01 · The Question
What happens when the thing you are searching for used to have another name?
A literature search can span decades while terminology does not stand still. An intervention may begin under a development code and later receive a standardized name. A condition may be renamed or reclassified. A technology may pass through several labels as it develops. An institution may merge, rebrand, or change its official name.
If you search only the current name, will databases find records published under the older one?
Sometimes indexing and controlled vocabulary will help, but you should not assume that every historical record has been retrospectively connected to today's terminology. Older records can also be harder to retrieve because titles, abstracts, and indexing practices have changed over time. The safest approach is to investigate the naming history when older evidence matters to your question.
03 · What You Need to Know
Names change, but bibliographic records preserve their history
A current name does not rewrite an old publication
When something is renamed, previously published titles and abstracts generally retain the terminology used when they were written. A free-text search for the current name therefore cannot be assumed to retrieve every older record.
This problem becomes more consequential as the historical depth of the search increases. Cochrane's technical guidance cautions that older articles can be harder to identify than recent ones. Among other differences, MEDLINE records for many publications before 1976 do not contain abstracts, meaning that text-word searching for those records may effectively depend on titles and other available fields.
If the terminology in that title predates the current name, searching only contemporary language can create a historical blind spot.
Not every name change is the same kind of change
Before treating an old and new name as synonyms, determine what actually changed.
| Type of change |
What may have happened |
Main search question |
| Simple renaming |
The label changed while the underlying entity remained substantially continuous |
Do older records use only the former name? |
| Development-stage naming |
An intervention or technology had a code or provisional name before its established name |
Do early studies use the development identifier? |
| Reclassification |
The terminology changed together with conceptual or diagnostic boundaries |
Does the historical category correspond to the current eligible concept? |
| Rebranding |
A commercial technology, intervention, or organization adopted a new public name |
Which names appear during the relevant periods? |
| Institutional restructuring |
Organizations merged, split, changed status, or were renamed |
Does the old institution represent the same organizational unit you intend to study? |
The distinction matters because a historical name can be lexically related to the current one without being conceptually or organizationally equivalent.
Trace the naming history before building the search
For a consequential search, create a simple chronology. Record the current name, known previous names, abbreviations, development identifiers, dates of major changes, and the sources establishing those relationships.
Authoritative sources will depend on the entity. Drug regulators and trial registries may document intervention names. Professional classifications and controlled vocabularies can clarify condition terminology. Official organizational histories may document institutional mergers and renamings. Technical standards, product documentation, patents, or archival records may help with technologies.
Then compare those names with the terminology appearing in known relevant records. Cochrane recommends identifying free-text terms from titles, abstracts, author keywords, relevant reviews, dictionaries, and database thesauri rather than assuming that one preferred expression captures natural-language variation.
Historical names can behave like synonyms without being permanent synonyms
Suppose an institution changed its name in 2005 without otherwise changing the organizational unit relevant to your research. For retrieval purposes, the pre-2005 and post-2005 names may function as alternatives.
Now suppose two institutions merged and a new organization emerged. The earlier names are not simply synonyms for the later organization. Studies involving the predecessor institutions may or may not satisfy your eligibility criteria.
Historical name continuity
The name changed, but the entity or concept remains sufficiently continuous for both names to represent the target of the search.
Historical conceptual change
The change in name accompanies a meaningful change in what the category, intervention, technology, or organization represents.
If the concept itself changed, use the same caution applied when deciding whether two search terms represent genuinely different concepts.
Development codes can matter for interventions and technologies
An intervention may accumulate names over its lifecycle. Early research can appear under a laboratory designation, development code, model number, prototype name, or other identifier before a standardized or commercial name becomes established.
That creates a temporal retrieval problem similar to searching brand and generic names. Later terminology cannot be assumed to appear retrospectively in every early bibliographic record.
When early-stage evidence falls within your review period, inspect early trials, conference records, registries, patents, technical documentation, or known seminal studies for identifiers that may not appear in later publications.
Condition names require conceptual caution
Historical condition terminology can be especially complicated because renaming may accompany changes in diagnostic criteria, disease classification, scientific understanding, or the boundaries between conditions.
An older label may therefore retrieve a population that only partially overlaps the modern category. Searching it can still be appropriate for sensitivity, but eligibility should be determined from the actual characteristics of the study rather than from the historical label alone.
This differs from a simple lexical replacement. If the terminology has changed over time, reconstruct both the names and the meaning attached to them during the periods covered by your search.
Institution names create a different retrieval problem
Researchers sometimes search institutions as study settings, affiliations, research producers, policy actors, or organizational cases. Name changes can interfere with each of these searches.
An old affiliation may contain a former university, hospital, laboratory, government agency, or company name. A merger can introduce additional predecessor names. Abbreviations can also persist after the official name changes.
For institutional searching, establish whether you need organizational continuity or simply records associated with the current institution and its predecessors. Those are different questions.
Controlled vocabulary can help, but inspect historical indexing
Controlled vocabularies provide standardized subject terms that complement natural-language searching. Cochrane recommends using both controlled vocabulary and free-text terms because either approach alone can miss records.
Historical searches deserve additional scrutiny because indexing terminology can itself change. PRESS specifically asks whether relevant previous index terms are missing from a strategy.
Check the thesaurus history and scope notes where available. A current heading may map older terminology effectively, partially, or not at all.
The date range should determine how far backward you investigate
There is little value in adding a former name abandoned in 1980 if your eligible literature begins in 2015, unless the old expression somehow persisted into that period.
Conversely, a search extending across the entire history of an intervention or institution may need several generations of terminology.
Think temporally: which names were plausibly used during the years from which eligible evidence can come?
Test historical names for unique retrieval
Once you identify a former name, search it independently during development. Examine records retrieved by that name but not by your current terminology.
If it recovers relevant older evidence, you have a practical reason to retain it. If it retrieves nothing unique or mostly refers to a different historical concept, reconsider its role.
PRESS treats missing natural-language terms, previous index terms, overly broad or narrow headings, and inappropriate free-text terms as potential search-quality problems.
Do not erase historical terminology when reporting a reproducible search
If a former name was genuinely used in the executed strategy, report it accurately. Replacing it afterward with the current name would document a search different from the one performed.
This principle becomes particularly important when a former expression is now considered inappropriate. In that situation, preserve it only where methodologically necessary and distinguish its retrieval function from the terminology you use in your own prose, as discussed when older terminology is no longer appropriate.
04 · A Practical Example
Following one technology through three names
Hypothetical Example
A technology was renamed twice during its development
Imagine that you are reviewing a learning technology first described in prototype studies as Project Lumen, later released as Adaptive Learning Environment, and eventually marketed as LumenLearn.
These names are fictional. Your review includes studies from the prototype period through current use.
Establish the history Verify from reliable documentation that the three names refer to successive stages of the technology you intend to study.
Inspect known records Check early, transitional, and recent publications to see which names appear in searchable titles, abstracts, keywords, and indexing.
Check continuity Determine whether major changes between versions affect the intervention defined in your eligibility criteria.
Search the names Use justified historical and current names as alternative retrieval routes where they represent eligible versions of the technology.
Test unique retrieval Identify whether Project Lumen finds eligible early studies that Adaptive Learning Environment and LumenLearn miss.
Document Record the naming history so readers can understand why several apparently different terms represent the intervention search.
If the prototype differs so substantially that it no longer meets the eligibility criteria, its historical name should not be included merely because the later technology descended from it. Genealogy is not eligibility.
