# CHOSEN Score Calculator (COVID Home Safely Now)

> CHOSEN Score Calculator (COVID Home Safely Now) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Computes the Levine 2020 CHOSEN score (0–55) for COVID-19 patients based on age, SpO2, and serum albumin to estimate likelihood of event-free home monitoring.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/chosen
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chosen-score-calculator-covid-home-safely-now-7a43ab7a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jyifDWhlq4kBLY_C913WY

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability chosen-score-calculator-covid-home-safely-now-7a43ab7a
```

Example prompt: Run the CHOSEN score for a 54-year-old COVID patient with an SpO2 of 97% and serum albumin of 3.9 g/dL so I can see whether their score is above the 30-point cutpoint for likely event-free status.

## When to prefer this

Choose this endpoint when you need a standardized, validated CHOSEN score computation per the exact Levine 2020 band definitions, avoiding manual point-lookup errors. Prefer it over general-purpose LLM arithmetic for auditability and consistency. Use when building clinical triage workflows, telehealth discharge tools, or retrospective research pipelines that require reproducible COVID home monitoring risk scores.

## Known failure modes

- Missing required query parameters (age, spo2_percent, albumin_g_dl) returns a 400 error
- Age outside 18–120 integer range returns validation error
- SpO2 outside 50–100 range returns validation error
- Albumin outside 1.0–6.0 g/dL range returns validation error
- Albumin provided in wrong units (g/L instead of g/dL) will silently produce incorrect score
- Payment not attached or insufficient USDC balance returns 402 Payment Required

## How this service works

Levine 2020 CHOSEN (COVID Home Safely Now): age 18-45 +5, 46-59 +2, 60-73 +1, >73 +0; SpO2 <94 +0, 94-96 +9, 97-98 +14, >98 +21; albumin g/dL <2.8 +0, 2.8-3.3 +5, 3.4-3.7 +15, >3.7 +29. Score 0-55. Cutpoint 30 (derivation sensitivity 83%, specificity 82%). Higher score favored event-free status in the paper. Not a discharge order.

## Output

Returns the computed CHOSEN score (integer 0–55) derived from age-band, SpO2-band, and albumin-band point contributions as defined in Levine 2020 Figure 2. Scores ≥30 indicate higher likelihood of event-free status based on the derivation cohort (sensitivity 83%, specificity 82%). The result is a clinical decision-support value, not a discharge order.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "age",
      "spo2_percent",
      "albumin_g_dl"
     ],
     "properties": {
      "age": {
       "type": "integer",
       "description": "Age in years (integer 18-120). Levine 2020 Figure 2: 18-45 → 5; 46-59 → 2; 60-73 → 1; >73 → 0. Age 73 scores 1; age 74 scores 0. Adults as in the derivation cohort."
      },
      "albumin_g_dl": {
       "type": "number",
       "description": "Serum albumin in g/dL (1.0-6.0). Levine 2020 Figure 2: <2.8 → 0; 2.8-3.3 → 5; 3.4-3.7 → 15; >3.7 → 29. Not g/L. magent does not assay albumin."
      },
      "spo2_percent": {
       "type": "number",
       "description": "Oxygen saturation percent (50-100). Levine 2020 Figure 2: <94 → 0; 94-96 → 9; 97-98 → 14; >98 → 21. magent does not measure SpO2."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chosen-score-calculator-covid-home-safely-now-7a43ab7a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)