🟪 PASI (Psoriasis Area and Severity Index)
UseWhen to use: baseline and follow-up of plaque psoriasis when PASI is the agreed metric.
StrataHigher PASI = more severe. Trials often report PASI-75/90 responses.
LimitsWhen not to use: non-plaque phenotypes where PASI is a poor fit. · Pitfall: inconsistent area scoring between visits. · Add BSA and DLQI for treatment decisions.
SourceFredriksson T, Pettersson U. Dermatologica 1978 (PASI)
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
0–72 total.
When to use
When to use: baseline and follow-up of plaque psoriasis when PASI is the agreed metric.
How it works
Σ (E+I+D)×area×weight; weights head 0.1, upper 0.2, trunk 0.3, lower 0.4.
Key points
- 0–72 total.
- Region weights fixed.
- Next: BSA / DLQI / PGA.
References
- Fredriksson T, Pettersson U. Dermatologica 1978 (PASI)
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Head/neck area involvement | 30–49% (3) |
|---|---|
| Head: erythema 0–4 | 2 |
| Head: induration/thickness 0–4 | 2 |
| Head: desquamation/scale 0–4 | 2 |
| Upper limbs area involvement | 30–49% (3) |
| Upper limbs: erythema 0–4 | 2 |
| Upper limbs: induration 0–4 | 2 |
| Upper limbs: desquamation 0–4 | 2 |
| Trunk area involvement | 30–49% (3) |
| Trunk: erythema 0–4 | 2 |
| Trunk: induration 0–4 | 2 |
| Trunk: desquamation 0–4 | 2 |
| Lower limbs area involvement | 30–49% (3) |
| Lower limbs: erythema 0–4 | 2 |
| Lower limbs: induration 0–4 | 2 |
| Lower limbs: desquamation 0–4 | 2 |
→PASI18/72
- Head (×0.1)：1.8
- Upper (×0.2)：3.6
- Trunk (×0.3)：5.4
| Head/neck area involvement | 0% (0) |
|---|---|
| Head: erythema 0–4 | 0 |
| Head: induration/thickness 0–4 | 0 |
| Head: desquamation/scale 0–4 | 0 |
| Upper limbs area involvement | 0% (0) |
| Upper limbs: erythema 0–4 | 0 |
| Upper limbs: induration 0–4 | 0 |
| Upper limbs: desquamation 0–4 | 0 |
| Trunk area involvement | 0% (0) |
| Trunk: erythema 0–4 | 0 |
| Trunk: induration 0–4 | 0 |
| Trunk: desquamation 0–4 | 0 |
| Lower limbs area involvement | 0% (0) |
| Lower limbs: erythema 0–4 | 0 |
| Lower limbs: induration 0–4 | 0 |
| Lower limbs: desquamation 0–4 | 0 |
→PASI0/72
- Head (×0.1)：0.0
- Upper (×0.2)：0.0
- Trunk (×0.3)：0.0
Verification & sources · governance
FAQ
Frequently asked questions
- Does PASI (Psoriasis Area and Severity Index) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is PASI (Psoriasis Area and Severity Index) calculated in practice? Can you show a worked example?
- Inputs: Head/neck area involvement 30–49% (3), Head: erythema 0–4 2, Head: induration/thickness 0–4 2, Head: desquamation/scale 0–4 2, Upper limbs area involvement 30–49% (3), Upper limbs: erythema 0–4 2, Upper limbs: induration 0–4 2, Upper limbs: desquamation 0–4 2… → Result: PASI 18 /72（Head (×0.1): 1.8, Upper (×0.2): 3.6, Trunk (×0.3): 5.4） Inputs: Head/neck area involvement 0% (0), Head: erythema 0–4 0, Head: induration/thickness 0–4 0, Head: desquamation/scale 0–4 0, Upper limbs area involvement 0% (0), Upper limbs: erythema 0–4 0, Upper limbs: induration 0–4 0, Upper limbs: desquamation 0–4 0… → Result: PASI 0 /72（Head (×0.1): 0.0, Upper (×0.2): 0.0, Trunk (×0.3): 0.0）