In a systematic literature review, the Title-Abstract and Full-Text screening stages serve different purposes, and therefore, often require different protocols or inclusion/exclusion criteria.
Title-Abstract Screening: Broader, Preliminary Evaluation
At this stage, reviewers have access only to limited content—typically the title, and abstract.
Because of this, the protocol is generally broader to avoid unintentionally excluding potentially relevant studies too early.
It helps narrow down the pool of citations for deeper evaluation without missing key studies due to lack of detailed information.
Full-Text Screening: Detailed, In-Depth Assessment
Here, reviewers evaluate the entire article, including methods, results, and appendices.
This allows for a more specific and refined application of inclusion/exclusion criteria.
You can assess nuances such as study design, population subgroups, or the completeness of outcome data.
Example Scenario
Let’s say your objective includes:
Including systematic reviews during Title-Abstract screening to ensure a broad capture of literature for bibliographic searches.
But at the Full-Text stage, you may decide to exclude those same systematic reviews if your focus is limited to primary studies only.
This flexibility is essential for building a high-quality evidence base without introducing early-stage bias or excluding useful references prematurely.