This HTA was planned and conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) [21] guidelines and the recommendations of the Cochrane Collaboration [22]. The methodology is in accordance with the general methods of the Institute for Quality and Efficiency in Healthcare in Germany (IQWIG), version 6.1 [23]. The HTA report without the partial search update from 2023 was published in German on the funder´s website (IQWIG: https://www.iqwig.de/sich-einbringen/themencheck-medizin/berichte/ht21-02.html). The publication of the results on the sfunder´s website was a condition for the funding. The HTA is registered with PROSPERO, CRD42022299405.

Eligibility Assessment

For the efficacy and safety analyses, randomized controlled trials (RCTs), cluster-randomized trails, and randomized cross-over studies in German or English were included. Studies were included if adults (≥ 18 years) diagnosed with burnout (including diagnosis code Z73.0 ICD-10 "Burnout"), adults with elevated burnout levels on validated burnout scales (e.g. Maslach Burnout Inventory (MBI) [24]) at baseline, a population with mean elevated levels of burnout on validated burnout scales (e.g. MBI) at baseline, or employees who were unable to work due to diagnosed burnout, were studied. Interventions were included if they were explicitly labelled as "yoga" or "yogic". No restrictions were placed on the yoga tradition, length, frequency or duration of the program. Studies investigating yoga as an add-on were also included. Studies comparing yoga to (1) no treatment, (2) treatment as usual or (3) an active control intervention were eligible. Efficacy outcomes were defined as severity of burnout, remission, subjective stress, depressive symptoms, self-efficacy, health-related quality of life, mortality and adverse events. Economic, ethical, legal, social and organizational aspects were considered as well. Titles and abstracts identified during the database and hand searches were screened by two reviewers (AKK, HH) independently, with potentially eligible articles read in full by two reviewers (AKK, HH) to determine whether they met the eligibility criteria. Disagreements were discussed with a third reviewer (MS or HC) until consensus was reached. If necessary, additional information was obtained from the study authors.

Search StrategiesEfficacy and Safety

Ovid MEDLINE(R), Embase (via Ovid), Cochrane Central Register of Controlled Trials, PsycINFO, ClinicalTrials.gov, and the World Health Organization international clinical trials registry platform were searched from inception through November 29th, 2021. A search update was executed in Embase until May 9th, 2023 by AKK and MS (See supplement Tables 1 to 6 for search strategies).

Economic, Ethical, Legal, Social and Organizational Aspects

A systematic literature search for comparative health economic studies was performed in MEDLINE, EMBASE, and HTA database. Calculation of intervention costs was based on literature and expert interviews as well as German prices. To review the ethical aspects, reference was made to the identified efficacy studies, an orienting search was performed using the relevant databases (ETHMED, MEDLINE) and information from laws, regulations or directives as well as interest-dependent sources of information, for example websites of interest representatives were evaluated.

To review the social and organizational aspects, orienting searches were performed in MEDLINE and on websites of relevant institutions and associations (Robert-Koch institute, Professional Association of Yoga Teachers in Germany e. V., Yoga Vidya). To review legal aspects, an orienting search was performed using Juris, the leading online portal for legal and practical knowledge in Germany.

Data Extraction and ManagementEfficacy and Safety

Data on participants (age, gender, diagnosis), methods (randomization, allocation concealment), interventions (yoga style, frequency, and duration), control interventions (type, frequency, duration), outcomes (outcome measures, questionnaires, assessment time points), and results were independently extracted by two reviewers (AKK and MS) using an a priori data extraction form. Discrepancies were discussed with a third reviewer (HC) until consensus was reached. If necessary, study authors were contacted for additional information.

Risk of Bias of Individual Studies

The risk of selection bias, performance bias, detection bias, attrition bias, reporting bias, and other source of bias regarding efficacy studies were independently assessed by two reviewers (AKK and MS) using the IQWIG risk of bias appraisal [23]. Each domain was assessed as either, ‘yes’, ‘no’ or ‘unclear’. Discrepancies were discussed with a third reviewer (HC) until consensus was reached.

Economic, Ethical, Legal, Social and Organizational Aspects

The health economic evaluation considered intervention costs and cost-effectiveness.

The ethical evaluation considered statements on ethical aspects and arguments of yoga interventions [25, 26]. The evaluation of legal aspects was based on Brönneke 2016 [27]. Social and sociocultural aspects addressed the reciprocal interactions between examination or treatment methods and the social environment [28]. The evaluation of organizational aspects was based on Perleth 2014 [29].

Statistical Analysis

Regarding efficacy and safety, if three or more studies were available, IQWIG methodology was used to determine whether analyses should be performed using the Knapp-Hartung method or the DerSimonian-Laird method [23]. Factors possibly causing this heterogeneity were also investigated. Because of the small number of studies, neither subgroup nor sensitivity analyses nor assessment of publication bias were performed. Statistical heterogeneity between the study effects was analyzed by the test of heterogeneity with a p-value of ≤ .05 indicating significant heterogeneity. The magnitude of heterogeneity was categorized by the I2 with I2 > 25%, I2 > 50%, and I2 > 75% representing moderate, substantial, and considerable heterogeneity, respectively [30]. All analyses were performed using the Statistical Package for Social Sciences software (IBM SPSS Statistics for Windows, release 29.0; IBM Corporation, Armonk, NY).