Agitated Behavior Scale (ABS)

The ABS is a 14-item observational rating scale for quantifying agitation in patients with acquired brain injury. It captures agitation arising from neurological confusion — the disorganized, internally-driven hyperactivity seen in patients emerging from low consciousness — rather than ICU delirium (use the CAM-ICU for that). It's most useful during the agitated phase of recovery (roughly RLAS IV–V), when documenting agitation severity and tracking its trajectory over time matters for both treatment and communication with the team.

Target Population

Adults with acquired brain injury who are demonstrating agitated behavior during the acute or subacute recovery phase. Most relevant for patients at RLAS Level IV (confused/agitated) or early Level V. The ABS is not designed as a delirium screening tool; its target is the neurological confusional state following brain injury, which can overlap with but is clinically distinct from ICU delirium.

Administration

Score at the end of a therapy session or a period of structured observation (typically 30 minutes). Rate each item based on the highest frequency and intensity observed — not the average, not the last few minutes. Fourteen behaviors are rated:

Short attention span; impulsive behavior; unpredictable behavior; impatience/low frustration tolerance; aggression toward people or objects; pulling at tubes, catheters, or IV lines; explosive anger or emotional outbursts; throwing objects; excessive or incoherent talking; loud vocalization; repetitive body movements or excessive motor activity; restlessness or attempts to get out of bed; manipulative behavior; elopement attempts or unsafe self-removal from therapeutic situation.

Rating Scale

• 1 = Behavior absent

• 2 = Behavior present to a slight degree

• 3 = Behavior present to a moderate degree

• 4 = Behavior present to an extreme degree

Scores range from 14 to 56.

Scoring and Clinical Interpretation

• 14–21: Within normal limits

• 22–28: Mild agitation — the patient can typically participate in therapy; reduce task complexity, shorten session length, use a calm and consistent approach, minimize environmental stimulation

• 29–35: Moderate agitation — consider session timing carefully (after medication administration, optimal time of day per nursing); limit choices, keep the environment quiet, have a clear plan for redirecting or ending the session if behavior escalates

• 36–56: Severe agitation — the patient may not be safe to treat in a standard session; discuss timing and session approach with nursing and the medical team before proceeding

How to Use It Clinically

The ABS gives you a defensible, trackable number to communicate in documentation and team communication. "Patient scored 28 on the ABS, consistent with mild agitation; session modified to 20 minutes at bedside with reduced stimulation" is more informative than "patient was agitated and difficult to redirect."

Trending the score over sessions is more useful than any single data point. Consistent improvement from 32 → 26 → 19 over two weeks is clinically meaningful and communicates that the patient is responding to treatment and progressing through the recovery phase.

Strengths and Limitations

Strengths: free, validated in TBI, well-established in neurorehabilitation settings, straightforward to score at the bedside, creates a longitudinal record.

Limitations: requires direct observation during a session or defined period — not a chart review tool; interrater reliability improves with brief training; designed specifically for ABI-related agitation and should not be substituted for delirium screening in the general ICU population.