The Arksey and O’Malley framework [9], Levac et al [10], and the Joanna Briggs Institute scoping review methodology [8] guided methods for this scoping review. The review is reported according to the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) [11]. See Multimedia Appendix 1 for the completed PRISMA-ScR checklist. The protocol for this review was published in JMIR Research Protocols [12].

The question for our review was, what literature is available on DR-TB case finding and which case-finding strategies are described? We looked at studies that had sought to improve DR-TB case detection.

Textbox 1 lists the inclusion and exclusion criteria for participants, concept, outcome, context, and study design.

With assistance from an information specialist, we searched the academic databases of MEDLINE (PubMed), Embase (Ovid), The Cochrane Library, Africa-Wide Information (EBSCOhost), CINAHL (EBSCOhost), Epistemonikos, and PROSPERO (The International Prospective Register of Systematic Reviews) using no language or date restrictions. These searches were conducted on August 31, 2021, and after an initial peer review of this article, an updated search was conducted on January 11, 2024.

The search string included combinations of the following 3 domains, that are (1) terms related to “TB”; (2) terms related to “drug resistance”; and (3) terms related to “case finding,” “case detection,” “screening,” “contact investigation,” and “contact tracing.”

Search strategies from each electronic database are detailed per search date in Multimedia Appendix 2.

We used Rayyan systematic review software [13] to screen titles, abstracts, and full-text articles. Decisions were blinded, except when reviewing conflicts. Reviewers screened abstracts in duplicate for inclusion. Conflicts were resolved through discussion. Full-text articles were also screened in duplicate. Disagreements were resolved through discussion to determine final inclusion.

We developed a data extraction form in Excel (Microsoft Corp). The data extraction form was applied to all primary research reports to collect standard information on each study. Textbox 2 lists the information that was collected.

One reviewer extracted data from included papers and a second reviewer (SSvW) checked the extracted data. Reviewers met regularly to determine whether their approach was consistent and in line with the research question.

We provide a narrative report with supporting tables to summarize the data. Table 1 contains definitions we used in charting, collating, summarizing, and reporting our results.

A systems-based logic model developed from a synthesis of DS-TB case-finding strategies (Figure 1) was used as a framework to describe different strategies and resulting pathways (care-seeking pathways or screening pathways).

Quality appraisal was not conducted, because this is a scoping review and our interest is in the existing evidence base, regardless of study design and quality.

We screened 3646 titles and abstracts and 236 full-text articles. We identified 6 systematic reviews and 61 primary studies (Figure 2) for inclusion. We divided primary studies into 6 different categories (themes) and described each category in more detail below. Table 2 gives an overview of the categories and references to further detail.

We identified 6 systematic reviews. Outcomes were descriptive and none of the reviews identified any randomized controlled trials. In 5 of the 6 reviews, the date of the last search was more than 5 years ago (Table 3). In reviews with the yield of TB disease as an outcome, the denominator was reported as the number of contacts evaluated or screened; however, specific definitions for “evaluated” or “screened” were not reported and the yield for a specific screening or diagnostic strategy is unknown.

We identified 61 primary studies that were not included in any of the above reviews. Primary studies were descriptive and included cross-sectional studies, prospective studies, and retrospective reviews of program data. No trials were identified. Thirty-four studies were close-contact or household-contact investigations, 17 were outbreak investigations, 3 were airline contact investigations, 5 were epidemiological analyses, 1 described a private-public partnership program, and 1 assessed the feasibility and acceptability of an e-registry program (Table 2). Case-finding pathways were seldom described clearly, for example, whether contacts were invited for screening regardless of symptoms (Figure 1, blue pathway), whether all contacts were screened for TB at home (Figure 1, orange pathway), or whether those who experienced TB symptoms were invited for further tests (Figure 1, black dashed pathway).

This scoping review charts the existing literature on DR-TB case finding. More than 60% of identified studies described DR-TB contact investigations. Included studies were all descriptive and no trials were identified. There is a lack of primary studies for inclusion in systematic reviews assessing the effectiveness, cost-effectiveness, acceptability, and feasibility of different DR-TB case-finding strategies. Case-finding strategies were not always reported in enough detail to deduce the specific pathways in our systems-based logic model (Figure 1), for example, whether symptomatic contacts were invited to a TB diagnostic service or whether contacts were screened at home or invited for screening at a health facility; however, except for target group differences, for example, contacts of DR-TB source cases compared with DS-TB source cases, and DST when presumptive DR-TB is identified, we did not note any differences between DR-TB case-finding and DS-TB case-finding strategies. Information on factors that may influence the yield of TB disease, like the number of contacts identified, screened, and evaluated, when these contacts were evaluated (baseline or follow-up), and which screening and diagnostic tools used [85] were seldom reported in detail.

Although conclusions about the most effective DR-TB case-finding strategy cannot be drawn, several reviews looked at the possible effects of active TB case finding (screening pathways in Figure 1) compared with passive TB case finding (care-seeking pathways in Figure 1) in general. Two Cochrane reviews failed to identify any studies for inclusion. Fox et al [86] aimed to compare the diagnostic yield of TB disease between active case finding and passive case finding in TB contacts but did not identify any trials for inclusion in the review. Braganza Menezes et al [87] also could not identify trials for inclusion in a review aiming to assess the effectiveness of novel methods, for example, social network analysis, of contact tracing versus the current standard of care to identify individuals with TB infection or TB disease. A review by Kranzer et al [88] included observational studies and concluded that screening compared with standard care increases the number of patients with TB disease found in the short term, but that it is unknown whether it impacts TB epidemiology. This finding was underpinned by another Cochrane review. Mhimbira et al [5] found that active case-finding strategies may result in increased case finding in the short term, but long-term outcomes were lacking. Except for the unknown effect of TB screening on TB epidemiology, the effect of screening on individual outcomes had been studied by Telisinghe et al [89] and Kranzer et al [88]. These reviews found limited patient outcome data and no difference in treatment outcomes between active and passive case findings. While it is known that screening may increase the number of identified cases, it is unclear if TB screening makes a difference to TB epidemiology and individual outcomes compared with passive case finding.

There is a need for standardization of terminology, design, and reporting of DR-TB case-finding studies, especially contact investigation studies. Future research should focus on clear definitions, methodology, and detailed descriptions of all intervention components. There is also a need for well-conducted randomized controlled trials assessing the effect of active case finding on individual outcomes and long-term TB epidemiological outcomes.

The strengths of our review included a thorough search strategy and the use of a systems-based logic model. Nevertheless, there were some limitations. We searched several databases with no date or language restriction, but we did not translate all full-text articles. Studies that were not translated (n=4) are reported in the list of excluded studies (Multimedia Appendix 4) and from the translated abstracts it seems that similar study designs were found to those of included contact investigation studies. Our review excluded patients with TB symptoms seeking care, patients diagnosed with TB, and laboratory samples or laboratory isolates because the focus of this review was on active case finding. It should therefore be noted that studies that investigated strategies to improve identification of DR-TB after clinical identification of presumptive DR-TB cases, or studies that screened laboratory samples were not part of this review. Furthermore, for collating, summarizing, and reporting the results, we initially envisaged using our systems-based logic model as a framework to describe different case-finding strategies and resulting pathways. However, reporting was incomplete and inconsistent, and we were not able to describe pathways in detail. Nevertheless, the logic model guided our interpretation of whether a case-finding study involved screening or not. Finally, for contact investigation studies, we included studies that reported on the number of individuals with TB disease diagnosed, even if the study focused on LTBI testing and treatment. This might be a reason why the screening and diagnostic pathways were not always reported in detail. However, it is important to note that in contact investigation studies, the active case-finding component and the LTBI treatment component are both important aspects of early case finding and prevention.

Existing descriptive reviews can be updated, but there is a dearth of knowledge on the effectiveness, cost-effectiveness, acceptability, and feasibility of DR-TB case-finding strategies to inform policy and practice. There is also a need for standardization of terminology, design, and reporting of DR-TB case-finding studies, especially contact investigation studies, to decrease a large amount of research waste and increase the number of studies that could be synthesized and meta-analyzed in high-impact systematic reviews in the future [90].