ClinicalTrials .gov (CT .gov) is the largest publicly accessible registry of clinical studies, yet its registry-oriented architecture and heterogeneous adverse event (AE) terminology limit systematic pharmacovigilance (PV) analytics. AEs are typically recorded as investigator-reported text rather than standardized identifiers, requiring manual reconciliation to identify coherent safety concepts. We present the ClinicalTrials .gov Transformation Database (CTG-DB), an open-source pipeline that ingests the complete CT .gov XML archive and produces a relational database aligned to standardized AE terminology using the Medical Dictionary for Regulatory Activities (MedDRA). CTG-DB preserves arm-level denominators, represents placebo and comparator arms, and normalizes AE terminology using deterministic exact and fuzzy matching to ensure transparent and reproducible mappings. This framework enables concept-level retrieval and cross-trial aggregation for scalable placebo-referenced safety analyses and integration of clinical trial evidence into downstream PV signal detection.
Figures & tables
Unique reported AE strings
Weighted by participants affected
Mapping category
Count
Percentage (%)
Participants affected
Percentage (%)
Exact lexical match
25,407
18.41
24,382,112
88.76
Fuzzy (bigram) match
56,340
40.82
1,717,553
6.25
Unmapped
56,285
40.78
1,370,032
4.99
Total mapped
81,747
59.22
26,099,665
95.01
Total
138,032
100.00
27,469,697
100.00
Table 1: Coverage of CT.gov adverse event terms mapped to MedDRA, reported at the unique-string level and weighted by participants affected.
Figure 1: Conceptual overview of the CTG-DB relational schema showing the primary tables and relationships linking trial metadata, arm-level structures, and adverse event normalization to MedDRA. Arm-level denominators and comparator structure are preserved to support placebo-referenced cross-trial aggregation. Only principal tables and relationships are shown.
Figure 2: Arm-level adverse event proportions across anonymized investigational products (A–C) and placebo. Each bar represents the proportion of participants experiencing the MedDRA-normalized event within a single clinical trial arm. The red dashed line indicates the 75th percentile of aggregated placebo proportions and the blue dashed line indicates the maximum observed placebo proportion. Trial phase is color-coded.