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G8 geriatric screening tool
G8
Sum the eight Bellera 2012 G8 items (seven MNA items A, B, C, E, F, H, P plus age) and return whether the published ≤14 impaired-screen cutoff is met.
Markdown: /docs/g8.md · Canonical: https://magentlab.com/docs/g8
Not a medical device. Not a diagnosis, dose, or listing recommendation.
What it computes
Sum the eight Bellera 2012 G8 items (seven MNA items A, B, C, E, F, H, P plus age) and return whether the published ≤14 impaired-screen cutoff is met.
When to use
When an agent already has caller-assigned G8 bands for an older cancer patient and needs the published 0–17 total, not a comprehensive geriatric assessment, chemotherapy order, ONCODAGE/Soubeyran 2014 result, or VES-13. magent does not interview or weigh the patient.
When not to use
- Not a medical device.
- Not a chemotherapy order. This tool does not start, stop, or choose cancer treatment.
- Not a comprehensive geriatric assessment (CGA). Score ≤14 is an impaired screen from Bellera 2012; magent does not perform CGA.
- Bellera 2012 G8 only (seven MNA items A, B, C, E, F, H, P plus age). Not Soubeyran 2014 ONCODAGE validation and not VES-13.
- Caller assigns food intake, weight loss, mobility, neuropsychological, BMI, medication, health-vs-peers, and age bands. magent does not interview or weigh the patient and does not compute BMI from height and weight.
- Higher scores are better. Total 0–17. Cutoff ≤14 is the Bellera 2012 threshold that maximized AUC. Health unknown scores 0.5 (not integer-rounded).
Formula
G8 (Bellera 2012) = food_intake (severe_decrease 0, moderate_decrease 1, no_decrease 2) + weight_loss (gt_3kg 0, unknown 1, 1_to_3kg 2, none 3) + mobility (bed_or_chair 0, bed_chair_no_out 1, goes_out 2) + neuropsychological (severe 0, mild 1, none 2) + bmi (lt_19 0, 19_to_lt_21 1, 21_to_lt_23 2, ge_23 3) + more_than_3_medications (true 0, false 1) + health_vs_peers (not_as_good 0, unknown 0.5, as_good 1, better 2) + age_band (gt_85 0, 80_to_85 1, lt_80 2); seven MNA items A,B,C,E,F,H,P plus age; max 17; higher is better; <=14 impaired screen; half-point on health unknown; not Soubeyran 2014 ONCODAGE; not VES-13
Citation
- Authors
- Bellera CA, Rainfray M, Mathoulin-Pélissier S, et al.
- Source
- Ann Oncol. 2012;23(8):2166-2172
Worked example
All best poles
Given:
age_band=lt_80bmi=ge_23food_intake=no_decreasehealth_vs_peers=bettermobility=goes_outmore_than_3_medications=falseneuropsychological=noneweight_loss=none
- food_intake no_decrease → 2; weight_loss none → 3; mobility goes_out → 2; neuropsychological none → 2; bmi ge_23 → 3; more_than_3_medications false → 1; health_vs_peers better → 2; age_band lt_80 → 2
- Score = 17 (max 17); at_or_below_cutoff false (not ≤14)
Severe food-intake decrease and age >85 crosses ≤14
Given:
age_band=gt_85bmi=ge_23food_intake=severe_decreasehealth_vs_peers=bettermobility=goes_outmore_than_3_medications=falseneuropsychological=noneweight_loss=none
- Same best poles except food_intake severe_decrease → 0 (instead of 2) and age_band gt_85 → 0 (instead of 2)
- Score = 13 (max 17); at_or_below_cutoff true (≤14 impaired screen). Not a CGA.
Also searched as
- G8
- G-8
- G8 geriatric screening tool
- Bellera G8
- geriatric 8
- G8 older cancer patients
- G8 questionnaire
- G8 MNA screen
Try
Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.
Full URL: https://api.magentlab.com/api/calc/g8?food_intake=no_decrease&weight_loss=none&mobility=goes_out&neuropsychological=none&bmi=ge_23&more_than_3_medications=false&health_vs_peers=better&age_band=lt_80
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/g8?food_intake=no_decrease&weight_loss=none&mobility=goes_out&neuropsychological=none&bmi=ge_23&more_than_3_medications=false&health_vs_peers=better&age_band=lt_80"
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
food_intake |
string | required | Bellera 2012 G8 food-intake decline over 3 months (MNA item A) as assigned by the caller. severe_decrease 0, moderate_decrease 1, no_decrease 2. magent does not interview the patient. |
weight_loss |
string | required | Bellera 2012 G8 weight loss during the last 3 months (MNA item B) as assigned by the caller. gt_3kg 0, unknown 1, 1_to_3kg 2, none 3. magent does not weigh the patient. |
mobility |
string | required | Bellera 2012 G8 mobility (MNA item C) as assigned by the caller. bed_or_chair 0, bed_chair_no_out 1, goes_out 2. magent does not examine the patient. |
neuropsychological |
string | required | Bellera 2012 G8 neuropsychological problems (MNA item E) as assigned by the caller. severe 0, mild 1, none 2. magent does not interview the patient. |
bmi |
string | required | Bellera 2012 G8 BMI band (MNA item F) as assigned by the caller. lt_19 0, 19_to_lt_21 1, 21_to_lt_23 2, ge_23 3. magent does not weigh the patient or compute BMI. |
more_than_3_medications |
boolean | required | Bellera 2012 G8 takes more than 3 medications per day (MNA item H) as assigned by the caller. true scores 0; false scores 1. magent does not review the medication list. |
health_vs_peers |
string | required | Bellera 2012 G8 self-rated health versus people of the same age (MNA item P) as assigned by the caller. not_as_good 0, unknown 0.5, as_good 1, better 2. Half-point on unknown is not integer-rounded. magent does not interview the patient. |
age_band |
string | required | Bellera 2012 G8 age band as assigned by the caller. gt_85 0, 80_to_85 1, lt_80 2. magent does not assign the age band from a numeric age. |
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.
- 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_band": "lt_80",
"bmi": "ge_23",
"food_intake": "no_decrease",
"health_vs_peers": "better",
"mobility": "goes_out",
"more_than_3_medications": "false",
"neuropsychological": "none",
"weight_loss": "none"
},
{
"age_band": "lt_80",
"bmi": "ge_23",
"food_intake": "no_decrease",
"health_vs_peers": "better",
"mobility": "goes_out",
"more_than_3_medications": "false",
"neuropsychological": "none",
"weight_loss": "none"
}
]
}
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/g8",
"items": [
{
"components": [
{
"value": "no_decrease",
"factor": "food_intake",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "weight_loss",
"points": 3,
"present": true
},
{
"value": "goes_out",
"factor": "mobility",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "neuropsychological",
"points": 2,
"present": true
},
{
"value": "ge_23",
"factor": "bmi",
"points": 3,
"present": true
},
{
"value": false,
"factor": "more_than_3_medications",
"points": 1,
"present": true
},
{
"value": "better",
"factor": "health_vs_peers",
"points": 2,
"present": true
},
{
"value": "lt_80",
"factor": "age_band",
"points": 2,
"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": "Bellera CA, Rainfray M, Mathoulin-Pélissier S, et al.",
"doi": "10.1093/annonc/mdr587",
"id": "bellera-2012",
"pmid": "22250183",
"source": "Ann Oncol. 2012;23(8):2166-2172",
"title": "Screening older cancer patients: first evaluation of the G-8 geriatric screening tool"
},
"formula": "g8",
"formula_expression": "G8 (Bellera 2012) = food_intake (severe_decrease 0, moderate_decrease 1, no_decrease 2) + weight_loss (gt_3kg 0, unknown 1, 1_to_3kg 2, none 3) + mobility (bed_or_chair 0, bed_chair_no_out 1, goes_out 2) + neuropsychological (severe 0, mild 1, none 2) + bmi (lt_19 0, 19_to_lt_21 1, 21_to_lt_23 2, ge_23 3) + more_than_3_medications (true 0, false 1) + health_vs_peers (not_as_good 0, unknown 0.5, as_good 1, better 2) + age_band (gt_85 0, 80_to_85 1, lt_80 2); seven MNA items A,B,C,E,F,H,P plus age; max 17; higher is better; <=14 impaired screen; half-point on health unknown; not Soubeyran 2014 ONCODAGE; not VES-13",
"max_score": 17,
"score": 17,
"bmi": "ge_23",
"age_band": "lt_80",
"at_or_below_cutoff": false,
"food_intake": "no_decrease",
"health_vs_peers": "better",
"mobility": "goes_out",
"more_than_3_medications": false,
"neuropsychological": "none",
"weight_loss": "none"
},
{
"components": [
{
"value": "no_decrease",
"factor": "food_intake",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "weight_loss",
"points": 3,
"present": true
},
{
"value": "goes_out",
"factor": "mobility",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "neuropsychological",
"points": 2,
"present": true
},
{
"value": "ge_23",
"factor": "bmi",
"points": 3,
"present": true
},
{
"value": false,
"factor": "more_than_3_medications",
"points": 1,
"present": true
},
{
"value": "better",
"factor": "health_vs_peers",
"points": 2,
"present": true
},
{
"value": "lt_80",
"factor": "age_band",
"points": 2,
"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": "Bellera CA, Rainfray M, Mathoulin-Pélissier S, et al.",
"doi": "10.1093/annonc/mdr587",
"id": "bellera-2012",
"pmid": "22250183",
"source": "Ann Oncol. 2012;23(8):2166-2172",
"title": "Screening older cancer patients: first evaluation of the G-8 geriatric screening tool"
},
"formula": "g8",
"formula_expression": "G8 (Bellera 2012) = food_intake (severe_decrease 0, moderate_decrease 1, no_decrease 2) + weight_loss (gt_3kg 0, unknown 1, 1_to_3kg 2, none 3) + mobility (bed_or_chair 0, bed_chair_no_out 1, goes_out 2) + neuropsychological (severe 0, mild 1, none 2) + bmi (lt_19 0, 19_to_lt_21 1, 21_to_lt_23 2, ge_23 3) + more_than_3_medications (true 0, false 1) + health_vs_peers (not_as_good 0, unknown 0.5, as_good 1, better 2) + age_band (gt_85 0, 80_to_85 1, lt_80 2); seven MNA items A,B,C,E,F,H,P plus age; max 17; higher is better; <=14 impaired screen; half-point on health unknown; not Soubeyran 2014 ONCODAGE; not VES-13",
"max_score": 17,
"score": 17,
"bmi": "ge_23",
"age_band": "lt_80",
"at_or_below_cutoff": false,
"food_intake": "no_decrease",
"health_vs_peers": "better",
"mobility": "goes_out",
"more_than_3_medications": false,
"neuropsychological": "none",
"weight_loss": "none"
}
]
}
Response
| Field | Type | Description |
|---|---|---|
formula |
string | g8 |
formula_expression |
string | Exact expression used |
score |
number | Bellera 2012 G8 points 0-17 (higher is better; half-points allowed on health unknown) |
max_score |
integer | Always 17 |
at_or_below_cutoff |
boolean | true when score is <=14 (Bellera 2012 impaired screen that maximized AUC). Not a CGA and not a chemotherapy order. |
food_intake |
string | severe_decrease, moderate_decrease, or no_decrease |
weight_loss |
string | gt_3kg, unknown, 1_to_3kg, or none |
mobility |
string | bed_or_chair, bed_chair_no_out, or goes_out |
neuropsychological |
string | severe, mild, or none |
bmi |
string | lt_19, 19_to_lt_21, 21_to_lt_23, or ge_23 |
more_than_3_medications |
boolean | true if more than 3 medications per day |
health_vs_peers |
string | not_as_good, unknown, as_good, or better |
age_band |
string | gt_85, 80_to_85, or lt_80 |
components |
array | Per-item points |
citation |
object | Bellera 2012 citation |
disclaimer |
string | Not-a-device notice |
Example JSON
Machine form of the same example. Frozen fixture. Not a live lookup.
{
"components": [
{
"value": "no_decrease",
"factor": "food_intake",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "weight_loss",
"points": 3,
"present": true
},
{
"value": "goes_out",
"factor": "mobility",
"points": 2,
"present": true
},
{
"value": "none",
"factor": "neuropsychological",
"points": 2,
"present": true
},
{
"value": "ge_23",
"factor": "bmi",
"points": 3,
"present": true
},
{
"value": false,
"factor": "more_than_3_medications",
"points": 1,
"present": true
},
{
"value": "better",
"factor": "health_vs_peers",
"points": 2,
"present": true
},
{
"value": "lt_80",
"factor": "age_band",
"points": 2,
"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": "Bellera CA, Rainfray M, Mathoulin-Pélissier S, et al.",
"doi": "10.1093/annonc/mdr587",
"id": "bellera-2012",
"pmid": "22250183",
"source": "Ann Oncol. 2012;23(8):2166-2172",
"title": "Screening older cancer patients: first evaluation of the G-8 geriatric screening tool"
},
"formula": "g8",
"formula_expression": "G8 (Bellera 2012) = food_intake (severe_decrease 0, moderate_decrease 1, no_decrease 2) + weight_loss (gt_3kg 0, unknown 1, 1_to_3kg 2, none 3) + mobility (bed_or_chair 0, bed_chair_no_out 1, goes_out 2) + neuropsychological (severe 0, mild 1, none 2) + bmi (lt_19 0, 19_to_lt_21 1, 21_to_lt_23 2, ge_23 3) + more_than_3_medications (true 0, false 1) + health_vs_peers (not_as_good 0, unknown 0.5, as_good 1, better 2) + age_band (gt_85 0, 80_to_85 1, lt_80 2); seven MNA items A,B,C,E,F,H,P plus age; max 17; higher is better; <=14 impaired screen; half-point on health unknown; not Soubeyran 2014 ONCODAGE; not VES-13",
"max_score": 17,
"score": 17,
"bmi": "ge_23",
"age_band": "lt_80",
"at_or_below_cutoff": false,
"food_intake": "no_decrease",
"health_vs_peers": "better",
"mobility": "goes_out",
"more_than_3_medications": false,
"neuropsychological": "none",
"weight_loss": "none"
}
Client errors (HTTP 400)
Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.
| HTTP | Code | When |
|---|---|---|
| 400 | invalid_g8 |
G8 geriatric screening inputs must match Bellera 2012 food intake, weight loss, mobility, neuropsychological, BMI, medications, health, and age bands from that paper. 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
- Charlson CCI — Sum the nineteen Charlson 1987 original comorbidity weights and return the published 1-year mortality group.
- NRI — Apply the VA TPN Cooperative Study 1991 Nutritional Risk Index from caller-supplied albumin and current/usual weight.
- MUST — Sum Stratton 2004 MUST (BMI, unplanned weight-loss percent, and acute disease with no nutritional intake >5 days) and return score 0–6 with risk low, medium, or high.
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.