# ASDAS-CRP Calculator (van der Heijde 2009)

> ASDAS-CRP Calculator (van der Heijde 2009) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Computes the Ankylosing Spondylitis Disease Activity Score using CRP (ASDAS-CRP) from five caller-supplied clinical inputs using the van der Heijde 2009 formula.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/asdas_crp
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/asdas-crp-calculator-van-der-heijde-2009-f1e34714
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7s7HN1EtUo2IALksxkKFM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability asdas-crp-calculator-van-der-heijde-2009-f1e34714
```

Example prompt: Calculate the ASDAS-CRP score for a patient with back pain 6/10, morning stiffness duration 4/10, patient global 7/10, peripheral pain/swelling 2/10, and a CRP of 18 mg/L.

## When to prefer this

Choose this endpoint when you need the ASAS-preferred CRP-based ASDAS formula (van der Heijde 2009) specifically — not ASDAS-ESR, not the BASDAI total, and not Machado 2011 cut-point categorization. Ideal when CRP is available in mg/L and you want a reproducible, formula-exact computation without relying on local code.

## Known failure modes

- Missing required query parameters (back_pain, morning_stiffness_duration, patient_global, peripheral_pain_swelling, crp_mg_l) returns an error
- CRP value outside 0–500 mg/L range is clamped by magent
- Non-numeric values for any parameter cause a validation error
- Payment failure (x402) if USDC balance is insufficient

## How this service works

van der Heijde 2009 ASDAS-CRP: 0.12*back pain + 0.06*morning stiffness duration + 0.11*patient global + 0.07*peripheral pain/swelling + 0.58*ln(CRP+1). BASDAI 0-10 items and CRP in mg/L. ASAS selected the CRP version as preferred. magent does not examine the patient or assay CRP. Not ASDAS-ESR. Not BASDAI total. Does not apply Machado 2011 1.3/2.1/3.5 activity cuts. Not a diagnosis or biologic order.

## Output

Returns a numeric ASDAS-CRP value computed as 0.12×back_pain + 0.06×morning_stiffness_duration + 0.11×patient_global + 0.07×peripheral_pain_swelling + 0.58×ln(CRP+1), representing overall axial spondyloarthritis disease activity. Does not apply Machado 2011 activity category cut-points or produce a diagnosis.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "back_pain",
      "morning_stiffness_duration",
      "patient_global",
      "peripheral_pain_swelling",
      "crp_mg_l"
     ],
     "properties": {
      "crp_mg_l": {
       "type": "number",
       "description": "Caller-assigned C-reactive protein in mg/L (van der Heijde 2009; not mg/dL). Number 0-500 is a magent clamp. The 2009 papers do not floor CRP at 2 mg/L. magent does not assay CRP."
      },
      "back_pain": {
       "type": "number",
       "description": "Caller-assigned total back pain on a 0-10 VAS or NRS (van der Heijde 2009; BASDAI question 2, neck/back/hip pain). Number 0-10. magent does not examine the patient."
      },
      "patient_global": {
       "type": "number",
       "description": "Caller-assigned patient global assessment of disease activity on a 0-10 VAS or NRS (van der Heijde 2009). Number 0-10. magent does not examine the patient."
      },
      "peripheral_pain_swelling": {
       "type": "number",
       "description": "Caller-assigned peripheral pain/swelling on a 0-10 VAS or NRS (van der Heijde 2009; BASDAI question 3, joints other than neck/back/hips). Number 0-10. magent does not examine the patient."
      },
      "morning_stiffness_duration": {
       "type": "number",
       "description": "Caller-assigned duration of morning stiffness on a 0-10 VAS or NRS (van der Heijde 2009; BASDAI question 6). Number 0-10, not hours. magent does not examine the patient."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/asdas-crp-calculator-van-der-heijde-2009-f1e34714/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)