# Pneumonia risk score (Lipsett)

PRS

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

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

## What it computes

Compute the Lipsett 2022 Pneumonia Risk Score logistic probability of radiographic pneumonia in children 3 months to 18 years, and the supplement integer score 1–6, from age, triage oxygen saturation, fever, rales, and wheeze.

## When to use

When an agent already has caller-assigned pediatric age, triage saturation, fever, rales, and wheeze for a child in whom CXR was considered for suspected pneumonia and needs the published Lipsett 2022 probability and score, not a pneumonia diagnosis and not a CXR or antibiotic order.

## When not to use

- Not a medical device. magent does not diagnose pneumonia and does not order a chest radiograph or antibiotics.
- Not CURB-65. CURB-65 is an adult severity score. This is the Lipsett 2022 pediatric radiographic-pneumonia model only.
- Derived and validated in children whose clinicians already obtained a CXR for suspected pneumonia. Broad use in all respiratory illness may overestimate probability.
- Age, saturation, fever, rales, and wheeze are caller-assigned. magent does not auscultate or take a saturation.
- Score 1–6 is the published SDC mapping from the logistic probability. magent does not invent additional named risk bands.

## Formula

```
logit = 18.05624 + 0.098308*age_years + 1.144985*fever + (-0.21636)*spo2_percent + 0.407494*rales + (-0.907087)*wheeze (Lipsett 2022 SDC INF/E552; flags 1 if true else 0); probability_percent = 100 * exp(logit) / (1 + exp(logit)) from the unrounded logit, 2 decimals; score 1 if p < 0.05, 2 if p < 0.11, 3 if p < 0.21, 4 if p < 0.51, 5 if p < 0.75, else 6 (SDC wrote >=0.76 after <0.75; magent closes that hole at 0.75)
```

## Citation

[Development of the Novel Pneumonia Risk Score to Predict Radiographic Pneumonia in Children](https://doi.org/10.1097/INF.0000000000003361)
Lipsett SC, Hirsch AW, Monuteaux MC, Bachur RG, Neuman MI
Pediatr Infect Dis J. 2022;41(1):24-30
DOI: [10.1097/INF.0000000000003361](https://doi.org/10.1097/INF.0000000000003361)

## Worked example

### Age 2 years, no fever, SpO2 99, no rales, no wheeze

Given: `age_years=2, fever=false, rales=false, spo2_percent=99, wheeze=false`

1. logit = 18.05624 + 0.098308×2 + (−0.21636)×99 = −3.1668
2. probability_percent = 100 × exp(logit) / (1 + exp(logit)) = 4.04
3. score 1 (predicted probability < 0.05)


### Age 18 years, fever, SpO2 88, rales, no wheeze

Given: `age_years=18, fever=true, rales=true, spo2_percent=88, wheeze=false`

1. logit = 18.05624 + 0.098308×18 + 1.144985 + (−0.21636)×88 + 0.407494 = 2.3386
2. probability_percent = 100 × exp(logit) / (1 + exp(logit)) = 91.20
3. score 6 (predicted probability ≥ 0.75)


## Also searched as

- pneumonia risk score
- Lipsett PRS
- novel pneumonia risk score
- pediatric radiographic pneumonia
- pediatric CXR pneumonia score
- Lipsett 2022 pneumonia

## Parameters

- `age_years` (number, required): Age in years, continuous (0.25-18). Lipsett 2022 enrolled children 3 months to 18 years. Not adult Params.age.
- `spo2_percent` (number, required): Triage / first oxygen saturation percent (50-100). Caller-assigned. magent does not measure saturation.
- `fever` (boolean, required): Fever at home or in the ED (Lipsett 2022 SDC: >38°C). true or false. Caller-assigned.
- `rales` (boolean, required): Rales / crackles on exam as assigned by the caller (Lipsett 2022). true or false. magent does not auscultate.
- `wheeze` (boolean, required): Wheeze on exam as assigned by the caller (Lipsett 2022). true or false. magent does not auscultate.

## 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/prs`
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": [
    {
      "age_years": "2",
      "fever": "false",
      "rales": "false",
      "spo2_percent": "99",
      "wheeze": "false"
    },
    {
      "age_years": "2",
      "fever": "false",
      "rales": "false",
      "spo2_percent": "99",
      "wheeze": "false"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/prs",
  "items": [
    {
      "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": "Lipsett SC, Hirsch AW, Monuteaux MC, Bachur RG, Neuman MI",
        "doi": "10.1097/INF.0000000000003361",
        "id": "lipsett-2022",
        "pmid": "34694254",
        "source": "Pediatr Infect Dis J. 2022;41(1):24-30",
        "title": "Development of the Novel Pneumonia Risk Score to Predict Radiographic Pneumonia in Children"
      },
      "formula": "prs",
      "formula_expression": "logit = 18.05624 + 0.098308*age_years + 1.144985*fever + (-0.21636)*spo2_percent + 0.407494*rales + (-0.907087)*wheeze (Lipsett 2022 SDC INF/E552; flags 1 if true else 0); probability_percent = 100 * exp(logit) / (1 + exp(logit)) from the unrounded logit, 2 decimals; score 1 if p < 0.05, 2 if p < 0.11, 3 if p < 0.21, 4 if p < 0.51, 5 if p < 0.75, else 6 (SDC wrote >=0.76 after <0.75; magent closes that hole at 0.75)",
      "age_years": 2.0,
      "max_score": 6,
      "score": 1,
      "logit": -3.1668,
      "spo2_percent": 99.0,
      "fever": false,
      "wheeze": false,
      "probability_percent": 4.04,
      "rales": false
    },
    {
      "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": "Lipsett SC, Hirsch AW, Monuteaux MC, Bachur RG, Neuman MI",
        "doi": "10.1097/INF.0000000000003361",
        "id": "lipsett-2022",
        "pmid": "34694254",
        "source": "Pediatr Infect Dis J. 2022;41(1):24-30",
        "title": "Development of the Novel Pneumonia Risk Score to Predict Radiographic Pneumonia in Children"
      },
      "formula": "prs",
      "formula_expression": "logit = 18.05624 + 0.098308*age_years + 1.144985*fever + (-0.21636)*spo2_percent + 0.407494*rales + (-0.907087)*wheeze (Lipsett 2022 SDC INF/E552; flags 1 if true else 0); probability_percent = 100 * exp(logit) / (1 + exp(logit)) from the unrounded logit, 2 decimals; score 1 if p < 0.05, 2 if p < 0.11, 3 if p < 0.21, 4 if p < 0.51, 5 if p < 0.75, else 6 (SDC wrote >=0.76 after <0.75; magent closes that hole at 0.75)",
      "age_years": 2.0,
      "max_score": 6,
      "score": 1,
      "logit": -3.1668,
      "spo2_percent": 99.0,
      "fever": false,
      "wheeze": false,
      "probability_percent": 4.04,
      "rales": false
    }
  ]
}
```

## Response fields

- `formula` (string): prs
- `formula_expression` (string): Exact expression used
- `age_years` (number): Input age in years
- `spo2_percent` (number): Input triage oxygen saturation percent
- `fever` (boolean): Fever at home or in the ED
- `rales` (boolean): Caller-assigned rales / crackles
- `wheeze` (boolean): Caller-assigned wheeze
- `logit` (number): Lipsett 2022 SDC logit, 4 decimal places
- `probability_percent` (number): Predicted probability of radiographic pneumonia as a percent from the unrounded logit, 2 decimals. Not a diagnosis.
- `score` (integer): Integer Pneumonia Risk Score 1-6 from the SDC probability bins. Not a CXR or antibiotic order.
- `max_score` (integer): 6
- `citation` (object): Lipsett et al. 2022 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "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": "Lipsett SC, Hirsch AW, Monuteaux MC, Bachur RG, Neuman MI",
    "doi": "10.1097/INF.0000000000003361",
    "id": "lipsett-2022",
    "pmid": "34694254",
    "source": "Pediatr Infect Dis J. 2022;41(1):24-30",
    "title": "Development of the Novel Pneumonia Risk Score to Predict Radiographic Pneumonia in Children"
  },
  "formula": "prs",
  "formula_expression": "logit = 18.05624 + 0.098308*age_years + 1.144985*fever + (-0.21636)*spo2_percent + 0.407494*rales + (-0.907087)*wheeze (Lipsett 2022 SDC INF/E552; flags 1 if true else 0); probability_percent = 100 * exp(logit) / (1 + exp(logit)) from the unrounded logit, 2 decimals; score 1 if p < 0.05, 2 if p < 0.11, 3 if p < 0.21, 4 if p < 0.51, 5 if p < 0.75, else 6 (SDC wrote >=0.76 after <0.75; magent closes that hole at 0.75)",
  "age_years": 2.0,
  "max_score": 6,
  "score": 1,
  "logit": -3.1668,
  "spo2_percent": 99.0,
  "fever": false,
  "wheeze": false,
  "probability_percent": 4.04,
  "rales": false
}
```

## Errors

- HTTP 400 `invalid_prs`: PRS inputs must match Lipsett 2022 age, triage oxygen saturation, fever, rales, and wheeze from that paper. Returned before settlement; you are not charged.
- HTTP 400 `invalid_spo2`: spo2_percent must be a number from 50 to 100. Returned before settlement; you are not charged.
- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false 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

## Related tools

- [Pediatric SIRS](https://magentlab.com/docs/pediatric-sirs) — Apply Goldstein 2005 pediatric SIRS age-group heart-rate, respiratory-rate, leukocyte, and core-temperature criteria, then the paper's sepsis, severe-sepsis, and septic-shock definitions from caller-assigned infection and organ-dysfunction flags.
- [Centor and McIsaac scores](https://magentlab.com/docs/centor) — Compute the Centor score or the McIsaac age-modified score from four caller-assigned pharyngitis findings. The edition is required.

## 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.