ADHD Clinical Outcome Scale – Self-Report (ACOS-Self)
A brief 15-item self-report measure of adult ADHD symptom severity.
Last reviewed: July 2026
- Full name
- ADHD Clinical Outcome Scale – Self-Report (ACOS-Self)
- Measures
- The ADHD Clinical Outcome Scale (ACOS) is a brief routine outcome measure for adult ADHD, developed by Adamis and colleagues (2024).
- Format
- 15 items · ~5 min · Self-report
- Score range
- 0 to 45
- Reliability
- The ACOS was validated in an adult ADHD clinic sample (Adamis et al., 2024, BJPsych Open).
- Population
- Adults aged 18 and over.
- Interpretation
- 0–14Minimal symptoms
- 15–29Moderate symptoms
- 30–45Significant symptoms
Scoring & Interpretation
In ClientForms each of the 15 items is scored 0 to 3 and summed to a total of 0 to 45, where higher scores indicate greater overall ADHD symptom severity and related difficulty. The total is mapped to three bands: Minimal (0 to 14), Moderate (15 to 29) and Significant (30 to 45). These grade severity to support outcome tracking; they are not diagnostic thresholds.
| Score Range | Severity | Clinical Action |
|---|---|---|
| 0–14 | Minimal symptoms | Low ADHD symptom burden on this measure — interpret in clinical context |
| 15–29 | Moderate symptoms | Moderate symptom burden — review alongside history, impairment and treatment |
| 30–45 | Significant symptoms | High symptom burden — consider comprehensive assessment or treatment review |
- The ACOS was validated in an adult ADHD clinic sample (Adamis et al., 2024, BJPsych Open).
- Published psychometric data for the self-report form are limited, and no validated clinical cut-off or test-retest coefficient has been established for the ACOS-Self; the severity bands above are descriptive thresholds for symptom burden, not diagnostic cut-offs.
- The score grades severity, and the treating psychologist owns the interpretation.
When to Use This vs Alternatives
| Instrument | Measures | Items | Reach for it when |
|---|---|---|---|
| ACOS This page | ADHD symptom severity (routine outcome) | 15 | The comprehensive option you are reading about |
| ASRS | ADHD symptom frequency (screen) | 6–18 | You need to screen for adult ADHD at intake rather than track change over time. The ASRS is a WHO screening tool that flags whether ADHD is likely; the ACOS is an outcome measure for monitoring symptom severity once ADHD is being managed. |
| ADHD-FIS | Functional impact (screening) | 18 | You want a screening read on functional impact specifically rather than overall symptom severity. The ADHD-FIS (an original 18-item checklist) focuses on how symptoms affect daily life; the ACOS gives a broader symptom-and-impact total. |
| AQ-10 | Autistic traits (screen) | 10 | Autism is part of the differential. The AQ-10 screens for autistic traits, which the ACOS does not assess; use it where an autism question sits alongside ADHD. |
ADHD symptom severity (routine outcome) · 15 items
ADHD symptom frequency (screen) · 6–18 items
You need to screen for adult ADHD at intake rather than track change over time. The ASRS is a WHO screening tool that flags whether ADHD is likely; the ACOS is an outcome measure for monitoring symptom severity once ADHD is being managed.
Functional impact (screening) · 18 items
You want a screening read on functional impact specifically rather than overall symptom severity. The ADHD-FIS (an original 18-item checklist) focuses on how symptoms affect daily life; the ACOS gives a broader symptom-and-impact total.
Autistic traits (screen) · 10 items
Autism is part of the differential. The AQ-10 screens for autistic traits, which the ACOS does not assess; use it where an autism question sits alongside ADHD.
See It in Action
Sample: a completed ACOS, scored and interpreted.
How a completed ACOS scores and interprets:
Moderate ADHD symptom load.
On ClientForms the total and its severity band are scored for you and ready to read or export as a PDF.
See the dashboard view
Synthetic sample for illustration — not a real patient.
What It Measures
It has a clinician-rated form and a self-report form (ACOS-Self). Its 15 items cover the core symptoms of ADHD (attention and organisation, hyperactivity and impulsivity) together with common co-occurring difficulties and their impact on everyday functioning. It gives an overall severity score designed to track change over a course of care, not to establish a diagnosis.
When to Use the ACOS
Use the ACOS to monitor adult ADHD symptom severity over time, for example at baseline and again at review to see whether treatment is reducing symptoms and their day-to-day impact. It is an outcome measure, not a screening or diagnostic instrument: interpret the total in the context of a full assessment. The self-report form (ACOS-Self) is completed by the patient, and a clinician-rated form is also available.
Who It's For
Adults aged 18 and over. Self-report (the patient completes the ACOS-Self), with a clinician-rated form also available. The scale was validated in an adult ADHD clinic sample (Adamis et al., 2024, n=148). As a brief outcome measure it complements, rather than replaces, structured diagnostic assessment and clinical interview.
Frequently Asked Questions
What is the ACOS (ADHD Clinical Outcome Scale)?
The ACOS is a brief 15-item routine outcome measure of adult ADHD symptom severity, developed by Adamis and colleagues (2024). It has clinician-rated and self-report (ACOS-Self) forms and covers core ADHD symptoms together with common co-occurring difficulties. It is designed to track change, not to diagnose.
How is the ACOS scored?
In ClientForms the 15 items are each scored 0 to 3 and summed to a total of 0 to 45. The total maps to three severity bands: Minimal (0 to 14), Moderate (15 to 29) and Significant (30 to 45). Higher scores indicate greater symptom severity; the bands grade severity rather than establish a diagnosis.
Is the ACOS a diagnostic test for ADHD?
No. The ACOS is an outcome and severity measure, not a diagnostic instrument. ADHD diagnosis relies on a structured assessment of DSM-5 criteria, developmental history and functional impairment; the ACOS helps monitor symptoms once that assessment is done, and the clinician owns the interpretation.
Where can I get the ACOS, and is it free to use?
The ACOS was published open access (Adamis et al., 2024, BJPsych Open) and is free to use with attribution for clinical practice and research. On ClientForms you send the ACOS-Self to a patient, who completes it on their phone, and the total, its severity band and the item responses come back scored for you, ready to read or export.
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