Effectiveness of problem-based learning combined with lecture based learning methodology in renal pathology education

Abstract To evaluate the teaching effect of problem-based learning (PBL) combined with lecture-based learning (LBL) compared with that of LBL alone in renal pathology education for trainees receiving standardized training.A total of 65 undergraduate medical students who received standardized training in Xijing Hospital from January 2016 to November 2019 were randomly divided into a PBL+LBL group (33 subjects) and an LBL alone group (32 subjects). The teaching effect was evaluated using the subjects’ diagnostic accuracy of renal pathology, knowledge of renal pathology and teaching satisfaction assessment. The diagnostic accuracy of renal pathology, knowledge of renal pathology and teaching satisfaction assessment in PLB+LBL group (81.0%, 79.99 ± 6.65 and 89.4%, respectively) were significantly higher than those in the LBL alone group (58.5%, 62.89 ± 10.31 and 58.9%, respectively). While teaching renal pathology to undergraduate medical students receiving standardized training, the PBL+LBL group benefited from a teaching effect and gave a better teaching satisfaction.


Introduction
The clinical manifestations of renal diseases are proteinuria and/or hematuria and renal insufficiency (Cavanaugh & Okusa, 2021;Maas RJ, Wetzels JF. Glomerular disease in, 2017;Moreno et al., 2019;Wg, 2017). However, there are great differences in the pathogenesis and prognosis of Guoshuang Xu ABOUT THE AUTHOR Guoshuang Xu, male, professor, Department of Nephrology, Xijing Hospital, Fourth Military Medical University of PLA. Mainly engaged in clinical, scientific research and teaching of kidney disease. In order to improve the teaching effect and teaching satisfaction, in recent years, new teaching methods are being explored for the clinical and pathological aspects of kidney disease and peritoneal dialysis. In the teaching of renal pathology, it is found that problem-based learning (PBL) combined with lecturebased learning (LBL) has better teaching effect and teaching satisfaction than LBL alone. various renal diseases, especially glomerular diseases (Fiorentino et al., 2016). Since the successful development of renal biopsy, the understanding of renal pathology has changed in the diagnosis, treatment and prognosis of renal diseases (Zhang et al., 2014). Renal pathology is an indispensable diagnostic gold standard in modern nephrology (Hemrajani et al., 2016). Standardized training is the first-line clinical entry training for undergraduate medical students. One of the main training contents for doctors who undergo standardized training in internal medicine is renal pathology. Therefore, one of the main objectives of their training is to master the knowledge of renal pathology. For many years, our department, which has a rich teaching experience, has been in charge of training students. However, there are still some deficiencies in renal pathology teaching.
Traditionally, kidney pathology is a lecture based learning (LBL) course that includes two parts: a theory course and experimental course. In the theory course, teachers explain the concepts of diseases, the main features of pathology, and the relationship between pathology and clinical manifestations. In the experimental course, the teacher provides pictures of renal pathology, and the students listened to the teacher's explanation of renal pathology and clinical knowledge while examining the pictures, and ask questions. There is significant repetition in both theoretical and experimental courses, with the experimental course often acting as a review of the theory course. In these courses, teachers are at the center of the curriculum while students are passive learners.
Problem-based learning (PBL) is a well-researched and well established educational method based on insights into human learning (De Jong et al., 2017). As an effective means to acquire practical and clinical practice knowledge, PBL has been adopted in pre-graduation clinical education in many medical colleges (Ikegami et al., 2017). Renal pathology courses need to integrate theory, practice, perceptual knowledge and interest. Therefore, we attempted to combine PBL with LBL in 2016 as a new teaching mode in renal pathology education to achieve a better teaching effect.

Research object
From January, 2016, to December 2019, a total of 65 undergraduate medical students receiving standardized training were enrolled. Of the 65 students, 4 or 5 receive training every quarter of each year. They were randomly assigned with computer randomization to either the PBL+LBL or LBL group, 33 in the PBL+LBL group and 32 in the LBL group ( Figure 1). The computer randomization method is described briefly: dividing the students into male and female groups, each numbered with a sequential number starting with 1. Open SPSS 22.0, enter the number, set "(,)" to "(0,1)" in "Functions and Special Variables" of "Transformation" to get random numbers. Use random numbers in the "Data Editor" to obtain "1/2" samples, 1 for PBL + LBL group and 2 for LBL group.

Implementation of teaching plan
A total of 65 trainees who had standardized training in our department were randomly divided into the PBL + LBL group and the LBL group. For the PBL + LBL group, the teaching process was presided over by Teacher 1. The trainees read the pathological sections under the microscope and examined the immunofluorescence and electron microscopy images, while being provided with the clinical features and main findings of the corresponding cases. They read the pathological sections for half an hour each, after which they discussed the main pathological and clinical features, pathological diagnoses and diagnostic evidence in each subgroup for an hour. Finally, Teacher 1 uniformly explained the basic knowledge of renal pathology and clinical knowledge of kidney disease for each case half an hour. In the LBL group, trainees only received traditional infusion training of renal pathology knowledge and clinical knowledge of renal diseases from Teacher 1, who then answered students' questions. The total teaching time was two hours. Both groups studied renal pathology for two hours twice a week, with five days a week for free communication with patients.
Both groups studied for a total of 12 weeks and were tested on Friday of the 12th week. In the renal pathology knowledge test, Teachers 1, 2, and 3 showed the students the sections of various typical renal pathology and the immunofluorescence and electron microscopy images. The trainees read the pathological sections under the microscope as well as immunofluorescence and electron microscopy images. Then, were asked the following questions: ① What is the positive judgment method and clinical significance of immunofluorescence? ② What are the main features of glomerulopathy and tubulointerstitial lesions seen in pathological sections? ③ What are the main characteristics of electron microscopy? ④ What kind of pathological diagnosis should be considered in combination with immunofluorescence, pathological features and electron microscopic features? Afterward, Teacher 1 presented their comments and explanations. Meanwhile, the kidney pathology knowledge test conducted by Teacher 2 was according to the unified knowledge points, and the satisfaction survey was conducted by Teacher 3 was according to the designated questions.

Statistical treatment
An independent sample t-test was used for measurement data, while Chi square and Fisher tests were used for counting data. All data were analyzed using the SPSS 22.0 software, P < 0.05 was considered statistically significant. Table 1 shows the PBL + LBL and LBL groups' basic information. There was no significant difference between the two groups (all P > 0.05).

Accuracy of renal pathological diagnoses
We tested the students' accuracy in diagnosing common pathological types of primary glomerular disease and two common pathological types of secondary glomerular disease. The results showed that except for idiopathic membranous nephropathy (P > 0.05), the scores of the PBL + LBL group were significantly higher than those of the LBL group (all P < 0.05), as indicated in Table 2.

Knowledge of renal pathology
Based on the accuracy test of overall renal pathological diagnosis, we further analyzed the scores of the trainees in various pathological knowledge points, such as immunofluorescence, various light microscopy staining sections, and electron microscopy image judgment. The results showed that the scores of the PBL + LBL group in various pathological knowledge points were significantly higher than those of the LBL group (all P < 0.05), as seen in Table 3.

Satisfaction survey
The survey of the teaching satisfaction of the two groups found that PBL + LBL training was perceived as being significantly better than LBL training in terms of improving students' learning interest and initiative, the communication ability between teachers and students and between doctors and patients, and students' understanding ability as well as raising disease awareness (all P < 0.05), as seen in Table 4.

Discussion
In this study, we test the teaching effect of a new teaching method involving PBL+LBL. We found that the PBL+LBL teaching method has more advantages than the LBL teaching method. With the development of modern medicine, renal pathology has become an irreplaceable element in the diagnosis, treatment and prognosis of renal diseases (Fiorentino et al., 2016;Zhang et al., 2014). The PBL teaching method emphasizes students' independent inquiry and pays attention to students' problem solving process, which helps to cultivate their learning ability and interest and allows them to better understand and master knowledge ( First, we compared the renal pathology test scores of the PBL + LBL and the LBL alone groups. The results showed that the scores of the PBL + LBL group were significantly higher than those of the LBL group, not only in primary glomerulonephritis, such as minimal change disease, focal  segmental glomerulosclerosis, idiopathic membranoproliferative nephritis and IgA nephropathy, but also in diabetic nephropathy and hypertensive nephrosclerosis of secondary glomerulonephritis. The overall accuracy rate of renal pathological diagnosis in the PBL + LBL group is 22.5% higher than that in the LBL group, which strongly indicates the PBL teaching method's advantage in judging the accuracy rate of renal pathological diagnoses. However, in the test of idiopathic membranous nephropathy, we found no significant difference in scores between the two groups (P = 0.6576). This may be because of the pathological type's prominent characteristics under the light microscope and typical immunofluorescence characteristics, which are easy to distinguish from most proliferative glomerular diseases and easy to master.
Second, we collected the scores of various pathological knowledge points in immunofluorescence, light microscopy (HE staining, PAS staining, PASM staining and Masson staining), and electron microscopy in the PBL + LBL and LBL groups. The results showed that the PBL + LBL group's mastery of renal pathological knowledge points was significantly better than that of the LBL group, and the average score of the PBL + LBL group's renal pathological knowledge was 17.1 points higher than that of the LBL group. This further proves that the PBL teaching has unique advantages, ranging from kidney pathology knowledge points to comprehensive pathological diagnoses.
Finally, the survey of teaching satisfaction of the two groups found that the PBL + LBL teaching method was significantly better than the LBL method in terms of improving students' learning interest, and initiative, the communication ability between teachers and students and between doctors and patients, and students' understanding ability as well as raising disease awareness. The results showed that the PBL + LBL group scored 30.5% higher than the LBL group in overall satisfaction with teaching, which indicates that the PBL teaching method in renal pathology leads to significantly high teaching satisfaction. There have been many reports on the advantages of the PBL+LBL teaching method in students' knowledge, skill mastery and teaching satisfaction. Jia et al. found in a meta-analysis of 23 RCTs studies involving 2,589 medical students that the PBL+LBL teaching method significantly improved students' knowledge, skills, medical writing, understanding, and teaching satisfaction compared with traditional LBL teaching method . Trullas et al. also found, in their scoping review of 125 published papers, that PBL is an effective and satisfactory methodology for medical education (Trullàs et al., 2022). However, for the training of renal pathology, the question of whether PBL+LBL teaching method is better than traditional LBL teaching method had not yet been explored. Our preliminary observation found that PBL+LBL teaching method has significant advantages over traditional LBL teaching method in the teaching of renal pathology in terms of knowledge and skills mastery, learning interest, and teaching effect. Although our results are consistent with those reported in literature  and (Trullàs et al., 2022) in terms of teaching effects, our teaching objects are undergraduate medical students, who are closer to clinicians. Besides, compared with other medical knowledge, renal pathology requires more perceptual knowledge from viewing films, which may be more suitable for PBL teaching method. In addition, in the teaching process, we have added the interaction between teachers and students such as timely answering questions, which may further increase students' interest in learning.

Limitation
First, the duration of the course is short (only 3 months). A longer period would clarify the differences in benefits between the two teaching methods more convincingly. Second, the renal pathology involved in this study included common primary and secondary glomerular diseases, but did not include rare renal diseases (such as amyloidosis) and tubulointerstitial diseases. Third, considering the complexity of renal pathology of lupus nephritis, the traditional LBL teaching method is still used while teaching its renal pathology, so it was not included in this study. Fourth, the sample size of this study is not large. Therefore, we expect future research to include more extensive renal pathology knowledge and a larger sample size.

Conclusion
Due to the importance of renal pathology in nephrology and the particularity of renal pathology teaching, traditional LBL teaching is difficult for students to master in a short period of time. Based on LBL teaching, the rational application of the PBL teaching method in renal pathology education can greatly develop students' active learning ability as well as active thinking and practical application of knowledge. In our study, through PBL teaching, the mastery of knowledge points, the accuracy of pathological diagnoses, and the satisfaction of teaching improved significantly.