Effectiveness of a case-based learning combined with flipped classroom approach in undergraduate pulmonary imaging education: a prospective randomized controlled study

ERCT Criteria Breakdown

• Level 1 Criteria

  • C

    Class-level RCT

    • Allocation was at the individual student level within a single course (by student ID number parity), not at the class or school level, and the intervention is not one-to-one tutoring.
    • "Due to the method of allocation based on the parity of student ID numbers, students were assigned to either a CBL-FC group (n=13) or an LBL group (n=13)."
    • Relevant Quotes: 1) "A prospective, quasi-randomized controlled study was conducted involving 26 third-year undergraduate students majoring in Medical Imaging. Due to the method of allocation based on the parity of student ID numbers, students were assigned to either a CBL-FC group (n=13) or an LBL group (n=13)." (Abstract, p. 1) 2) "A total of 26 third-year undergraduate students majoring in Medical Imaging were recruited from Shaoxing University School of Medicine... Students were divided into two groups (n=13 per group) using student ID number parity." (p. 2) 3) "This is a prospective, quasi-randomized, controlled study." (p. 2) Detailed Analysis: Criterion C requires that randomisation occur at the class level (or stronger school level), to prevent cross-group contamination, unless the intervention is a one-to-one/personal tutoring intervention in which case student-level allocation is acceptable. Here the 26 students were all third-year Medical Imaging students from a single institution, and the allocation unit was the individual student (assigned by the parity of their student ID number). This is student-level allocation within what is effectively a single class/cohort, not allocation of entire classes or schools. The intervention (CBL-FC group teaching with subgroup discussion) is a group classroom method, not a personal one-to-one tutoring intervention, so the tutoring exception does not apply. Furthermore, allocation by ID-number parity is a quasi-random (systematic) method rather than true randomisation, and both groups are within the same cohort, raising exactly the contamination concern this criterion guards against. Criterion C is not met because allocation was at the individual student level within a single cohort (by ID parity), not at the class or school level, and the intervention is not a personal tutoring exception.
  • E

    Exam-based Assessment

    • Outcomes were measured with tests developed in-house by the teaching team, not with a widely recognised standardised exam.
    • "All assessment items were developed by the teaching team and reviewed by two senior radiologists to ensure content validity and alignment with the learning objectives."
    • Relevant Quotes: 1) "The pre-intervention test consisted of 30 single-choice questions, with a total score of 100 points, designed to assess students' foundational knowledge of pulmonary imaging." (p. 4) 2) "The post-intervention test comprised 50 single-choice questions (50 points), two short-answer questions (30 points), and one case analysis question (20 points), with a total score of 100 points." (p. 4) 3) "All assessment items were developed by the teaching team and reviewed by two senior radiologists to ensure content validity and alignment with the learning objectives." (p. 4) Detailed Analysis: Criterion E requires the use of a standardised, widely recognised exam (e.g., a national curriculum or state-wide exam), not an instrument designed specifically for the study. The paper states explicitly that "All assessment items were developed by the teaching team," meaning the pre- and post-intervention tests were custom-built for this study and aligned with the study's own learning objectives. Review by two senior radiologists provides content validity but does not transform the instrument into a recognised standardised exam. There is no mention of any national, state-wide, or otherwise standardised examination being used. Custom tests aligned to the intervention are precisely the problem this criterion is designed to detect, as they can inflate apparent effectiveness. Criterion E is not met because the assessment instruments were custom-developed by the teaching team rather than being a recognised standardised exam.
  • T

    Term Duration

    • The teaching spanned only five sessions with the post-test administered three days after completion, far shorter than one academic term.
    • "A post-intervention assessment was administered to both the experimental and control groups three days after completion of the teaching sessions."
    • Relevant Quotes: 1) "The lectures were conducted using PowerPoint presentations, divided into five sessions, each lasting four hours." (p. 4) 2) "All students completed a baseline assessment three days before the teaching intervention." (p. 4) 3) "A post-intervention assessment was administered to both the experimental and control groups three days after completion of the teaching sessions." (p. 4) 4) "Third, the short-term nature of the post-intervention assessment did not allow evaluation of long-term knowledge retention or diagnostic performance." (p. 6) Detailed Analysis: Criterion T requires that outcomes be measured at least one full academic term (approximately 3-4 months) after the intervention begins. In this study the teaching module consisted of five sessions (the LBL group's sessions each lasting four hours), and the post-intervention test was administered only three days after the teaching sessions concluded. The total span from intervention start to outcome measurement is therefore at most a few weeks, and the authors themselves describe the "short-term nature of the post-intervention assessment." This is far below the one-term threshold, and there is no longer-term follow-up tracking. Criterion T is not met because outcomes were measured only days after a brief multi-session intervention, well short of a full academic term.
  • D

    Documented Control Group

    • The control (LBL) group's size, demographics, baseline scores, and instructional conditions are clearly documented.
    • "There were no significant differences between the two groups in terms of age, sex, or previous academic performance in imaging-related courses."
    • Relevant Quotes: 1) "Students were divided into two groups (n=13 per group) using student ID number parity. There were no significant differences between the two groups in terms of age, sex, or previous academic performance in imaging-related courses." (p. 2) 2) "Students in the control group received lecture-based instruction, delivered by the same instructor to ensure consistency. The lectures were conducted using PowerPoint presentations, divided into five sessions, each lasting four hours." (p. 4) 3) "Table 1 Age and gender of students in two groups... LBL group: Total (n) 13; Age (mean+/-SD) 20.50+/-0.67; Male 6; Female 7." (Table 1, p. 4) 4) "At baseline, there was no significant difference in test scores between the two groups (p=0.150), with the LBL group scoring 65.71+/-10.54 and the CBL-FC group scoring 60.00+/-8.79." (p. 4) Detailed Analysis: Criterion D requires that the control group be well-documented, including demographics, baseline performance, and the conditions/treatment it received. The paper documents the LBL control group's size (n=13), age and sex distribution (Table 1), and baseline test scores (65.71+/-10.54), and confirms that age, sex, and prior academic performance did not differ significantly between groups. It also describes precisely what the control group received (lecture-based PowerPoint instruction over five four-hour sessions by the same instructor) and that it did not receive the CBL-FC treatment. This level of detail allows a reader to judge baseline comparability and the control condition. Criterion D is met because the control group's size, demographics, baseline scores, and instructional conditions are clearly documented.

• Level 2 Criteria

  • S

    School-level RCT

    • Allocation was at the individual student level within a single institution, not at the school level.
    • "Students were divided into two groups (n=13 per group) using student ID number parity."
    • Relevant Quotes: 1) "A total of 26 third-year undergraduate students majoring in Medical Imaging were recruited from Shaoxing University School of Medicine... Students were divided into two groups (n=13 per group) using student ID number parity." (p. 2) 2) "the study was conducted at a single institution, which restricts the statistical power and generalizability of the findings." (p. 6) Detailed Analysis: Criterion S requires randomisation at the school level (the educational institution or implementing unit), with multiple schools/sites randomised between conditions. This study was conducted at a single institution (Shaoxing University School of Medicine), with 26 students from a single cohort allocated individually by student ID number parity. There is no school-level randomisation; indeed there is only one institution and one cohort. Criterion S is not met because allocation was at the individual student level within a single institution, with no school-level randomisation.
  • I

    Independent Conduct

    • The same team designed, taught, and assessed the intervention, with the same instructor delivering both conditions, and no independent third-party evaluator was involved.
    • "Students in the control group received lecture-based instruction, delivered by the same instructor to ensure consistency."
    • Relevant Quotes: 1) "All assessment items were developed by the teaching team and reviewed by two senior radiologists to ensure content validity and alignment with the learning objectives." (p. 4) 2) "Students in the control group received lecture-based instruction, delivered by the same instructor to ensure consistency." (p. 4) 3) "Authors' contributions: ZHZ and LZ involved in the study conceptualization. HJM collected and preprocessed the data. HJM conducted data analysis, results interpretation and manuscript preparation." (p. 7) 4) "To reduce potential bias, the post-intervention assessments were graded independently by two blinded raters, and discrepancies were resolved through discussion to reach consensus." (p. 4) Detailed Analysis: Criterion I requires that the study be conducted independently from those who designed the intervention, e.g., by an external evaluation team, to reduce bias. Here the same teaching team designed the intervention, developed the assessment items, delivered the teaching (with the same instructor delivering both the CBL-FC and LBL conditions), and analysed the data. The only element of independence is that two blinded raters graded the post-intervention assessments, but these raters operated within the same study team and do not constitute an external, third-party evaluation of the trial as a whole. There is no statement of any independent evaluator or third-party oversight of design, conduct, or analysis. Criterion I is not met because the same team designed, delivered, and analysed the intervention without independent third-party conduct.
  • Y

    Year Duration

    • Because the Term Duration (T) criterion is not met, the stronger Year Duration criterion cannot be met, and the study lasted only a few weeks.
    • "A post-intervention assessment was administered to both the experimental and control groups three days after completion of the teaching sessions."
    • Relevant Quotes: 1) "The lectures were conducted using PowerPoint presentations, divided into five sessions, each lasting four hours." (p. 4) 2) "A post-intervention assessment was administered to both the experimental and control groups three days after completion of the teaching sessions." (p. 4) 3) "Third, the short-term nature of the post-intervention assessment did not allow evaluation of long-term knowledge retention or diagnostic performance." (p. 6) Detailed Analysis: Criterion Y requires that outcomes be measured at least 75% of a full academic year (roughly 9-10 months) after the intervention begins. The intervention consisted of only five sessions with the post-test three days afterwards, spanning at most a few weeks. Per the criterion-specific rule, if Term Duration (T) is not met then Year Duration (Y) cannot be met; T is not met here, and the actual duration is far below a year regardless. Criterion Y is not met because the study lasted only a few weeks, and the prerequisite Term Duration criterion (T) is not met.
  • B

    Balanced Control Group

    • Both groups received instruction on the same content from the same instructor with broadly comparable instructional time; the difference is the pedagogical method itself, not an unmatched addition of time or budget.
    • "The teaching content focused on imaging diagnosis of common pulmonary diseases."
    • Relevant Quotes: 1) "The teaching module focused on imaging diagnosis of pulmonary diseases, covering five representative conditions... The experimental group participated in a case-based learning combined with CBL-FC approach, while the control group received traditional teaching methods." (p. 2) 2) "Students in the control group received lecture-based instruction, delivered by the same instructor to ensure consistency. The lectures were conducted using PowerPoint presentations, divided into five sessions, each lasting four hours." (p. 4) 3) "In the experimental group, a CBL-FC approach with enhanced peer interaction was implemented... Five days before the class, students were provided with anonymized real clinical pulmonary CT cases, brief clinical histories, and structured guiding questions... During the class sessions, each subgroup was represented by its group leader, who presented the group's diagnostic reasoning..." (pp. 3-4) 4) "Fifth, the combined nature of the intervention, which involved CBL approach, FC model, and enhanced peer interaction, makes it challenging to isolate the individual contribution of each component." (p. 6) Detailed Analysis: Criterion B asks whether intervention and control conditions received comparable time, budget, and materials, unless any extra resource is the explicit treatment variable. Both groups were taught the same content (imaging diagnosis of the same five pulmonary conditions) by the same instructor, ensuring consistency. The control (LBL) group received five four-hour lecture sessions. The CBL-FC group received pre-class case materials and in-class discussion/presentation sessions in place of lectures. The core difference between the conditions is the pedagogical method (flipped, case-based, peer interaction) rather than a separable add-on of extra instructional time or budget given only to the intervention group; the flipped/case-based structure and peer interaction ARE the intervention being tested. Following the decision tree, the contrast is one of instructional approach on the same content with broadly comparable engagement, so the resource difference is integral to the intervention rather than an unmatched confound. (The paper does not report exact hour-for-hour matching, but the pre-class preparation and in-class discussion are inherent to the flipped/case-based method being tested, not an extra resource that should have been balanced.) Criterion B is met because both groups received instruction on the same content from the same instructor and the difference lies in the pedagogical method itself (the treatment variable), not in an unmatched addition of time or budget.

• Level 3 Criteria

  • R

    Reproduced

    • The study has not been independently replicated by a different research team, and no such replication is reported or found.
    • Relevant Quotes: 1) "The findings of this study align with previous reports highlighting the benefits of case-based learning and flipped classroom models in medical education [18, 19]. However, this study uniquely focused on undergraduate pulmonary imaging education and incorporated enhanced peer interaction through subgroup leadership and inter-group feedback." (p. 6) 2) "Future research with larger sample sizes is essential to validate these results and assess their broader applicability to other settings." (p. 6) Detailed Analysis: Criterion R requires that this specific study (or its central claim in the same context and design) be independently replicated by a different research team and published in a peer-reviewed journal. The paper explicitly notes that it "uniquely focused on undergraduate pulmonary imaging education" and calls for future research to validate the results, indicating no replication yet exists. An internet search of PubMed, Springer/BMC, and general sources identified many CBL and/or flipped-classroom trials in medical education (e.g., ventilator management training, BMC Med Educ 2025, doi 10.1186/s12909-025-08380-4; nephrology clerkship, BMC Med Educ 2021, doi 10.1186/s12909-021-02638-3; pathology education, Med (Baltim) 2022, e28782), but none replicate this specific single-cohort pulmonary-imaging CBL-FC trial with its enhanced peer-interaction design at Shaoxing University. No independent reproduction of this particular study was found. Criterion R is not met because no independent replication of this specific study was found, and the authors themselves call for future validation.
  • A

    All-subject Exams

    • Criterion E is not met and only the single subject of pulmonary imaging was assessed, so the All-subject Exams criterion fails.
    • "The teaching content focused on imaging diagnosis of common pulmonary diseases."
    • Relevant Quotes: 1) "The teaching module focused on imaging diagnosis of pulmonary diseases, covering five representative conditions: pulmonary nodules, pneumonia, lung cancer, pulmonary tuberculosis, and interstitial lung disease." (p. 2) 2) "This assessment was designed to provide a comprehensive evaluation of students' learning outcomes, including theoretical knowledge, application of imaging principles, and diagnostic reasoning based on clinical cases." (p. 4) 3) "All assessment items were developed by the teaching team..." (p. 4) Detailed Analysis: Criterion A requires that impact be measured across all main subjects using standardised exam-based assessments, and it explicitly depends on Criterion E being met. Here, Criterion E is not met (the tests were custom-developed, not standardised), which alone causes A to fail. In addition, the study assessed only a single, highly specialised topic (pulmonary imaging diagnosis) and did not assess any other subjects. Criterion A is not met because Criterion E (standardised exam) is not met and only the single subject of pulmonary imaging was assessed.
  • G

    Graduation Tracking

    • Because Year Duration (Y) is not met and the study had no follow-up beyond a few days post-intervention, there is no tracking through graduation.
    • "the short-term nature of the post-intervention assessment did not allow evaluation of long-term knowledge retention or diagnostic performance."
    • Relevant Quotes: 1) "A post-intervention assessment was administered to both the experimental and control groups three days after completion of the teaching sessions." (p. 4) 2) "Third, the short-term nature of the post-intervention assessment did not allow evaluation of long-term knowledge retention or diagnostic performance. Future studies with larger sample sizes, multi-center designs, and longer follow-up periods are needed..." (p. 6) Detailed Analysis: Criterion G requires tracking participants through to graduation to assess long-term impact, and it depends on Criterion Y being met. Y is not met here, so G fails automatically. Substantively, the study measured outcomes only three days after the teaching sessions and explicitly acknowledges that it did not evaluate long-term outcomes. An internet search for subsequent follow-up publications by the same authors (Mao, Zhao, Yang, Zhao) tracking this cohort returned no such paper; there is no graduation tracking or follow-up publication. Criterion G is not met because the prerequisite Year Duration criterion is not met and the study performed no follow-up through graduation.
  • P

    Pre-Registered

    • The paper reports no pre-registration and explicitly states "Clinical trial number: Not applicable."
    • "Clinical trial number Not applicable."
    • Relevant Quotes: 1) "Clinical trial number Not applicable." (p. 7) 2) "This study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Shaoxing people's Hospital (2026-031-01)." (p. 2) Detailed Analysis: Criterion P requires that the full study protocol be pre-registered on a public registry before data collection began, with hypotheses, methods, and planned analyses. The paper provides only an ethics committee approval number, which is not a study pre-registration, and explicitly states "Clinical trial number: Not applicable," indicating the trial was not registered. No registry platform, registration ID, or pre-registration date is mentioned anywhere in the paper, and no registration record was found in registry searches (no trial number is provided to look up). Criterion P is not met because the study reports no pre-registration and explicitly states that no clinical trial number is applicable.