those with the worst baseline CAARS and minimal initial improvement. Distinct trajectory patterns of response were found that were incremental over time in all clusters.

Adult ADHD patients receiving atomoxetine have individual trajectories of response that can be divided into 4 short term trajectories and 5 long term trajectories. Further analysis is ongoing to describe these cohorts.