# CSHA Clinical Frailty Scale (Rockwood 2005)

CFS

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/cfs`
HTML: https://magentlab.com/docs/cfs
Markdown: https://magentlab.com/docs/cfs.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Return the Rockwood 2005 CSHA Clinical Frailty Scale 1-7 from a caller-assigned integer, with the published Box 1 description.

## When to use

When an agent already has a CSHA Clinical Frailty Scale 1-7 as in Rockwood 2005 Box 1 and must not invent the later 9-point CFS or CFS 2.0 labels.

## When not to use

- Not a medical device and not a diagnosis. magent does not examine the patient.
- Rockwood 2005 7-point CSHA Clinical Frailty Scale only. magent does not implement the later 9-point CFS (8 very severely frail, 9 terminally ill) or CFS 2.0 label changes.
- The caller assigns cfs 1-7. magent does not interview or examine the patient.

## Formula

```
CSHA Clinical Frailty Scale 1-7 as assigned by the caller (Rockwood 2005 Box 1); not the later 9-point CFS
```

## Citation

[A global clinical measure of fitness and frailty in elderly people](https://doi.org/10.1503/cmaj.050051)
Rockwood K, Song X, MacKnight C, Bergman H, Hogan DB, McDowell I, Mitnitski A
CMAJ. 2005;173(5):489-495
DOI: [10.1503/cmaj.050051](https://doi.org/10.1503/cmaj.050051)

## Worked example

### CFS 1 very fit

Given: `cfs=1`

1. cfs 1 → very fit; score 1; max 7


## Also searched as

- clinical frailty scale
- CSHA CFS
- Rockwood frailty
- Clinical Frailty Scale
- Rockwood CFS
- CSHA Clinical Frailty Scale
- frailty scale
- Rockwood 2005

## Parameters

- `cfs` (integer, required): Rockwood 2005 CSHA Clinical Frailty Scale 1-7 as assigned by the caller (1 very fit; 2 well; 3 well, with treated comorbid disease; 4 apparently vulnerable; 5 mildly frail; 6 moderately frail; 7 severely frail, completely dependent or terminally ill). magent does not examine the patient. The later 9-point CFS (8 very severely frail, 9 terminally ill) is not accepted.

## Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/cfs`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "cfs": "1"
    },
    {
      "cfs": "1"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/cfs

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/cfs",
  "items": [
    {
      "description": "Very fit — robust, active, energetic, well motivated and fit; these people commonly exercise regularly and are in the most fit group for their age",
      "components": [
        {
          "factor": "cfs",
          "points": 1,
          "present": true
        }
      ],
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Rockwood K, Song X, MacKnight C, Bergman H, Hogan DB, McDowell I, Mitnitski A",
        "doi": "10.1503/cmaj.050051",
        "id": "rockwood-2005",
        "pmid": "16129869",
        "source": "CMAJ. 2005;173(5):489-495",
        "title": "A global clinical measure of fitness and frailty in elderly people"
      },
      "formula": "cfs",
      "formula_expression": "CSHA Clinical Frailty Scale 1-7 as assigned by the caller (Rockwood 2005 Box 1); not the later 9-point CFS",
      "max_score": 7,
      "score": 1,
      "cfs": 1
    },
    {
      "description": "Very fit — robust, active, energetic, well motivated and fit; these people commonly exercise regularly and are in the most fit group for their age",
      "components": [
        {
          "factor": "cfs",
          "points": 1,
          "present": true
        }
      ],
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Rockwood K, Song X, MacKnight C, Bergman H, Hogan DB, McDowell I, Mitnitski A",
        "doi": "10.1503/cmaj.050051",
        "id": "rockwood-2005",
        "pmid": "16129869",
        "source": "CMAJ. 2005;173(5):489-495",
        "title": "A global clinical measure of fitness and frailty in elderly people"
      },
      "formula": "cfs",
      "formula_expression": "CSHA Clinical Frailty Scale 1-7 as assigned by the caller (Rockwood 2005 Box 1); not the later 9-point CFS",
      "max_score": 7,
      "score": 1,
      "cfs": 1
    }
  ]
}
```

## Response fields

- `formula` (string): cfs
- `formula_expression` (string): Published 1-7 CSHA 2005 rule
- `cfs` (integer): Caller-assigned CSHA Clinical Frailty Scale 1-7
- `score` (integer): Same as cfs
- `max_score` (integer): 7
- `description` (string): Rockwood 2005 Box 1 wording for that category
- `components` (array): CFS component
- `citation` (object): Rockwood 2005
- `disclaimer` (string): Not a medical device

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "description": "Very fit — robust, active, energetic, well motivated and fit; these people commonly exercise regularly and are in the most fit group for their age",
  "components": [
    {
      "factor": "cfs",
      "points": 1,
      "present": true
    }
  ],
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Rockwood K, Song X, MacKnight C, Bergman H, Hogan DB, McDowell I, Mitnitski A",
    "doi": "10.1503/cmaj.050051",
    "id": "rockwood-2005",
    "pmid": "16129869",
    "source": "CMAJ. 2005;173(5):489-495",
    "title": "A global clinical measure of fitness and frailty in elderly people"
  },
  "formula": "cfs",
  "formula_expression": "CSHA Clinical Frailty Scale 1-7 as assigned by the caller (Rockwood 2005 Box 1); not the later 9-point CFS",
  "max_score": 7,
  "score": 1,
  "cfs": 1
}
```

## Errors

- HTTP 400 `invalid_cfs`: cfs must be an integer from 1 to 7 (Rockwood 2005 CSHA Clinical Frailty Scale). Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

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- [NEWS2](https://magentlab.com/docs/news2) — Compute the RCP 2017 National Early Warning Score 2 from respiratory rate, SpO2 (Scale 1 or Scale 2), supplemental oxygen, temperature, systolic BP, heart rate, and caller-assigned ACVPU.
- [Braden Scale](https://magentlab.com/docs/braden) — Sum six caller-assigned Bergstrom 1987 Braden Scale subscale points and return at_risk when the total is ≤16.

## Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## Guarantees

- HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
- exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
- HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.