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Special Articles |
1 From the Department of Nutrition and the Office of Educational Development, Schools of Medicine and Public Health, University of North Carolina at Chapel Hill.
2 Supported by grants from the National Cancer Institute (R25CA65474), the US Department of Agriculture (96-38411-2826), and the American Institute for Cancer Research.
3 Address reprint requests to M Kohlmeier, Department of Nutrition, CB#7400, University of North Carolina, McGavran Greenberg Hall, Chapel Hill, NC 27599-7400. E-mail: mkohlmeier{at}unc.edu.
| ABSTRACT |
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Objective: The goal of this study was to evaluate the instructional efficacy and acceptability of the nutrition and cancer module when used by first-year medical students.
Design: The module was used by 163 first-year medical students at the university's medical school as an obligatory component of the nutrition course. Before and after using the module, students were asked to answer multiple-choice questions concerning their knowledge and attitudes; each question had 5 possible answers.
Results: On average, students spent
3 h studying the lessons. The percentage of correct responses to 20 knowledge questions increased from 22% before the module was used to 86% immediately after its use. When a randomly selected subsample of 25% of the students took the same test 3 mo later, they answered 62% of the questions correctly. The increase in the percentage of students who felt prepared to provide advice regarding nutrition's role in cancer prevention (from 5.7% to 66.9%) suggested a successful subjective learning experience. Neither the students' initial level of interest in cancer nutrition nor their acceptance of computer-based instruction was related to learning outcome.
Conclusions: The tested module is a useful and effective aid for teaching nutritional principles of cancer prevention. The evaluation strategy helped identify areas for instructional improvement.
Key Words: Computer-based instruction cancer prevention instructional effectiveness nutrition education retention testing Nutrition and Medicine curriculum series medical school
| INTRODUCTION |
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Convinced of the value of nutrition instruction, a group of physicians, nutritionists, and educators at the University of North Carolina is developing a self-administered, computer-based curriculum in nutrition for first- and second-year medical students (4). The purpose of this study was to determine the efficacy of the then newest module, Nutrition and Cancer, especially when used by first-year medical students.
| METHODS |
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As detailed below, 20 questions for the evaluation of module efficacy were selected on the basis of an itemized analysis of a pilot study conducted 1 y earlier. For the initial test, 40 questions of similar format and scope were added to minimize recognition of questions in the later tests. In addition, subjective attitudinal questions were used with response choices based on a 5-point Likert scale. The entire set was sent to each student by e-mail with the request to reply by e-mail within 2 d. The accompanying message informed the students that they could use the 60 questions as a study guide for later exams.
Students had 2 wk to use the Nutrition and Cancer module. At the end of this period, the 20-question test, with changes in both the sequence of questions and response choices, was administered as a written exam. The students' scores on the exam counted toward their grade for the course. Students were asked again to rate their attitudes and perceived knowledge on a 5-point scale.
Two weeks later, students took a midterm exam that contained 2 independently generated questions related to the topic of cancer and nutrition. Performance on the midterm exam was compared with performance on the initial and second tests. Three months after the second test, 40 randomly selected students were asked to participate in a retention test consisting of the same 20 questions with both the sequence of questions and the order of response choices rearranged. This retention test, like the second test, was given in a controlled, written format.
Teaching materials
The material on cancer and nutrition was taught in an interactive, computer-based format that combined lessons on biochemistry, epidemiology, and practice with the video presentation of clinical information. Major topics covered by the Nutrition and Cancer module are given in Table 1
. Learning objectives and key points were provided to the students as separate printable files.
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Generation of test items
More than 100 multiple-choice questions, each with 5 possible answers, were developed and evaluated by several internal and external reviewers. The questions were grouped into 20 sets based on topics covered by the teaching module. A preliminary 60-item test set was generated by selecting the best 3 questions from each group. Eleven volunteers (first-year dental students) answered the questions on the preliminary test, both before and after the material outlined in Table 1
was presented in a conventional lecture. On the basis of the students' responses, some of the questions and answers were modified and the revised set was tested in a group of first-year medical students at the Duke University (n = 11) and Wake Forest University (n = 6) medical schools. These students had volunteered to answer the modified test questions before and after using the Nutrition and Cancer module. The test results were used to select the best questions from each triple set of related questions for the final 20-question set used in the current study.
Statistical analysis
The data were analyzed by using SAS for PC 6.03 (SAS Institute, Cary, NC). The statistical significance of instructional effects was calculated by analysis of variance. To detect associations between answers to the questions and test outcomes, correlation coefficients were calculated.
| RESULTS |
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The percentage of correct answers given before instruction was not better than would be expected if the students had chosen 1 of the 5 possible answers randomly, which indicates that students entered the study with minimal or no knowledge of the subject matter. Furthermore, reliability was very low (0.05) and the scores on the initial test were not related to the scores on the second test (r = 0.03). A review of the answers suggested that most students attempted to provide correct answers and selected their answers on the basis of commonly held fallacies. One question regarding the evolution of cancer cells was answered correctly by more students (39%) than would be expected (20%) by chance alone, presumably because the students knew some of the underlying concepts from a concurrent pathology course. The preinstructional knowledge manifested in the better than random (20%) scores on 4 of the 5 epidemiology questions could not be traced to medical school instruction.
About half of the lesson content addressed principles of carcinogenesis and mechanisms involving nutrients and cooking practices (Table 1
). Accordingly, 10 of the test questions were designed to assess learning and retention of the involved concepts and key points. The percentage of correct answers increased from 22% on the first test to 86% on the second test (P < 0.001) and was 59% on the retention test given 3 mo later. Two of the questions uncovered an instructional weakness regarding the action of phase I and phase II enzymes. The students were clearly familiar with the concepts of enzymatic carcinogen activation and detoxification and the role of specific nutritional factors modulating these activities, but they still were confused about the respective terminologies. The results also showed that use of the module succeeded in correcting some common fallacies. For example, before instruction, more than one-third of the students thought that tocopherol accumulated to toxic concentrations in the liver and most of the remaining students thought that excess vitamin E impaired LDL clearance, damaged DNA of the intestinal mucosa, or was cleaved to generate retinol. After using the module, 91% of the students knew that ascorbic acid is required for the regeneration of tocopherol and that vitamin E can become a prooxidant in persons with poor vitamin C status. Three months later, nearly as many students (84%) had retained this knowledge.
An important objective of the module was to improve the students' ability to evaluate reports and recommendations based on epidemiologic studies. Five of the questions assessed the knowledge gained in this area. The percentage of correct answers improved from 27% to 88% from the first to the second tests and was 65% 3 mo later on the retest. The results showed that most students (95%) recognized the design used in a particular study, selected suitable methods for dietary assessment (87%), and listed criteria of causality (78%). The students performed equally (88% correct answers) well in answering questions that required more critical thinking, eg, What would be appropriate advice to give a patient who wonders about a news item on purported beneficial effects of a food? Another question asked students to identify a potential confounder of a diet-cancer association (92%).
Another 5 questions addressed the scientific foundation of current treatment regimens and cancer-prevention recommendations. The percentage of correct answers increased from 23% on the first test to 87% on the second test and was 61% on the retest 3 mo later. The results again showed that some common misconceptions were corrected by the instruction. For example, one-third of the students initially thought that carotenoids in fruit and vegetables inactivate nitrosamines through their antioxidant properties or by forming complexes; however, after instruction almost all of the students knew that ascorbic acid in these foods inhibits nitrosamine formation in the stomach.
Self-assessment of skills and attitudes
During the first and second tests, the students were asked to rate their current skills and their expectations on a scale from 1 (strongly disagree with statement) to 5 (strongly agree with statement). Most students agreed or strongly agreed that it was essential for them to know about nutritional issues involving cancer, and even more of them thought so after completing the module (89.4% compared with 78.2%; P < 0.05).
After completing the module, most of the students considered themselves knowledgeable about issues involving cancer (59.8% compared with 4.5% before completing the module; P < 0.01); even more of the students thought that they could now provide advice regarding nutrition's role in cancer prevention (66.9% compared with 5.7% before completing the module; P < 0.01). However, not as many students felt sufficiently prepared to advise cancer patients about nutrition therapy after studying the material, but the increase was still significant (35.1% compared with 5.2%; P < 0.01).
There was no significant relation between the students' level of interest in the topic and the gain in test scores. Before completing the Nutrition and Cancer module, only 16.7% of the students responded that the use of computer modules is an effective way to learn. The students' responses did not predict the actual learning effect, as measured by the improvement in scores from the first to the second test.
Usage tracking
Patterns of use and duration of computer-based instruction (CBI) were recorded on floppy disks. Of 156 students, 104 (67%) returned the disks with readable files after completing the course; 3 students returned disks with damaged files. Of those who returned disks with readable files, 81 (77.9%) reviewed the entire module. Two students did not complete any of the module's 28 segments, 8 missed between 6 and 23 segments, 4 did not complete between 3 and 5 segments, and 9 missed 1 or 2 segments. There was no clear pattern to the omissions. Segments 29, which covered the clonal nature of cancer and the biochemistry of carcinogenesis, were missed most often (6.7%), possibly because the students thought they already knew this basic material.
Recorded use time included all idle times and time spent reviewing lessons and video cases, using the reference materials, and completing the practice questions. Students who completed all sections but took only one or no practice exam (n = 21) spent a median of 3.3 h (range: 1.26.1 h) on the module compared with 5.1 h (1.215.5 h) for those (n = 59) who took all 3 practice exams.
| DISCUSSION |
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Most of the students rated the Nutrition and Cancer module as useful or very useful; only 20.3% did not. Nonetheless, many students felt that the time they spent on the program was disproportionate to the grades derived from it. The median 3.3 h that was spent by those students who reviewed all sections but did not take all 3 practice exams may provide the best outward estimate for the time actually needed to complete the lessons, interactive exercises, and video cases. This value compares favorably with the
34 h that students would be expected to spend studying this material in a conventional lecture format (12 h of in-class instruction and 2 h of reading and exam preparation). As was observed by others (14), a negative attitude about the effectiveness of CBI did not appear to be a barrier to effective learning in this group of freshman medical students. Positive reception to the instruction was indicated by some students' comments that the material increased their awareness of the effect of diet on cancer risk and that they had modified their diets on the basis of the newly learned principles.
A potential strength of CBI lies in its standardized presentation, which provides opportunities to test instructional effectiveness and to correct detected weaknesses, thereby systematically improving the quality of the instruction. We identified sections in the module that did not convey information as well as intended. For example, we found that students had difficulty linking the cancer-preventive potential of cabbage to the induction of carcinogen-conjugating activity (phase II enzymes); many mistakenly thought that isothiocyanates inhibit phase I enzyme activity. Therefore, the most recent version of the Nutrition and Cancer module reflects modifications to several pages, which clarified the relative roles of phase I and phase II enzymes in carcinogen metabolism.
Currently, 7 instructional modules have been completed, each providing an average of 3 h of instruction; additional modules are in preparation (Table 3
). Medical schools can use the modules to augment their curriculums or as a framework for new nutrition courses. At this time, more than one-third (48 of 129) of medical schools in the United States use modules of the Nutrition in Medicine curriculum series for nutrition education of first- or second-year medical students. Many of these schools have provided us their results from both formal (15) and informal testing as well as specific comments from instructors. These comments have been invaluable for the further improvement of the modules. This kind of integrated process of module modification and formal efficacy testing will be necessary to generate instruction that ensures that future generations of physicians have the knowledge for appropriate nutritional interventions and the motivation to apply what they have learned.
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