Online-offline integrated multimodal teaching combining PBL, CBL, and CTTM to enhance clinical self-efficacy in endocrine and metabolic critical illness among internal medicine residents: a convergent parallel mixed-methods randomized controlled tria

Abstract Background Endocrine and metabolic emergencies frequently trigger clinical anxiety and reduce clinical self-efficacy among internal medicine residents. Traditional lecture-based learning (LBL) relies on one-way knowledge transmission and lacks hands-on training in critical care scenarios. According to Bandura's self-efficacy theory, insufficient clinical self-efficacy directly leads to diagnostic hesitation and decision avoidance. Although problem-based learning (PBL), case-based learning (CBL), and case three-dimensional teaching method (CTTM) each offer distinct advantages, no study has yet integrated all three into a unified online-offline teaching system or employed mixed-methods approaches to elucidate the underlying mechanisms across Bandura's four dimensions of self-efficacy. The present study addresses this gap. Methods This quantitatively driven, single-center, assessor-blinded, convergent parallel mixed-methods randomized controlled trial was conducted at the Fourth Affiliated Hospital of Anhui Medical University from September 2025 to August 2026 (Ethics Approval No.: KYXM202508021). Ninety internal medicine residents on their first endocrine rotation were enrolled and randomly assigned in a 1:1:1 ratio to a control group (LBL alone), experimental group 1 (PBL+LBL), or experimental group 2 (integrated PBL-CBL-CTTM closed-loop teaching). All three groups received a standardized 12-hour curriculum on endocrine and metabolic critical illness. Outcome measures included blinded theoretical examinations, clinical skills assessments, the General Self-Efficacy Scale (GSES), a self-developed Endocrine High-Risk Management Self-Efficacy Source Questionnaire (Cronbach's α=0.81, CVI=0.92), and a satisfaction scale. Statistical methods included one-way ANOVA with Bonferroni-corrected post-hoc pairwise comparisons (adjusted α'=0.017), chi-square tests, and receiver operating characteristic (ROC) curve analysis. For the qualitative component, 24 residents were selected via stratified purposive sampling to participate in eight 30–40 minute semi-structured focus group interviews, analyzed using the Braun & Clarke six-step thematic analysis method with NVivo 12. Quantitative and qualitative data were integrated at the interpretation stage using joint display tables to identify convergence and divergence. Results All baseline characteristics were comparable across the three groups (P>0.05). Post-intervention, experimental group 2 achieved significantly higher theoretical scores (45.10±3.12), clinical skills scores (46.20±2.41), and composite total scores (91.30±4.20) compared with the other two groups (P<0.017), with 97% of experimental group 2 participants endorsing improved critical care management ability and superior scores across all four self-efficacy dimensions. Complete convergence was observed for mastery experience, vicarious learning, and positive affect; only the verbal persuasion dimension showed partial divergence—single bedside immediate guidance had limitations, while multi-stage systematic feedback effectively compensated for this shortcoming. Conclusions The integrated PBL-CBL-CTTM teaching approach simultaneously enhances theoretical knowledge, hands-on proficiency in critical cases, and clinical self-efficacy among residents, while alleviating fear of endocrine and metabolic emergency management. The entire teaching program can be implemented at different tiers using routine hospital resources. Future studies should disentangle the independent effects of each module and conduct multi-center longitudinal follow-up to verify long-term training outcomes. Trial registration: ClinicalTrials.gov NCT07801170; date of registration: August 28, 2026; Retrospectively registered.