Definition of research capacity

Based on prior concept analysis in the literature, research capacity is conceptually defined as the ability to sustainably conduct nursing research within a specific context [1]. Operationally, research capacity refers to clinical nurses’ ability to apply research knowledge and skills in the context of their clinical work. This includes key research activities such as identifying clinical problems, reviewing literature, and disseminating findings—areas further detailed in the five core dimensions listed in Table 1. This capacity can be assessed through self-reported questionnaires, evaluations by nursing managers, and objective indicators of research output, such as participation in research projects, peer-reviewed publications, and conference presentations.

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Table 1. Core dimensions for assessing clinical nurses’ research capacity.

https://doi.org/10.1371/journal.pone.0331292.t001

Study registration and review timeline

The study protocol has been registered with the International Platform for Prospective Registration of Systematic Reviews (PROSPERO) (CRD42024594322). This study will follow the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA-P) list (see S1 File) [26].

The estimated duration for each review stage is as follows: literature search (2 weeks), title and abstract screening (2 weeks), risk of bias assessment (1 week), full-text review and data extraction (4 weeks), data analysis and synthesis (4 weeks), and manuscript drafting and revision (8 weeks). The entire review is expected to be completed within approximately six months.

Review questions

1. What is the current level of research capacity among clinical nurses?
2. What are the key barriers and facilitators influencing clinical nurses’ research capacity?

The questions were developed based on the PICo framework (Population, Phenomenon of Interest, Context), as presented in Table 2.

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Table 2. Research questions structured using the PICo framework.

https://doi.org/10.1371/journal.pone.0331292.t002

Eligibility criteria

Search strategy

Eight databases—PubMed, Cochrane Library, Embase, CINAHL, Web of Science, Scopus, CNKI, and Wanfang—will be searched for English- and Chinese-language studies on clinical nurses’ research capacity. The search strategy will combine MeSH terms and free-text keywords related to clinical nurses, research capacity, and associated factors, using Boolean operators and adapted to each database’s syntax. The search will cover studies from database inception to July 2025. A sample PubMed search strategy is presented in Table 3.

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Table 3. Search strategy in PubMed.

https://doi.org/10.1371/journal.pone.0331292.t003

Data selection

All retrieved records will be imported into Covidence for management and screening, where duplicates will be removed. To minimize selection bias, two independent reviewers will screen the titles and abstracts. Discrepancies will be resolved through discussion, and if consensus cannot be reached, a third reviewer will make the final decision. The same two reviewers will then independently screen the full texts of potentially eligible studies, with disagreements resolved in the same manner.

Data extraction

A standardized electronic data extraction form will be developed based on the objectives of this review, key variables identified in the prior literature, and recommendations from the Joanna Briggs Institute (JBI) guidelines [27]. The form will be pilot-tested on three purposively selected eligible studies representing different study designs. Feedback from the pilot testing will be incorporated to refine the extraction form prior to commencing formal data extraction. Two reviewers will then independently extract data using the finalized form. Disagreements between reviewers will be addressed through discussion, and if unresolved, adjudicated by a third reviewer.

Based on the current review objectives, the form is expected to collect the following information from each included study: the basic study information (authors, country, and publication year), study design, population characteristics, research methods (study sample, measurement tools, and analysis methods), main findings, limitations, conclusions, and study quality.

Barriers are defined as factors impeding clinical nurses’ development or application of research capacity (e.g., time constraints, insufficient staffing, lack of training or mentorship). Facilitators, in contrast, are factors enhancing research engagement (e.g., institutional support, training programs, protected research time). These factors will be extracted based on author-reported classifications. Where absent, an inductive coding approach guided by Braun and Clarke’s thematic analysis will be used, with categorizations developed through team consensus [28].

Risk of bias assessment

The methodological quality and risk of bias of the included studies will be evaluated using the Mixed Methods Appraisal Tool (MMAT, 2018 version) [29]. The MMAT is specifically designed to appraise qualitative, quantitative, and mixed-methods studies. It assesses key quality criteria, including: (1) the clarity and relevance of the research aim; (2) alignment between research questions and data sources; (3) appropriateness of the study design and methodology; (4) adequacy of the sampling strategy; (5) rigor in data collection and analysis; (6) clarity in presenting results; and (7) coherence between findings and conclusions. For mixed-methods studies, the integration of qualitative and quantitative components is also examined.

Two reviewers will independently perform the quality appraisal. Any discrepancies will be resolved through discussion, or by consulting a third reviewer when necessary, to ensure the reliability and objectivity of the assessment process. The results of the quality assessment will inform the interpretation of the review findings and be reported in a summary table.

Data synthesis

Articles meeting the inclusion criteria will be categorized according to their methodological design (e.g., quantitative studies,qualitative, or mixed-methods studies). Data will be systematically extracted into standardized tables using a predefined data extraction form. Extracted variables will include study characteristics (e.g., author, year, country), sample and setting details, instruments used to assess research capacity, and reported outcomes, including associated barriers and facilitators.

Two reviewers will independently conduct a thematic synthesis of all included studies using NVivo (version 12), following Braun and Clarke’s six-phase framework [28]. To enable integration, quantitative findings will be transformed into textual descriptions (i.e., qualitized) and synthesized with qualitative data. For mixed-methods studies, qualitative and quantitative components will be analyzed separately and then integrated into the overall thematic synthesis.

A meta-analysis will not be feasible because of the expected methodological and contextual heterogeneity, including variations in study design, measurement tools, populations, and outcomes. Themes and subthemes will be generated through an iterative, reflexive process. This will involve repeated review of extracted data, continuous cross-study comparison, and refinement through multiple team meetings. Preliminary themes will be checked against the original data for accuracy and conceptual coherence. Final themes will be confirmed through collaborative team discussion and, when necessary, validated by an external researcher with subject expertise. An audit trail documenting coding decisions and theme development will be maintained to ensure transparency and trustworthiness.

Limitations

Despite the strengths of this protocol, several limitations should be acknowledged. First, due to resource constraints, only studies published in English or Chinese will be included. This language restriction may introduce publication and language bias, potentially limiting the comprehensiveness and global applicability of the findings. Second, the study population is limited to clinical nurses working in hospital settings, which may affect the generalizability of the results to nurses in non-clinical, administrative, community, or specialized roles. Third, while qualitative, quantitative, and mixed-methods studies will be included, methodological heterogeneity—such as differences in study design, measurement instruments, and healthcare contexts—may challenge data comparability and synthesis. Finally, grey literature (e.g., dissertations, theses, and unpublished reports) will be excluded, which may further increase the risk of publication bias.