What a targeted literature review is
A targeted literature review (TLR) answers a defined question with a deliberately restricted search: fewer sources, narrower terms, often a single reviewer, and a synthesis built for a decision rather than for exhaustive coverage. It is not a lesser systematic review. It is a different tool, chosen when the cost of missing a study is low and the value of a fast, well-reasoned answer is high.
There is no single agreed methodology for a TLR. That is the main risk with them. A TLR with an undocumented search is an opinion with references. A TLR with a protocol, a recorded search and stated limitations is a piece of evidence that others can check and build on.
The same problem exists one step up. A scoping review of rapid review definitions (Hamel et al., Journal of Clinical Epidemiology 2021) found that the only consensus was that no formal definition existed, and identified recurring themes instead: an accelerated process, variation in methods shortcuts, a narrower scope and explicit acknowledgement of limitations. Those themes are a useful test for any TLR. If the shortcuts are not stated, the review cannot be interpreted.
When a targeted literature review is appropriate
- Early evidence planning: mapping what exists before committing to trials, real-world studies or a full systematic review.
- Disease burden and unmet need: epidemiology, natural history, current pathways and patient burden for value narratives and payer materials.
- Model inputs: supplementary parameters such as resource use, costs or utilities, where the question is narrow and well defined.
- Landscape and comparators: current and emerging treatments, guidelines and HTA decisions, often as input to PICO anticipation.
- Scoping a systematic review: testing terms, volumes and eligibility before a protocol is fixed.
The common thread is that the output informs a decision inside the company, or supplies context and secondary inputs, rather than carrying the central comparative claim in a submission. When a TLR starts to be asked to do that second job, it is time to plan a systematic review.
When HTA bodies require a systematic review
For the core clinical evidence in a submission, a TLR is usually not enough. The NICE manual (PMG36, section 3.4) states that evidence on outcomes should come from a systematic review, done to a pre-specified protocol. It also asks companies to show that resource use and cost data have been identified systematically (section 4.4.1), although reviews of published economic evaluations need not be exhaustive.[1]
For EU joint clinical assessment, the HTA Coordination Group's dossier guidance requires a systematic search for all available evidence for every PICO in the assessment scope, covering at least MEDLINE, CENTRAL and the main trial registries, with a cut-off no more than 3 months before submission. See EU JCA dossiers.[2]
Some agencies are explicit about where a focused search is acceptable. The Danish Medicines Council's literature guidance (version 1.0) requires a systematic review for clinical effectiveness and safety as a rule, but accepts focused searches for narrow data needs, particularly supplementary health economic inputs, provided they are transparent, reproducible and justified.
Methods for a transparent targeted literature review
We borrow from rapid review methods, where the evidence on which shortcuts are safe is strongest. The Cochrane Rapid Reviews Methods Group's updated guidance (Garritty et al., BMJ 2024) is our reference point:[3]
- Protocol first: question, eligibility criteria, sources and restrictions written down before searching, and agreed with the people who will use the result.
- Pragmatic but documented searching: at least two bibliographic databases where effectiveness questions are involved, with full search strings, dates and limits recorded. Targeted grey literature, HTA reports and registries are named, not described as hand searching.
- Screening checks: where one reviewer screens, a second screens a sample. Cochrane suggests dual screening of at least 20% of records, moving to single screening only if agreement is high.
- Verified extraction: one reviewer extracts, a second verifies critical data such as outcome definitions and results.
- Proportionate appraisal: validated tools applied to the outcomes that matter, rather than no appraisal at all.
- Honest reporting: every restriction and its potential effect on the findings stated plainly, with searches reported to PRISMA-S and the review adapted from PRISMA, as the Cochrane guidance recommends.
None of this makes a TLR a systematic review. It makes its limits visible, which is what allows a health economist, a medical lead or an HTA reviewer to decide how much weight it can bear.
Targeted literature review vs systematic review vs rapid review
| Targeted literature review | Rapid review | Systematic review | |
|---|---|---|---|
| Purpose | Focused answer for planning, inputs or context | Timely evidence for a decision, with defined shortcuts | Comprehensive, reproducible answer for submission |
| Protocol | Recommended, often internal | Expected, publicly available for Cochrane | Required, pre-specified |
| Searching | Selected sources and terms | Restricted but documented, at least two databases | Comprehensive, multiple databases and registries |
| Screening and extraction | Often single reviewer | Single with dual checks on a sample | Dual, independent |
| Risk of bias | Optional or light | Validated tools, key outcomes | Full, validated tools |
| Accepted as core HTA evidence | Rarely | Depends on the agency and question | Yes |
What we deliver
- Targeted literature reviews on disease burden, epidemiology, treatment pathways and unmet need
- Focused searches for model inputs: costs, resource use and utilities
- Competitive and comparator landscape reviews, including HTA decisions
- Rapid reviews to Cochrane rapid review methods
- Protocols and search documentation that can be reused in a later systematic review
- Evidence gap analysis to decide whether a systematic literature review is needed
What to get right
- The right review type: core clinical evidence for NICE or the JCA calls for a systematic review, with a TLR used where it fits.
- Documented searching: strings, dates and sources recorded, so the review can be reproduced and updated.
- Balanced inclusion: studies selected by pre-stated criteria, which reviewers can verify.
- Current searches: a TLR from early development refreshed before it supports a submission. See SLR updates.
Why Evidaxia
We conduct de novo systematic literature reviews and SLR updates for HTA, so we know what a targeted review can and cannot carry. We design TLRs so that their protocols and searches can be extended into a full systematic review when the evidence plan requires it. The same team builds the economic models that consume the inputs, so searches are scoped to the parameters the model actually needs.
References
- National Institute for Health and Care Excellence. NICE health technology evaluations: the manual (PMG36) [Internet]. London: NICE; 2022 Jan 31 [updated 2026 Oct 13; cited 2026 Oct]. Available from: https://www.nice.org.uk/process/pmg36
- Member State Coordination Group on HTA. Guidance on the JCA dossier template (medicinal products) [Internet]. Brussels: Member State Coordination Group on HTA; [date unknown] [cited 2026 Oct]. Available from: https://health.ec.europa.eu/document/download/3943ae6a-1bca-4afd-b05c-fd9a54a252d7_en?filename=hta_jca_mp_dossier-template_guidance_en.pdf
- Garritty C, Hamel C, Trivella M, Gartlehner G, Nussbaumer-Streit B, Devane D, et al. Updated recommendations for the Cochrane rapid review methods guidance for rapid reviews of effectiveness. BMJ. 2024;384:e076335. doi:10.1136/bmj-2023-076335 Available from: https://www.bmj.com/content/384/bmj-2023-076335
Sources reviewed October 2026. Methods and procedures change; check the latest agency guidance before submission.