3.3.9 Searching for qualitative studies

The search strategy for a JBI qualitative systematic review should be conducted in three phases, as outlined in the chapter 'Search Methodology for JBI Evidence Syntheses'. Additional guidance is offered below to support the nuanced considerations needed when searching for qualitative evidence.

In qualitative systematic reviews, opinions and approaches towards the search strategy may differ, particularly the difference between a comprehensive and exhaustive search; purposive or selective search. The choice between these approaches depends on the nature of the research question, the intended outcomes of the review and the philosophical stance of the researchers.

For systematic reviews using meta-aggregation, a comprehensive search is essential (Lockwood et al. 2015). A comprehensive search strategy aims to capture all relevant studies. A well-designed strategy should systematically explore diverse databases and sources to ensure that all insights related to the phenomenon of interest are captured. This thorough approach not only strengthens the robustness of the synthesised findings but also promotes transparency and reproducibility in the research process. Additionally, a comprehensive search strategy enables researchers to identify and incorporate a broad spectrum of perspectives, enriching the synthesis with diverse voices and experiences.

A qualitative systematic review should consider papers published by both academic and commercial publishers, as well as grey literature, which can complement and communicate findings to a wider audience. The search for qualitative evidence in systematic reviews presents some challenges. Not all databases index qualitative research thoroughly. Some databases lack detailed thesaurus terms for qualitative research and/or specific qualitative methods. Changes in thesaurus terms between databases also mean that reviewers need to be cognisant of the limitations of the selected database used. It may be beneficial to expand the search to include terms that specifically capture qualitative inquiry. For instance, keywords such as “experiences,” “perspectives,” “attitudes,” and “lived experience” are commonly associated with qualitative research. Additionally, incorporating terms related to qualitative methodologies (e.g., “ethnography,” “phenomenology,” “grounded theory”) enhances the search’s sensitivity, increasing the likelihood of identifying relevant qualitative studies. As such, the help of an experienced research information specialist is recommended.

In qualitative systematic reviews, citation searching and hand searching are useful strategies to capture studies that might otherwise be missed. Unlike quantitative research, qualitative studies are often published in niche journals or collections and may use varied terminology. Citation searching, also known as reference tracking, involves looking at the references of included studies (backward citation tracking) and identifying newer studies that cite them (forward citation tracking). This process is particularly valuable in qualitative research because it uncovers articles related by topic or approach, regardless of the keywords or indexing used. Manual or "hand searching" involves browsing key journals, conference proceedings, or institutional repositories that frequently publish qualitative studies. Additional information can be found in the chapter 'Search Methodology for JBI Evidence Syntheses'. Other aspects to consider when conducting a search include:

• Timeframe chosen for the search: Justification should be provided for limiting the timeframe. Limiting the search by date may be used when the focus of the review is related to a specific period or when there have been significant changes in practice or understanding over time. However, potentially relevant studies and early seminal papers in the field may be missed if the limit set is too recent. Thus, date limits should be used in an informed way based on knowledge of key papers relevant to the review question. These papers must be cited to support the decisions made to the date limits.

• Any language restrictions: Excluding papers based on language may result in important cultural contexts or findings being missed. The exclusion of selected languages also means that the review audit trail is incomplete. It is therefore recommended that no language restrictions should be placed when searching for qualitative studies. It is recommended to search inclusively and keep a record of numbers of studies per language group. This allows the reader to identify the number of studies published in other languages which promotes transparency of the process. Additionally, many existing papers published in languages other than English are abstracted. If the translated abstract is reviewed to meet the eligibility criteria, the reviewers may decide to retrieve the full paper and seek to collaborate with other entities to support translation work. Regardless, the literature search should be based on the principle of comprehensiveness and consider the widest reasonable range of languages that are considered appropriate to the focus of the review.