Establishing clinically important differences in adults with attention deficit/hyperactivity disorder.

Area of Science:

• Psychiatry
• Clinical Psychology
• Neuroscience

Background:

• The Adult ADHD Self-Report Scale (ASRS) is a key patient-reported outcome measure (PROM) for adult ADHD clinical trials.
• Clinically important differences (CIDs) for the ASRS are not well-defined, hindering interpretation of treatment effects.
• Existing literature lacks established CID values for the ASRS in adult ADHD populations.

Purpose of the Study:

• To review the reporting of CIDs for the ASRS in randomized controlled trials (RCTs) for adult ADHD.
• To establish specific CID values for the ASRS in adults with ADHD.
• To provide benchmarks for interpreting treatment response and informing future clinical trial designs.

Main Methods:

• A literature search identified RCTs reporting ASRS CID values.
• Secondary analysis of an RCT involving 56 adults with ADHD using the ASRS as the PROM.
• An anchor-based approach with the Clinical Global Impression-Improvement scale was employed.
• General linear mixed-effects modeling determined categorical CID thresholds based on patient-defined improvement.

Main Results:

• No identified studies reported ASRS CID values for adult ADHD.
• A reduction of ~13.39 points in ASRS total score signifies clinically meaningful within-group improvement (CID_within-group).
• A between-group difference of ~6.13 points in ASRS total score indicates a minimal clinically meaningful difference (CID_{between-group}).

Conclusions:

• This study provides the first adult ADHD-specific CID estimates for the ASRS.
• These CID values serve as practical benchmarks for evaluating treatment efficacy.
• The findings will aid in interpreting treatment response and optimizing power calculations for future clinical trials.