Two scores, one question: who will get sick? Ranson needs 48 hours of data; BISAP needs one set of labs and a chest film. Both are now framed by the definition that actually decides severity, persistent organ failure.
| Ranson1974 · 11 criteria | BISAP2008 · 5 criteria | |
|---|---|---|
| When | 5 at admission, 6 more at 48 hours | Within 24 hours of presentation |
| Criteria | Admission: age >55, WBC >16,000, glucose >200 mg/dL, LDH >350 IU/L, AST >250 IU/L. 48 h: hematocrit fall >10 points, BUN rise >5 mg/dL, calcium <8 mg/dL, PaO₂ <60 mmHg, base deficit >4 mEq/L, fluid sequestration >6 L. | BUN >25 mg/dL · Impaired mental status · SIRS (≥2 criteria) · Age >60 · Pleural effusion on imaging. One point each. |
| Severe if | ≥3 | ≥3 |
| Mortality | Rises steeply with score in the original cohorts; the highest bands carried very high mortality in the 1970s | From under 1% at 0 to about 22% at 5 |
| Strength | Well studied; captures early fluid shifts | Bedside, early, similar discrimination to APACHE II |
| Weakness | Can't be completed until 48 h; criteria differ for gallstone pancreatitis | Single time point; misses later deterioration |
The rest of the chart is accurate: Ranson requires serial data and is delayed by design; BISAP trades completeness for speed; both perform similarly for early risk stratification.
Scores predict. The Revised Atlanta classification defines, and it defines severity by organ failure and its duration (modified Marshall score ≥2 in respiratory, cardiovascular, or renal systems).
This is why neither score settles the question at hour 24: the defining feature of severe disease, persistence, can't be known until hour 48.