# CDAI Calculator for Rheumatoid Arthritis (Aletaha 2005)

> CDAI Calculator for Rheumatoid Arthritis (Aletaha 2005) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-13).

Computes the Clinical Disease Activity Index (CDAI) for rheumatoid arthritis by summing SJC28, TJC28, patient global assessment, and evaluator global assessment (no CRP required).

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/cdai_ra
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cdai-calculator-for-rheumatoid-arthritis-aletaha-2005-37f35a0d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5BzOgEsX36zs7-3onsv4G

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 cdai-calculator-for-rheumatoid-arthritis-aletaha-2005-37f35a0d
```

Example prompt: Calculate the CDAI score for my RA patient who has 6 swollen joints and 9 tender joints on the 28-joint count, a patient global assessment of 6.5 cm and an evaluator global of 4.0 cm.

## When to prefer this

Choose this endpoint when you need to compute the Aletaha 2005 CDAI for rheumatoid arthritis specifically — it is the only validated RA composite score that requires no laboratory values (no CRP or ESR). Prefer this over SDAI when lab results are unavailable or when using the CDAI-specific validation from Arthritis Res Ther 2005. Do not use for Crohn's disease activity (Harvey-Bradshaw/CDAI-IBD) or for diagnosing RA.

## Known failure modes

- Missing required parameters (sjc28, tjc28, pga, ega) returns an error
- SJC28 or TJC28 outside integer range 0–28 may return a validation error
- PGA or EGA outside 0–10 range may return a validation error
- Non-integer values for sjc28 or tjc28 may be rejected
- Payment failure (x402) if USDC balance is insufficient

## How this service works

Aletaha 2005 Clinical Disease Activity Index (CDAI) for rheumatoid arthritis: SJC28 + TJC28 + patient global (0–10 cm) + evaluator global (0–10 cm). No CRP. Half points allowed; the sum is not integer-rounded. magent does not count joints. Arthritis Res Ther 2005 (ar1740) validates the sum and does not publish activity-state cutoffs. Not SDAI. Not Crohn's CDAI. Not a rheumatoid arthritis diagnosis.

## Output

Returns a continuous numeric CDAI score (sum of SJC28 + TJC28 + PGA + EGA), which can include half-point values and is not integer-rounded. The score ranges from 0 to 76. No activity-state cutoffs are applied by this endpoint; interpretation of remission/low/moderate/high activity is left to the caller.

## 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": [
      "sjc28",
      "tjc28",
      "pga",
      "ega"
     ],
     "properties": {
      "ega": {
       "type": "number",
       "description": "Caller-assigned evaluator global assessment on a 0-10 cm VAS (Aletaha 2005 CDAI). Number 0-10. magent does not examine the patient."
      },
      "pga": {
       "type": "number",
       "description": "Caller-assigned patient global assessment on a 0-10 cm VAS (Aletaha 2005 CDAI). Number 0-10. magent does not examine the patient."
      },
      "sjc28": {
       "type": "integer",
       "description": "Caller-assigned swollen joint count on the 28-joint set (Aletaha 2005 CDAI). Integer 0-28. magent does not count joints."
      },
      "tjc28": {
       "type": "integer",
       "description": "Caller-assigned tender joint count on the 28-joint set (Aletaha 2005 CDAI). Integer 0-28. magent does not count joints."
      }
     }
    }
   },
   "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/cdai-calculator-for-rheumatoid-arthritis-aletaha-2005-37f35a0d/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)