ABSI: Validated prognostic score to predict survival in burn patients.
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Calculate Risk
Enter patient age, burn area, and inhalation status to estimate mortality probability.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use
Use ABSI in the initial triage of burn-injured patients to rapidly stratify mortality risk and guide decisions around burn center transfer, goals-of-care discussions, and resource allocation. It applies to patients of all ages with thermal injury requiring hospital-level evaluation.
Appropriate Patients
Adults and children with acute thermal (flame, scald, contact) burns
Burns requiring formal triage in ED or burn unit
Patients where inhalation injury status can be clinically assessed
Goals-of-care or family counseling in massive burns
When NOT to Use
Chemical or electrical burns (different pathophysiology; separate scoring)
Pediatric burns < 2 years (ABSI derivation cohort under-represents this group)
As a sole determinant of palliation — always supplement with clinical judgment
In isolation from burn surface area assessment (requires TBSA)
How it Works
Score Variables
ABSI uses five independently weighted variables derived from logistic regression analysis of burn patient outcomes. Each variable is assigned a point value reflecting its independent contribution to mortality risk.
Variable Weights
| Sex (female) | 1 point |
| Inhalation injury (present) | 1 point |
| Full-thickness burn (present) | 1 point |
| Age 0–20 yrs | 1 pt | 21–40: 2 | 41–60: 3 | 61–80: 4 | >80: 5 |
| % TBSA burned 0–9% | 1 pt | 10–19: 2 | 20–29: 3 | 30–39: 4 | 40–49: 5 | ≥50: 6 |
Score Range & Mortality Correlation
| 2–3 | Very low risk (survival probability ≥ 97%) |
| 4 | Low risk (survival probability ≈ 93%) |
| 5 | Moderate risk (survival probability ≈ 89%) |
| 6 | Moderate-high risk (survival probability ≈ 80%) |
| 7 | High risk (survival probability ≈ 67%) |
| 8 | Very high risk (survival probability ≈ 50%) |
| 9 | Critical risk (survival probability ≈ 25%) |
| 10–13 | Expected mortality > 90% |
Pathophysiological Basis
Female sex carries additional point due to observed worse outcomes in the original derivation cohort (hormonal and immunological differences in hypermetabolic response). Inhalation injury significantly compounds systemic inflammatory response. Full-thickness burns eliminate epidermal barrier function, increasing infection risk and fluid loss. Age is the dominant continuous variable — the elderly lose thermoregulatory and immune reserve disproportionately.
Clinical Pearls
Key Limitations
ABSI was derived in 1982 (n=776) — modern ICU care (early excision and grafting, specialized ventilator strategies) has improved survival beyond the original mortality curves; use scores as guidance, not absolute prediction.
The female sex penalty (1 point) has been questioned in contemporary cohorts; some centres apply the score without this variable for female patients.
Inhalation injury assessment is clinical (singed nasal hairs, carbonaceous sputum, stridor, hoarse voice) and carries interobserver variability.
ABSI does not account for burn wound depth other than the full-thickness (vs. partial-thickness) binary — it misses the spectrum of deep partial-thickness injuries.
The Revised Baux Score (Age + %TBSA + 17 if inhalation injury) is simpler and widely adopted for quick bedside estimation in parallel with ABSI.
Clinical Pearl
An ABSI ≥ 8 should trigger immediate discussion with the burn surgical team and ethics/palliative care given the >50% predicted mortality. A score of 11+ carries near-universal mortality even in high-resource burn centers.
Comparator Tools
Revised Baux Score — simpler, well validated in modern national burn repository data (n=39,888)
SCORTEN — preferred for TEN/SJS, not thermal burns
Baux Score (original, 1961) — age + %TBSA; no inhalation penalty, now superseded
Next Steps
Score-Based Action Framework
01
ABSI 2–5 (Low Risk): Standard burn unit care. Early excision and grafting for full-thickness areas. Fluid resuscitation per Parkland formula. Analgesia and wound care. Reassess daily.
02
ABSI 6–7 (Moderate-High Risk): Mandatory burn center involvement if not already present. ICU-level monitoring. Early dietitian and physiotherapy input. Discuss prognosis with family; establish goals of care framework.
03
ABSI 8–9 (Critical Risk): Convene burn surgery, ICU, palliative care, and ethics early. Establish explicit goals of care — aggressive resuscitation vs. comfort-focused care. Consider social work and spiritual support for family.
04
ABSI ≥ 10 (Near-Lethal): In most centers, expected mortality is >90%. Frame discussions around quality of remaining life and comfort-focused goals. Escalation to surgery requires explicit shared decision-making.
Transfer Criteria
American Burn Association criteria for burn center referral: >10% TBSA partial-thickness burn, any full-thickness burn, burns to face/hands/feet/genitalia/major joints, inhalation injury, chemical/electrical burns, or comorbidities complicating management — independent of ABSI score.
The Evidence
Derivation Study
The abbreviated burn severity index.
Tobiasen J et al. • Ann Emerg Med.. 1982;11(5):260-2. Derivation cohort n=776. ABSI demonstrated superior mortality prediction over clinical rules of thumb including original Baux score.
View SourceValidation Study
Prediction of burn mortality.
Tobiasen J et al. • Surg Gynecol Obstet.. 1982;154(5):711-4. Compared ABSI vs. Baux and modified Baux — ABSI showed superior specificity for predicting fatalities.
View SourceExternal Links
Origins & History
The Abbreviated Burn Severity Index was developed in 1982 by Dr. JoAnn Tobiasen, Dr. James M. Hiebert, and Dr. Richard F. Edlich at the University of Virginia Health System. It emerged from the recognition that clinical rules of thumb (including the original Baux score) failed to accurately predict fatalities — the most clinically consequential outcome. Using logistic regression on 776 burn patients, the team derived a weighted, multi-variable index that outperformed existing heuristics in mortality discrimination. The score remains a foundational tool in burn triage and has been widely cited in comparative burn scoring literature.
Last Comprehensive Review: 2026-07-17