# G8 geriatric screening tool G8 Status: LIVE Price: $0.005 USDC `GET /api/calc/g8` HTML: https://magentlab.com/docs/g8 Markdown: https://magentlab.com/docs/g8.md 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 [Screening older cancer patients: first evaluation of the G-8 geriatric screening tool](https://doi.org/10.1093/annonc/mdr587) Bellera CA, Rainfray M, Mathoulin-Pélissier S, et al. Ann Oncol. 2012;23(8):2166-2172 DOI: [10.1093/annonc/mdr587](https://doi.org/10.1093/annonc/mdr587) ## Worked example ### All best poles Given: `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` 1. 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 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_85, bmi=ge_23, food_intake=severe_decrease, health_vs_peers=better, mobility=goes_out, more_than_3_medications=false, neuropsychological=none, weight_loss=none` 1. Same best poles except food_intake severe_decrease → 0 (instead of 2) and age_band gt_85 → 0 (instead of 2) 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 ## Parameters - `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. Method: `POST /api/calc/g8` 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_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" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/g8 Example 200: ```json { "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 fields - `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 Frozen fixture. Not a live lookup. ```json { "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" } ``` ## Errors - HTTP 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. - 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 - [Charlson CCI](https://magentlab.com/docs/charlson) — Sum the nineteen Charlson 1987 original comorbidity weights and return the published 1-year mortality group. - [NRI](https://magentlab.com/docs/nri) — Apply the VA TPN Cooperative Study 1991 Nutritional Risk Index from caller-supplied albumin and current/usual weight. - [MUST](https://magentlab.com/docs/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. - 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.