Direct comparison
Embase vs MEDLINE: Coverage and Why Both
Embase holds 17M+ records not in MEDLINE, indexes 18,098 conferences MEDLINE does not, and uses Emtree. Why systematic reviews search both, not one.
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How do Embase, MEDLINE compare side by side?
The table below compares Embase, MEDLINE across 10 procurement-relevant dimensions, from producer through systematic review role.
Side-by-side comparison
| Dimension | Embase | MEDLINE |
|---|---|---|
| Producer | Elsevier (subscription) | US National Library of Medicine; free via PubMed |
| Records | Over 50 million, including more than 17 million not in MEDLINE | Smaller; almost entirely contained within Embase |
| Active journals | 8,597, covering about 98% of MEDLINE journals plus 3,516 unique titles | Fewer titles; nearly all also indexed by Embase |
| Conference abstracts | 5.8 million abstracts from 18,098 conferences | Not covered |
| Controlled vocabulary | Emtree | MeSH |
| Vocabulary size | Over 100,000 preferred terms (MeSH terms included) and 550,000 synonyms | Approximately 30,000 preferred terms |
| Drug and device indexing | Deeper, more granular indexing for drugs and medical devices | Less granular for drugs and devices |
| Geographic emphasis | 95 countries, with deep European coverage | Broad, with a stronger North American weighting in practice |
| Indexing of shared records | MEDLINE records are re-indexed by mapping their MeSH terms into Emtree | Indexed directly with MeSH by NLM |
| Systematic review role | Recognised by regulatory bodies for comprehensive reviews; adds unique records and grey literature | Core database; free, and the usual starting point |
Common questions
Common questions about Embase vs MEDLINE
Is Embase just a bigger MEDLINE?
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Not quite. It covers about 98% of MEDLINE journals, so most of MEDLINE sits inside it, but the extra is not only "more of the same": over 17 million additional records, 3,516 unique journals and 5.8 million conference abstracts that MEDLINE does not index at all.
Do I need to search both for a systematic review?
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Yes, in practice. The overlap is large but each holds records the other does not, and regulatory bodies recognise Embase for comprehensive reviews. Searching only one leaves a known, describable gap you would have to justify.
What is the difference between Emtree and MeSH?
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Both are controlled vocabularies, but Emtree is much larger — over 100,000 preferred terms and 550,000 synonyms, against roughly 30,000 preferred terms in MeSH — and is more granular for drugs and devices. Emtree also incorporates MeSH terms.
Can I reuse my PubMed strategy in Embase?
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Not directly. Subject headings differ, so MeSH terms have to be translated into Emtree equivalents and the syntax adjusted. Running a MeSH-based strategy unchanged in Embase silently under-retrieves.
Why do conference abstracts matter?
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They surface findings earlier than journal publication and are a recognised source of unpublished or grey literature, which matters for publication-bias assessment. MEDLINE does not index them.
Is MEDLINE the same as PubMed?
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No. MEDLINE is the MeSH-indexed subset; PubMed is the search interface and contains MEDLINE plus additional records such as ahead-of-print citations. When a protocol says "MEDLINE", it usually means the indexed subset, often searched via Ovid.
Going deeper
