Scientific Training in the Leiden Medical School Preclinical Curriculum to Prepare Students for their Research Projects

Friedo W. Dekker, Ph.D., Nynke Halbesma, M.Sc., Eva A. Zeestraten, Esther M. Vogelpoel, M.A., Marja T. Blees, M.A., Peter G.M. de Jong, Ph.D.

Leiden University Medical Center

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In the undergraduate curriculum of Leiden Medical School, special attention is paid to the scientific training of all students. A four year transmodular program is offered which is fully integrated into the medical curriculum. The aspect of critical appraisal of scientific reports is a core element of the training, as well as development of several scientific skills needed for participation in research projects. The program aims to improve the skills of all students and to encourage those students with over-average academic ambitions to develop their skills further by voluntary courses and participation in high level medical research projects. The program is considered to be successful as a relatively high number of the Leiden medical students publish in scientific journals even before graduation.


New knowledge in the field of medicine revises our understanding of the field with an increasingly rapid rate. It is important for physicians to be able to keep up-to-date with advancements and new developments in their fields of expertise. In general these new developments are published in the almost unlimited number of scientific research journals. For this reason, the AAMC-HHMI Committee recently indicated that students in medicine have to be supported to build a strong scientific foundation for future medical practice and have to be equipped with knowledge, skills and habits of mind to integrate new scientific discovery into their medical practice throughout their professional lives and to share this knowledge with patients and other health care professionals.1

Medical information from many other sources in addition to scientific journals comes across a doctor’s desk, including advertisements and promotions from pharmaceutical companies. In many of these, research findings are reported with fancy graphs and references to support and add credibility to the message. However, it has been shown that many claims in such advertisements are not sufficiently evidence-based when the cited references are verified.2 It is therefore essential that physicians also learn to judge the information presented and to separate “the wheat from the chaff”. To this end, they must be able to read and critically appraise the many scientific papers that are published, which requires a specific additional set of skills.

All medical schools aim to deliver good physicians. Scientific training and research opportunities are often provided as part of the curriculum. At the Leiden University Medical Center (LUMC) scientific research training is provided for all undergraduate students, where the aspect of critical appraisal of scientific reports is a core element.

In addition, those students with over-average academic ambitions are encouraged to develop their skills even more by voluntary courses and participation in high level medical research projects. In this paper, we describe the function and nature of this scientific training for medical students and discuss some of its outcomes.


Leiden Medical School is one of the eight state based medical schools in the Netherlands. Students enter Medical School after finishing secondary school education at an age of approximately 18 years old. Entry is mainly a centralized national process based on a numerus fixus system in which the government determines the number of first year students allowed to enter. Currently for Leiden Medical School this annual number is 325 first-year students. Undergraduate medical education consists typically of a 3-year Bachelor and a 3-year Master phase. There is no national exit exam and approximately 90% of all students entering Medical School finally graduate.3

The Leiden Medical School curriculum comprises a 3.5-year preclinical bachelor phase that offers general theoretical training, followed by a 2.5-year clinical master phase, consisting of internships at the LUMC or one of the associated general hospitals in the region. The preclinical, theoretical phase is patient-oriented and case-based: medical theory is always presented in relationship to real patient cases. The first two years focus on physiology and pathophysiology, whereas the third and fourth year are based on diseases, reproduction and aging using the Clinical Presentations model as developed in Calgary.4 The entire preclinical phase is structured into multidisciplinary modules of 3 or 6 weeks. Educational formats used include: large group lectures and small group tutorials, interactive seminars, self-study activities, e-learning and early patient encounters. Typical small group size is 14 students. Each module is concluded with an individual paper-based exam that must be passed. Some subjects are not presented in modules, but in transmodular courses that are integrated with the modules and run throughout the year. These courses are concluded by an exam or by means of continuous assessment.

In the clinical phase students are divided into small groups of 14 students. Every two weeks one of these groups starts its 2.5 year of training. The first 1.5 years are spent in clinical clerkships of 2 to 10 weeks. In these clerkships the students are trained on the spot and experience an increasing level of responsibility in medical practice. During this period of clerkships 9 main disciplines are visited. All the students spend the last year of the clinical phase on scientific research in one or more research projects in the LUMC or another medical center in the Netherlands or abroad. Students can also choose to perform the scientific research projects just before entering the clinical clerkships, depending on availability and personal preferences.


The scientific training program of Leiden Medical School consists of several modules offered in the preclinical phase of the curriculum.

Courses in year 1

During the first year of Medical School, the basics of epidemiology and biostatistics are discussed in the three-week course in public health. However, the main scientific training activity in this year is the transmodular course- Communication in Science (CiS). During this course all first-year students attend several lectures and participate in tutorials, during which they learn how to structure a scientific article and apply the standards of the scientific community. The basic principles of referencing and avoiding plagiarism are practiced, as well as rewriting strategies. Student pairs write a review article in Dutch and discuss their writing and that of other students by means of peer review, whereby the tutor acts as moderator. The CiS teaching concept is based on theories from sociolinguistics and discourse analysis. The main objective is for students to understand the function of language within their specific language community and how to apply language in the most effective way in professional interactive settings. In order to communicate effectively, students must further be aware of how they can amplify their strengths and diminish their weaknesses in these settings. Key topics such as audience interaction, the use of specific formats for scientific writing and presenting, the meaning of conventions, writing and speaking from the audience perspective and acknowledgment of sources, are taught and extensive personal feedback is provided. The original CiS program was designed in 1984. Since then, the CiS program has evolved into an integrated, transmodular course in written and oral scientific presentation skills in Dutch and English.

Courses in year 2

In the second year, students follow a three-week course in scientific training. The course focuses on several specific scientific skills and forms the foundation for scientific thinking and acting. It offers training in different study-designs and the basics of statistical data analysis. Also an integrated presentation skills course is offered on presenting the results of a research study in group meetings to colleagues. In the training, the conventions, rules and principles underlying an effective presentation in an academic setting are introduced and individual (video) feedback on a student’s own performance is provided. Finally the ideas of the great philosophers, such as Plato, Hume and Popper are presented and discussed in six large group lectures.

During the course the students perform an individual assignment. First, in a small group setting the students discuss and judge a peer-reviewed article. During this meeting key issues concerning the reliability of randomized controlled trials (RCTs), such as randomization, treatment allocation and blinding are discussed. After the meeting, the students receive two original RCTs from peer-reviewed journals, on which claims in medical advertisements are based. For this assignment the students use the JAMA journal guidelines.5 In this way, during the course one hundred and fifty RCTs are critically examined and judged on their reliability and correctness in relation to the advertisement for which they are used. Following their analysis, each year a small group of students continue these investigations. The conclusion of the investigation as performed in 2005 was that claims can be easily misleading, and thus advertisements should be critically appraised. This conclusion was written by a few students and published.2 Results of the investigations of recent years are currently in preparation for publication.

Courses in year 3

Evidence-based medicine is the core of a three-week course on Clinical Medicine at the beginning of the more clinically oriented third year of the curriculum. Starting with a case of a patient presenting with pain in the chest, all steps in clinical diagnostic reasoning are made explicit. The concept of prior probability of disease is explained in a Bayesian context, and students learn how to estimate posterior probability conditional on a specific test result using sensitivity and specificity of a test reported in the literature. Students apply these skills in critical appraisal of a paper on the value of spiral CT in making the diagnosis of pulmonary embolism. For choosing a proper treatment, a decision tree is explained. Instead of a normal written exam, each student gets a written description of either a male or a female patient with a certain age, specific combination of a medical history, clinical symptoms, and laboratory values. All students have to answer the same questions about their own patient in a take-home exam on which they spent 10-15 hours. Students are allowed to discuss and work together with other students, but at the end of the day they have to send in all answers to the questions concerning their own patient. Questions are related to constructing a differential diagnosis for their patient, designing a diagnostic strategy, and finding data on sensitivity and specificity of these tests in the literature. The exam contains also a few calculations on 2×2 tables, where the numbers in the tables vary between students. As a final exercise in this examination, students have to write a half page letter to their patient in response to his or her question why the proposed diagnostic strategy is better than a fictive test the patient had found on the internet. This part of the exercise tests the active understanding of the student in a semi-real life situation.

In the other clinical courses during the third year, students spend several hours studying and discussing a more scientific approach to clinical problems. In each course, a lecture is given to stimulate reflection and scientific reasoning. For example, in the course on clinical nephrology, the nephrologists explain the importance of early recognition and treatment of chronic renal failure. In a special lecture, the evidence for the effectiveness of screening programs in this field is discussed in the context of the Wilson and Jungner landmark paper on criteria for applying screening programs.6 Then students are challenged to think about the gap between what seems to be reasonable from both a pathophysiological or clinical point of view, versus the effectiveness on a wider scale.

Courses in year 4

A three-week course on practical research skills is provided in the fourth year as a final preparation for the individual research project. In this course, specific attention is paid to formulating a scientific research question and choosing a proper study design. All students read two papers and write a study protocol to advance in this line of research. In addition, they present and discuss their proposals in tutored small working groups with other students. Other topics addressed in the course are how to construct a questionnaire, data collection, and data analysis. Several lectures are given about statistical data analysis, and each student gets his own random sample from a real dataset to analyze and to prepare tables for a manuscript. Concepts, such as bias and confounding, are explained in a few lectures, and students practice in recognizing problems in published studies in a tutorial on clinical epidemiology. Writing a report and how to get a paper published is a separate topic. Finally, research ethics are discussed, including examples of scientific misconduct, fraud, and plagiarism.


In the second and third year, all students choose four out of over forty available elective courses, which are either clinically, research, or organizationally oriented. This gives students the opportunity to choose topics they are particularly interested in or wish to orientate themselves in. Developing academic skills is a core element of all elective courses, including studying the literature, discussing interpretation with other students, writing a report and giving an oral presentation, and reflecting on the broader context. In total the students spend 12 weeks full time on these four courses. Alternatively, they can choose two courses from the list and spend six weeks on other topics of their own choice. This could be a course at another (non-medical) faculty at Leiden or another university, or making a start with a research project. This project serves as a mentored learning experience and could also be the preparation for their fourth year research project.

Extra scientific training is offered to ambitious medical students. Currently three optional tracks are offered.

The Excellence Track is available for ten selected students. At the end of their first year these students are selected on the basis of motivation and high grades. In parallel to the medical curriculum they spend some 20% of their time on extra research under supervision at one of the departments of the LUMC. The selected students receive a small grant to visit scientific meetings abroad and can apply for a MD/PhD project for which two year of salary is provided by the LUMC.

An Epidemiology Track is available in which students can focus on clinical research and clinical epidemiology. In total, 12 weeks of extra courses on clinical epidemiology and biostatistics are offered. These courses are open to medical students as well as PhD students. Some courses have a classical one-week format with lectures and exercises, but recently also a master class on clinical epidemiology has been organized for which 60 students applied for only 30 available positions. This master class was organized during two weekends in a Youth Hostel. In a reading club, consisting of 14 meetings, the basic principles of the clinical epidemiology are discussed within a group of 20 medical students and two teachers. If students follow all these courses and do their scientific project in an epidemiological setting, they can apply for a formal registration as epidemiologist.

During the Biomedical Sciences Track students can follow a three-month premaster course in basic sciences. Upon successful completion, medical students can apply for a research master in Biomedical Sciences, which comprises one year of extra study, in addition to the clinical masters to become a physician.


Either just before or following their clerkships, each student does a research project for a period of 14-24 weeks full-time under supervision of a researcher. Projects are offered by most departments of the LUMC covering a wide range from basic research in a lab to translational, clinical, and epidemiological studies. Some 20-30% of the students do their research project either at another institute somewhere in The Netherlands or abroad. Before starting a student project, the research proposal must be approved by a scientific committee. Once approved, students work on their own research question which often fits in the context of a larger research project. They are involved in most phases of a research study, such as study design, data collection, and at least data analysis, interpretation, and report writing. Most students are also involved in research and other meetings organized in their department. The final report, usually in the format of a scientific paper, must be approved by the scientific committee to obtain a grade.


As stated before, the scientific research training program is offered to prepare students for their research work and to encourage academic ambitions in students. This is accomplished by offering small pieces of directed education during the first 4 years of training. Integration with the medical content of the curriculum is essential.

One of the indicators for success is the number of students that take voluntary supplementary classes and voluntarily participate in research projects. In 2005 a survey was done among Leiden medical students in their fourth year, just before starting their clerkships. The web-based questionnaire was sent to 373 students of which 252 students responded (68%). 25% of the respondents reported being involved in additional research projects beside the compulsory medical school program. Most students started doing extra research in their third year. For them, academic ambition seems to be the strongest drive. Almost 75% of the students would have preferred more information on research possibilities and additional courses.

Furthermore, the survey showed that the students who are taking extra courses and are involved in research are not only the students with the highest grades. Therefore, it seems indeed useful to offer students extra education and research possibilities. Amongst other things, this survey was a stimulation to organize and promote more additional scientific education. This led to a substantial rise in applications for scientific courses.

Another indicator to the output of the program is the number of students that actually publish work in scientific papers. An evaluation in 2005 showed that almost 20% of all Leiden Medical School students were already authors on at least one full paper listed in PubMed on the day they completed their medical study. 22% of those students even were the first author of the paper. The average number of publications by these students was 1.5 articles per student. As a result of the usually substantial publication delay, the number of students who successfully prepared a scientific paper based on a student research project before their graduation is probably even higher.


Medical students in Leiden are enthusiastic about scientific research projects and do participate in many projects voluntary. Results show that many of them are involved and publish in scientific papers. In the upcoming years the Leiden scientific training program will be extended with some more courses to meet with the wishes of the students.


The LUMC has an extensive training program for scientific skills in place. The courses from the program are integrated in the preclinical curriculum. Based on the high number of students voluntary participating in scientific courses and scientific research projects, the LUMC scientific research training program for students is considered to be successful. Students are provided with many opportunities to improve their academic skills, and many students actually take the opportunity. The number of medical students publishing in accepted peer reviewed journals is high.


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