{
    "action": "final",
    "content": "## Column Classification for the `ae` Dataset\n\nBased on the metadata inspection, the 39 columns in `raw.ae` classify as follows:\n\n### **Identifiers** (4 columns)\nColumns that uniquely identify entities or events:\n- **USUBJID** — Patient identifier (~219 distinct values)\n- **AESEQ** — Adverse event sequence number within patient (1-23)\n- **AESPID** — Adverse event sponsor-defined identifier (~36 distinct values)\n- **STUDYID** — Study identifier (constant: \"CDISCPILOT01\")\n\n### **Categorical Dimensions** (25 columns)\nColumns describing adverse event characteristics and classifications:\n\n**Event Classification (MedDRA hierarchy):**\n- **AETERM** — Reported term for the adverse event (~245 distinct)\n- **AELLT** — Lowest Level Term (~279 distinct)\n- **AEDECOD** — Dictionary-derived term (~245 distinct)\n- **AEHLT** — High Level Term (~223 distinct)\n- **AEHLGT** — High Level Group Term (~253 distinct)\n- **AEBODSYS** — Body System (~28 distinct)\n- **AESOC** — System Organ Class (~28 distinct)\n\n**Event Attributes:**\n- **AESEV** — Severity (3 values: MILD, MODERATE, SEVERE)\n- **AESER** — Serious event flag (2 values: N, Y)\n- **AEREL** — Relationship to study drug (5 values: ..MISSING.. to REMOTE)\n- **AEOUT** — Outcome (3 values: FATAL, NOT RECOVERED/NOT RESOLVED, RECOVERED/RESOLVED)\n- **AESCAN** — Involves cancer (2 values: N, Y)\n- **AESDISAB** — Involves disability (2 values: N, Y)\n- **AESDTH** — Results in death (2 values: N, Y)\n- **AESHOSP** — Requires hospitalization (2 values: N, Y)\n- **AESLIFE** — Life threatening (2 values: N, Y)\n\n**Constant/Missing Code Columns (all single value):**\n- **DOMAIN** — Domain code (constant: \"AE\")\n- **AELLTCD**, **AEPTCD**, **AEHLTCD**, **AEHLGTCD**, **AEBDSYCD**, **AESOCCD** — MedDRA codes (all ..MISSING..)\n- **AEACN** — Action taken (all ..MISSING..)\n- **AESCONG** — Congenital anomaly (constant: N)\n- **AESOD** — Occurred with overdose (constant: N)\n\n### **Numeric Metrics** (2 columns)\nColumns with numeric values representing study day offsets:\n- **AESTDY** — Study day of adverse event start (~149 distinct, range: -1 to 99)\n- **AEENDY** — Study day of adverse event end (~157 distinct, range: -1 to 99)\n\n*Note: These are stored as VARCHAR but contain numeric day counts relative to study reference date.*\n\n### **Dates/Times** (3 columns)\nTemporal columns tracking event timing:\n- **AEDTC** — Date of adverse event (DATE type, 326 distinct dates: 2012-07-29 to 2014-11-18)\n- **AESTDTC** — Start date/time (VARCHAR, 433 distinct, range: 1977 to 2014-11-03)\n- **AEENDTC** — End date/time (VARCHAR, 298 distinct, includes ..MISSING.. to 2014-10-31)\n\n*Note: AESTDTC and AEENDTC are stored as VARCHAR and may contain partial dates or missing values.*\n\n### **System Metadata** (5 columns)\nInternal tracking columns added during ingestion:\n- **_ingestion_timestamp** — When the data was loaded\n- **_batch_id** — Batch identifier\n- **_source_file** — Source file path\n- **_source_system** — Source system (\"api\")\n- *(One additional system column not shown in the 30-column sample)*\n\n### Summary\n- **4 identifiers** for linking and uniqueness\n- **25 categorical dimensions** for classification and filtering\n- **2 numeric metrics** (study day offsets)\n- **3 date/time columns** for temporal analysis\n- **5 system metadata columns** for data lineage"
}