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Search the world’s trial registries while keeping every source identity visible
Understand WHO ICTRP trial registration, the 24-item Trial Registration Data Set, primary registries, duplicate bridging, prospective registration and search limits.
Clinical trials take place across countries, health systems and registry infrastructures. The World Health Organization International Clinical Trials Registry Platform helps people search registration data supplied by data providers and registries around the world through a common portal.
WHO states that the ICTRP itself is not a clinical-trials registry and cannot register a trial. Registration happens through a primary registry or another appropriate registry; ICTRP provides standards, a network and a single search route into contributed records.
Did you know? The current WHO Trial Registration Data Set version 1.3.1 contains 24 items. These include identifiers, sponsors, contacts, recruitment, interventions, outcomes, ethics approval, completion information, summary results and information about sharing individual participant data.
This article treats the portal as a global discovery and transparency layer. Every important finding should retain the source registry, trial identifier, linked original record and access date.
Chapter index
Chapters 1–9: registry network, identifiers and shared fields
- 1. ICTRP coordinates a registry network
- 2. Registration happens outside WHO
- 3. Primary registries meet published criteria
- 4. The TRDS defines minimum registration information
- 5. Primary and secondary identifiers prevent ambiguity
- 6. Support and sponsorship are separate items
- 7. Public and scientific contacts serve different questions
- 8. Public and scientific titles have different jobs
- 9. Recruitment countries and status can change
Chapters 10–17: prospective registration, search, bridging and limits
- 10. Interventions and conditions need exact labels
- 11. Outcomes carry time points
- 12. Prospective registration depends on timing
- 13. The portal bridges multiple records
- 14. Bridging reduces but cannot erase every duplicate
- 15. Search results can be exported and filtered
- 16. Portal records link back to original registers
- 17. Global registry literacy supports public health
Global trial discovery works when registry identities and duplicate records are kept visible. WHO describes ICTRP as a platform that links trial registers and supports a single point of access. The central portal receives records from data providers. This helps learners read across countries without pretending every record is identical.
Try this
Evidence question: Which registry supplied the trial record you found? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Write WHO ICTRP as the discovery route and the named registry as the record source. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Keep the identifier, retrieval date and source page in the note so the route can be repeated.
Evidence checkpoint
Record the evidence object for ictrp coordinates a registry network, its identifier or version context, and one limit that must remain visible.
The WHO platform links records supplied by registries that meet stated data and quality criteria. WHO explicitly says users cannot register a trial with ICTRP because it is not itself a registry. Researchers contact a primary registry or another relevant registry. It also separates WHO aggregation from registration by a primary registry.
Try this
Evidence question: Which organisation actually assigned the trial identifier? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Follow the source link before describing where the trial was registered. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. If a field is missing, write “not shown” and follow the official documentation rather than inventing a value.
Evidence checkpoint
Record the evidence object for registration happens outside who, its identifier or version context, and one limit that must remain visible.
A common data set makes searches more comparable while source records retain their own detail. WHO primary registries must meet criteria covering content, quality and validity, accessibility, unique identification, technical capacity, administration and governance. Bridging duplicate records reduces double counting but still needs identifier checks.
Try this
Evidence question: Which criterion supports the feature you are using? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Open the registry-criteria page and connect one portal field to one criterion. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Before comparing two records, check that their object types, methods, versions and units really align.
Evidence checkpoint
Record the evidence object for primary registries meet published criteria, its identifier or version context, and one limit that must remain visible.
CHAPTER 4 OF 17 · Meet the network
4. The TRDS defines minimum registration information
Prospective registration is a timing relationship that can be checked from dates. The WHO Trial Registration Data Set defines the minimum information needed for a trial to be considered fully registered. Its 24 items create a common descriptive core. A careful note preserves the source registry and the portal access date.
Try this
Evidence question: Which TRDS items are present in the displayed record? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Make a checklist without inventing values for fields that are blank or unavailable. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Finish by naming one supported statement and one stronger statement that still needs another evidence layer.
Evidence checkpoint
Record the evidence object for the trds defines minimum registration information, its identifier or version context, and one limit that must remain visible.
CHAPTER 5 OF 17 · Read the common data set
5. Primary and secondary identifiers prevent ambiguity
Global trial discovery works when registry identities and duplicate records are kept visible. The TRDS includes the primary registry and trial number plus secondary identifiers from sponsors, other registries, funders or oversight bodies. This helps learners read across countries without pretending every record is identical.
Try this
Evidence question: Which identifier belongs to which issuing authority? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Build an identifier-authority table before searching for duplicates. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Keep the identifier, retrieval date and source page in the note so the route can be repeated.
Evidence checkpoint
Record the evidence object for primary and secondary identifiers prevent ambiguity, its identifier or version context, and one limit that must remain visible.
CHAPTER 6 OF 17 · Read the common data set
6. Support and sponsorship are separate items
The WHO platform links records supplied by registries that meet stated data and quality criteria. The data set distinguishes sources of monetary or material support, the primary sponsor and secondary sponsors. Those roles can overlap but should not be collapsed. It also separates WHO aggregation from registration by a primary registry.
Try this
Evidence question: Who funds, who sponsors and who collaborates according to the record? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Preserve the official role name beside each organisation. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. If a field is missing, write “not shown” and follow the official documentation rather than inventing a value.
Evidence checkpoint
Record the evidence object for support and sponsorship are separate items, its identifier or version context, and one limit that must remain visible.
CHAPTER 7 OF 17 · Read the common data set
7. Public and scientific contacts serve different questions
A common data set makes searches more comparable while source records retain their own detail. The TRDS defines contact information for public queries and for scientific queries. Registry guidance recommends functional institutional contact information. Bridging duplicate records reduces double counting but still needs identifier checks.
Try this
Evidence question: Which contact role fits the question? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Describe the role without copying personal details into class notes. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Before comparing two records, check that their object types, methods, versions and units really align.
Evidence checkpoint
Record the evidence object for public and scientific contacts serve different questions, its identifier or version context, and one limit that must remain visible.
CHAPTER 8 OF 17 · Read the common data set
8. Public and scientific titles have different jobs
Prospective registration is a timing relationship that can be checked from dates. A public title should be understandable to the public while the scientific title can preserve technical precision. Both help discovery and identity checking. A careful note preserves the source registry and the portal access date.
Try this
Evidence question: Do the two titles clearly refer to the same intervention and condition? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Save both titles with the trial number. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Finish by naming one supported statement and one stronger statement that still needs another evidence layer.
Evidence checkpoint
Record the evidence object for public and scientific titles have different jobs, its identifier or version context, and one limit that must remain visible.
CHAPTER 9 OF 17 · Handle duplicates and timing
9. Recruitment countries and status can change
Global trial discovery works when registry identities and duplicate records are kept visible. Records name countries of recruitment and recruitment status. These time-sensitive fields can be updated as a trial opens, closes or completes. This helps learners read across countries without pretending every record is identical.
Try this
Evidence question: What was the status on the day you checked? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Add the access date and inspect the source registry for location detail. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Keep the identifier, retrieval date and source page in the note so the route can be repeated.
Evidence checkpoint
Record the evidence object for recruitment countries and status can change, its identifier or version context, and one limit that must remain visible.
CHAPTER 10 OF 17 · Handle duplicates and timing
10. Interventions and conditions need exact labels
The WHO platform links records supplied by registries that meet stated data and quality criteria. The common data set includes health conditions and interventions. Search terms may differ across registries, languages and clinical vocabularies. It also separates WHO aggregation from registration by a primary registry.
Try this
Evidence question: Which synonyms could find the same trial? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Search a condition term, intervention term and exact identifier, then compare results. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. If a field is missing, write “not shown” and follow the official documentation rather than inventing a value.
Evidence checkpoint
Record the evidence object for interventions and conditions need exact labels, its identifier or version context, and one limit that must remain visible.
A common data set makes searches more comparable while source records retain their own detail. Primary and secondary outcomes should include names, metrics or methods and time points. A registered outcome is a plan rather than a result. Bridging duplicate records reduces double counting but still needs identifier checks.
Try this
Evidence question: Is this an outcome definition or a reported value? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Separate protocol fields from results-related fields in two columns. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Before comparing two records, check that their object types, methods, versions and units really align.
Evidence checkpoint
Record the evidence object for outcomes carry time points, its identifier or version context, and one limit that must remain visible.
CHAPTER 12 OF 17 · Handle duplicates and timing
12. Prospective registration depends on timing
Prospective registration is a timing relationship that can be checked from dates. ICTRP describes prospective registration as registration in a primary registry before recruitment of the first participant. The portal flag compares registration and first-enrolment dates. A careful note preserves the source registry and the portal access date.
Try this
Evidence question: Which two dates support the flag? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Record both dates and state the comparison rule. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Finish by naming one supported statement and one stronger statement that still needs another evidence layer.
Evidence checkpoint
Record the evidence object for prospective registration depends on timing, its identifier or version context, and one limit that must remain visible.
Global trial discovery works when registry identities and duplicate records are kept visible. A single trial can be registered in more than one registry. ICTRP groups, or bridges, records believed to concern the same trial to support unambiguous identification. This helps learners read across countries without pretending every record is identical.
Try this
Evidence question: Which identifiers and fields support the bridge? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Review every grouped source record before counting one trial. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Keep the identifier, retrieval date and source page in the note so the route can be repeated.
Evidence checkpoint
Record the evidence object for the portal bridges multiple records, its identifier or version context, and one limit that must remain visible.
CHAPTER 14 OF 17 · Verify at the source
14. Bridging reduces but cannot erase every duplicate
The WHO platform links records supplied by registries that meet stated data and quality criteria. Differences in identifiers, dates or metadata can complicate matching. A bridged group is a discovery aid that should be verified at the contributing registries. It also separates WHO aggregation from registration by a primary registry.
Try this
Evidence question: Could two displayed records still describe the same study? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Compare sponsor, intervention, sample, countries and dates. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. If a field is missing, write “not shown” and follow the official documentation rather than inventing a value.
Evidence checkpoint
Record the evidence object for bridging reduces but cannot erase every duplicate, its identifier or version context, and one limit that must remain visible.
CHAPTER 15 OF 17 · Verify at the source
15. Search results can be exported and filtered
A common data set makes searches more comparable while source records retain their own detail. WHO search guidance describes standard and advanced search, XML export and a results-available filter. A result count reflects the portal and query at that time. Bridging duplicate records reduces double counting but still needs identifier checks.
Try this
Evidence question: Which query, filter and retrieval date produced the set? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Save the search strategy beside the exported file. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Before comparing two records, check that their object types, methods, versions and units really align.
Evidence checkpoint
Record the evidence object for search results can be exported and filtered, its identifier or version context, and one limit that must remain visible.
CHAPTER 16 OF 17 · Verify at the source
16. Portal records link back to original registers
Prospective registration is a timing relationship that can be checked from dates. ICTRP search results provide links to the full original records. The source registry may contain more current or detailed information. A careful note preserves the source registry and the portal access date.
Try this
Evidence question: Which field was verified in the source record? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Follow the original link and compare status, dates and results indicators. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Finish by naming one supported statement and one stronger statement that still needs another evidence layer.
Evidence checkpoint
Record the evidence object for portal records link back to original registers, its identifier or version context, and one limit that must remain visible.
CHAPTER 17 OF 17 · Verify at the source
17. Global registry literacy supports public health
Global trial discovery works when registry identities and duplicate records are kept visible. Evidence reviewers, regulators, researchers, librarians and policy teams use registry networks to reduce selective visibility and locate ongoing work. This helps learners read across countries without pretending every record is identical.
Try this
Evidence question: Which conclusion would be distorted by double counting? Answer in three parts: identify the visible field or file, explain how it bears on the question, and state the boundary of that evidence. Preserve the database’s own object names and accession rather than flattening everything into the word ‘data’.
Try this: Create a deduplicated trial table with one row per verified study. Turn the result into a compact claim-evidence-reasoning note, then ask a partner to retrace it. Keep the identifier, retrieval date and source page in the note so the route can be repeated.
Evidence checkpoint
Record the evidence object for global registry literacy supports public health, its identifier or version context, and one limit that must remain visible.
Contents · Previous chapter · Continue at the Science Learning Hub
Global discovery stays trustworthy when the source register travels with the record
WHO ICTRP helps learners search across registry boundaries using common data fields and explicit network criteria. Its portal connects evidence; it does not replace the primary registries that create and manage records.
Save the source registry, primary and secondary identifiers, TRDS fields, prospective-registration dates, bridge group, search query, export date and original-record URL. Recheck the source before counting studies or comparing results.
| Reading object | What it can support | Question to keep visible |
|---|---|---|
| Primary registry ID | Identity assigned by the source registry | Which registry issued it? |
| TRDS field | Common registration data element | Is the value current and complete? |
| Prospective flag | Comparison of registration and first-enrolment dates | Which dates support it? |
| Bridged group | Records grouped as the same trial | Were all source records verified? |
Sources and next reading
Substantive resource claims in this article were checked against the primary pages below. A structured record is a route into evidence; it does not by itself prove a scientific conclusion. Recheck the live record, evidence labels and release context before using it in assessed work or research.
For a classroom enquiry, save a short research receipt containing the question, search terms, selected object, exact identifier, version, access date and the evidence boundary you observed. Add the file or page that supports each statement. This small routine turns browsing into accountable science learning and gives a teacher, classmate or future analyst a route they can independently follow.
Before sharing the conclusion, ask another reader to retrace the route without verbal hints. If they reach a different version, file or interpretation, improve the receipt and narrow the claim. Reproducibility begins with this practical check. It teaches careful reading, supports fair collaboration and keeps uncertainty visible while evidence moves from an online service into notes, analysis and a final explanation.
A useful final review separates five questions. What object was found? Which organisation or repository maintains it? What exact evidence was inspected? Which statement does that evidence support? What remains uncertain? Answer each question in one sentence, then connect every answer to a visible field, file or source page. This review catches common mistakes: citing a collection when a file supplied the value, treating the newest release as the analysed release, confusing permission with scientific suitability, or turning a discovery count into a conclusion. It also gives students a calm way to improve work. A missing detail becomes a next research step instead of an invitation to guess. When the route is complete, the final explanation can stay simple because the identifiers, dates, versions, limitations and supporting evidence are already organised underneath it.
Primary sources
- WHO ICTRP overview — accessed 25 October 2026.
- WHO Trial Registration Data Set — accessed 25 October 2026.
- WHO primary registries — accessed 25 October 2026.
- WHO registry criteria — accessed 25 October 2026.
- ICTRP search portal guidance — accessed 25 October 2026.