VACO Index 30-day mortality

VACO Index

Compute the King 2020 VACO Index 30-day all-cause mortality probability from age, sex, a caller-assigned unadjusted Charlson comorbidity index, and history of myocardial infarction or peripheral vascular disease using Supplement S3 coefficients.

LIVE $0.005 USDC GET /api/calc/vaco

Markdown: /docs/vaco.md · Canonical: https://magentlab.com/docs/vaco

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

What it computes

When to use

When an agent already has age, sex, a caller-assigned unadjusted Charlson score, and whether MI or PVD is present, and needs the published King 2020 S3 logistic 30-day probability, not VACS Index 1.0, VACS 2.0, 4C, or PRIEST.

When not to use

Not a medical device and not a diagnosis. Not a treatment, triage, isolation, or disposition order.
magent does not assign Charlson diagnoses. CCI is caller-assigned from administrative codes as in King 2020; this tool does not run ICD-10 mapping.
Age 85 years or older uses the published combined age–CCI term; the numeric CCI does not change the linear predictor.
Not VACS Index 1.0 and not VACS 2.0. King 2020 did not retain race or ethnicity in the final index; magent does not add either.
Derivation used early-pandemic VA testing. King 2020 publishes no later-wave recalibration in S3.

Formula

lp = intercept + age_term + sex_term + cci_term + mi_pvd_term; probability = exp(lp)/(1+exp(lp)); King 2020 S1 File (PLOS S3); intercept -4.216058062; female 0; male 0.322291449; no MI/PVD 0; MI or PVD 0.267265312; age 20-50 (ages 20-49) -2.228678713, 50-54 0, 55-59 0.400599289, 60-64 0.941322019, 65-69 1.295007128, 70-74 1.629533438, 75-79 1.763345763, 80-89 1.927443543, ge90 2.018752269; age<85 CCI 0 0, 1-3 0.612122574, 4-5 0.825072847, 6-9 0.956099733, ge10 1.395164653; age>=85 any CCI 1.529325519; unadjusted Charlson; not VACS 1.0; not VACS 2.0

Citation

Title: Development and validation of a 30-day mortality index based on pre-existing medical administrative data from 13,323 COVID-19 patients: The Veterans Health Administration COVID-19 (VACO) Index
Authors: King JT Jr, Yoon JS, Rentsch CT, Tate JP, Park LS, Kidwai-Khan F, et al.
Source: PLoS One. 2020;15(11):e0241825
DOI: 10.1371/journal.pone.0241825

Worked example

Female, age 40, CCI 0, no MI or PVD

Given: age=40cci=0mi_pvd=falsesex=female

age 40 → 20-50 term -2.228678713; female 0; CCI 0 and age<85 → 0; mi_pvd false → 0
lp = -4.216058062 - 2.228678713 = -6.444736775
estimated_probability_percent = 100 × exp(lp)/(1+exp(lp))

S3 example: 77-year-old male, CCI 5, no MI or PVD

Given: age=77cci=5mi_pvd=falsesex=male

age 77 → 75-79 term 1.763345763; male 0.322291449; CCI 5 and age<85 → 0.825072847; mi_pvd false → 0
lp = -4.216058062 + 1.763345763 + 0.322291449 + 0.825072847 = -1.305348003
S3 prints 21%; estimated_probability_percent from the unrounded logit is 21.33

Also searched as

VACO Index
VA COVID-19 Index
King 2020 30-day mortality
Veterans Health Administration COVID-19
Charlson COVID mortality
VACO 30-day all-cause mortality
King VACO logistic

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/vaco?age=40&sex=female&cci=0&mi_pvd=false

Full URL: https://api.magentlab.com/api/calc/vaco?age=40&sex=female&cci=0&mi_pvd=false

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/vaco?age=40&sex=female&cci=0&mi_pvd=false"

Parameters

Name	Type	Required	Description
`age`	integer	required	Age in years (integer 20-120). King 2020 S3 bands: 20-50 (ages 20-49), 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-89, ge90. Age 50 uses 50-54. Age 85-89 keeps the 80-89 age term and the age>=85 CCI term.
`sex`	string	required · female, male	Sex as assigned by the caller. female is the S3 reference (0). male adds 0.322291449. magent does not assign sex.
`cci`	integer	required	Unadjusted Charlson comorbidity index as assigned by the caller (integer 0-37). King 2020 S3: 0 (reference), 1-3, 4-5, 6-9, ge10 when age<85. Age 85 or older uses the published combined CCI term regardless of this integer. magent does not assign Charlson diagnoses.
`mi_pvd`	boolean	required	History of myocardial infarction or peripheral vascular disease as assigned by the caller (true or false). false is the S3 reference (0). true adds 0.267265312.

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.

POST /api/calc/vaco Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 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 (fixture)

{
  "items": [
    {
      "age": "40",
      "cci": "0",
      "mi_pvd": "false",
      "sex": "female"
    },
    {
      "age": "40",
      "cci": "0",
      "mi_pvd": "false",
      "sex": "female"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/vaco",
  "items": [
    {
      "age": 40,
      "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": "King JT Jr, Yoon JS, Rentsch CT, Tate JP, Park LS, Kidwai-Khan F, et al.",
        "doi": "10.1371/journal.pone.0241825",
        "id": "king-2020-vaco",
        "pmid": "33175863",
        "source": "PLoS One. 2020;15(11):e0241825",
        "title": "Development and validation of a 30-day mortality index based on pre-existing medical administrative data from 13,323 COVID-19 patients: The Veterans Health Administration COVID-19 (VACO) Index"
      },
      "formula": "vaco",
      "formula_expression": "lp = intercept + age_term + sex_term + cci_term + mi_pvd_term; probability = exp(lp)/(1+exp(lp)); King 2020 S1 File (PLOS S3); intercept -4.216058062; female 0; male 0.322291449; no MI/PVD 0; MI or PVD 0.267265312; age 20-50 (ages 20-49) -2.228678713, 50-54 0, 55-59 0.400599289, 60-64 0.941322019, 65-69 1.295007128, 70-74 1.629533438, 75-79 1.763345763, 80-89 1.927443543, ge90 2.018752269; age<85 CCI 0 0, 1-3 0.612122574, 4-5 0.825072847, 6-9 0.956099733, ge10 1.395164653; age>=85 any CCI 1.529325519; unadjusted Charlson; not VACS 1.0; not VACS 2.0",
      "sex": "female",
      "estimated_probability_percent": 0.16,
      "logit": -6.444737,
      "cci": 0,
      "age_band": "20-50",
      "cci_band": "0",
      "mi_pvd": false
    },
    {
      "age": 40,
      "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": "King JT Jr, Yoon JS, Rentsch CT, Tate JP, Park LS, Kidwai-Khan F, et al.",
        "doi": "10.1371/journal.pone.0241825",
        "id": "king-2020-vaco",
        "pmid": "33175863",
        "source": "PLoS One. 2020;15(11):e0241825",
        "title": "Development and validation of a 30-day mortality index based on pre-existing medical administrative data from 13,323 COVID-19 patients: The Veterans Health Administration COVID-19 (VACO) Index"
      },
      "formula": "vaco",
      "formula_expression": "lp = intercept + age_term + sex_term + cci_term + mi_pvd_term; probability = exp(lp)/(1+exp(lp)); King 2020 S1 File (PLOS S3); intercept -4.216058062; female 0; male 0.322291449; no MI/PVD 0; MI or PVD 0.267265312; age 20-50 (ages 20-49) -2.228678713, 50-54 0, 55-59 0.400599289, 60-64 0.941322019, 65-69 1.295007128, 70-74 1.629533438, 75-79 1.763345763, 80-89 1.927443543, ge90 2.018752269; age<85 CCI 0 0, 1-3 0.612122574, 4-5 0.825072847, 6-9 0.956099733, ge10 1.395164653; age>=85 any CCI 1.529325519; unadjusted Charlson; not VACS 1.0; not VACS 2.0",
      "sex": "female",
      "estimated_probability_percent": 0.16,
      "logit": -6.444737,
      "cci": 0,
      "age_band": "20-50",
      "cci_band": "0",
      "mi_pvd": false
    }
  ]
}

Response

Field	Type	Description
`formula`	string	vaco
`formula_expression`	string	King 2020 S3 logistic linear predictor and probability
`age`	integer	Input age in years
`sex`	string	female or male
`cci`	integer	Caller-assigned unadjusted Charlson comorbidity index
`mi_pvd`	boolean	Caller-assigned history of myocardial infarction or peripheral vascular disease
`age_band`	string	S3 age band used for the age term (20-50, 50-54, …, ge90)
`cci_band`	string	S3 CCI band, or age_ge85_any when age is 85 or older
`logit`	number	Unrounded linear predictor, 6 decimals
`estimated_probability_percent`	number	30-day all-cause mortality percent from the unrounded logit, 2 decimals
`citation`	object	King 2020 VACO Index citation
`disclaimer`	string	Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "age": 40,
  "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": "King JT Jr, Yoon JS, Rentsch CT, Tate JP, Park LS, Kidwai-Khan F, et al.",
    "doi": "10.1371/journal.pone.0241825",
    "id": "king-2020-vaco",
    "pmid": "33175863",
    "source": "PLoS One. 2020;15(11):e0241825",
    "title": "Development and validation of a 30-day mortality index based on pre-existing medical administrative data from 13,323 COVID-19 patients: The Veterans Health Administration COVID-19 (VACO) Index"
  },
  "formula": "vaco",
  "formula_expression": "lp = intercept + age_term + sex_term + cci_term + mi_pvd_term; probability = exp(lp)/(1+exp(lp)); King 2020 S1 File (PLOS S3); intercept -4.216058062; female 0; male 0.322291449; no MI/PVD 0; MI or PVD 0.267265312; age 20-50 (ages 20-49) -2.228678713, 50-54 0, 55-59 0.400599289, 60-64 0.941322019, 65-69 1.295007128, 70-74 1.629533438, 75-79 1.763345763, 80-89 1.927443543, ge90 2.018752269; age<85 CCI 0 0, 1-3 0.612122574, 4-5 0.825072847, 6-9 0.956099733, ge10 1.395164653; age>=85 any CCI 1.529325519; unadjusted Charlson; not VACS 1.0; not VACS 2.0",
  "sex": "female",
  "estimated_probability_percent": 0.16,
  "logit": -6.444737,
  "cci": 0,
  "age_band": "20-50",
  "cci_band": "0",
  "mi_pvd": false
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP	Code	When
400	`invalid_vaco`	VACO Index inputs must match King 2020 age, sex, Charlson comorbidity index, and myocardial infarction or peripheral vascular disease. Returned before settlement; you are not charged.
400	`invalid_items`	POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400	`invalid_item_count`	items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400	`invalid_item`	each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

4C — Sum the Knight 2020 ISARIC 4C Mortality Score items and return the published Table 5 band (low, intermediate, high, or very high).
PRIEST — Sum the Goodacre 2021 PRIEST points from NEWS2 Chart 1 Scale 1 vitals, alertness, inspired oxygen, age, sex, and performance status, and return whether the total is ≤4.
CHOSEN — Sum the Levine 2020 CHOSEN (COVID Home Safely Now) Figure 2 points from age, oxygen saturation, and serum albumin in g/dL, and return whether the total is at or above the printed cutpoint of 30.

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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /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.