Medical Reference Services Quarterly DXplain : A ...

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DXplain : A Web-Based Diagnostic Decision Support System for Medical Students Sue London

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Indiana University School of Medicine, Ruth Lilly Medical Library, 975 West Walnut Street, Indianapolis, IN, 46202-5121, USA Published online: 12 Oct 2008.

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To cite this article: Sue London (1998) DXplain : A Web-Based Diagnostic Decision Support System for Medical Students, Medical Reference Services Quarterly, 17:2, 17-28, DOI: 10.1300/J115v17n02_02 To link to this article: http://dx.doi.org/10.1300/J115v17n02_02

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DXplain " :


A Web-Based Diagnostic Decision Support System for Medical Students Sue London

ABSTRACT. DXplain" is a diagnostic decision support program, with a new World Wide Web interface, designed to help medical students and physicians formulate differential diagnoses based on clinical findings. It covers over 2000 diseases and 5000 clinical manifestations. DXplain suggests possible diagnoses, and provides brief descriptions of every disease in the database. Not all diseases are included, nor does DXplain take into account preexisting conditions or the chronological sequence of clinical manifestations. Despite these limitations, it is a useful educational tool, particularly for problem-based learning (PBL) cases and for students in clinical rotations, as it fills a niche not adequately covered by MEDLINE or medical texts. The system is relatively self-explanatory, requiring little or no end-user training. .Medical libraries offering, or planning to offer, their users access to Web-based materials and resources may find this system a valuable addition to their electronic collections. Should it prove popular with the local users, provision of access may also establish or enhance the library's image as a partner in medical education. [Article copies availablefor ajee from 7Yte Haworth Document Delivety Service: 1-800-342-9678.E-mail addrws: [email protected]]

Sue London is Head of Reference, Indiana University School of Medicine, Ruth Lilly Medical Library, 975 West Walnut Street, Indianapolis, IN 46202-5121 (Internet: [email protected]). She received her AMLS from the University of Michigan. Medical Reference Services Quarterly, Vol. 17(2), Summer 1998 @ 1998 by The Haworth Press, Inc. All rights reserved.

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MEDICAL REFERENCE SERVICES QUARTERLY


INTRODUCTION Diagnostic decision support systems are designed to assist physicians in formulating a differential diagnosis based on one or more clinical findings, and in obtaining summaries of known conditions. Among the most well known of these are Iliad, QMR (Quick Medical Reference), and ~ ~ ~ 1 a DXplain, i n . l the system discussed here, includes over 5000 clinical manifestations associated with more than 2000 diseases. First discussed in the biomedical literature in 1987,~DXplain was designed at the Laboratory of Computer Science (Massachusetts General Hospital). Since that time, it has been accessible in a variety of ways, including as a standalone system and via the Internet. DXplain is available for the MS DOS and Windows platforms, as well as via its new World Wide Web (WWW) interface, in beta testing as of the writing of this article. Because WWW browsers are increasing1 being used to access many types of biomedical information, DXplain's new interface may be of interest to those libraries offering, or planning to offer, Web-based resources to their users, particularly where multiple medical campuses or remote training sites exist. At Indiana University (IU), about 120 of 270 entering medical students spend their first two years at one of nine Centers for Medical Education, some located away from an IU campus, then move to a campus location for clinical training. The Ruth Lilly Medical Library (RLML) at IU, the only medical school library in Indiana, tries to be sensitive to the information needs of off-campus medical students. A number of these students have limited access to computing support and facilities, yet as of fall 1997, computer ownership is required of all incoming medical students. Some IU School of Medicine classes are being taught using problem-based learning (PBL); one Center uses PBL exclusivel PBL has bcen shown to result in heavier use of library resources, an observation informally confirmed by experience at IU. Thus, there is ongoing interest in providing support and access to resources such as DXplain as an adjunct to locally-mounted databases (including Ovid's MEDLINE and Micromedex's DRUGDEX). During a three-month trial period, beginning in January 1997, to assess Dxplain's usefulness, advertis-

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ing flyers were distributed to the mailboxes of all medical students and chief residents, and were also posted in the Library. An e-mail announcement of DXplain's availability was 'sent to all School of Medicine faculty via a listsew maintained by the Oftice of the Dean. In addition, a DXplain poster was presented at the School of Medicine's first annual "Electronic Trends in Medical Education" symposium held in April 1997. DISCUSSION

Clinical physicians and medical students in problem-based learning (PBL) curricula or clinical rotations generally approach patient cases similarly. They are given information about the initial complaint(~)and the results of any laboratory or other diagnostic tests. With that information, they are then expected to reach a conclusion as to the cause and treatment of the complaint. With experience, the students learn to eliminate some of the less likely diagnoses. A 1989 article, written from the student perspective, compares the efficiency of human memory to electronic textbooks in establishing a diagnosis5 and acknowledges the utility of computer technology in medical education. This viewpoint is increasingly encouraged by medical schools which require computers for students. However, even practicing physicians may find diagnostic possibilities a bit daunting. Dr. Anthony Voytovich, then Chief of Staff at the John Dempsey Hospital in Connecticut, said of diagnostic decision support systems, "If I see someone with a given set of symptoms, I can usually think of 20 or 30 things that it could be, off the top of my head." [A decision support system] "helps me to narrow it down to a few possible diagnose^."^ Most of the existing literature has been written about physician use of diagnostic decision support systems other than DXplain. A JAMIA editorial also points out that existing studies of these systems, because of the way in which they were done, should perhaps not be the sole basis for recommending their purchase or use.' Nevertheless, some of the findings may still be useful in a general sense for assessing the utility of DXplain for medical students. It should be noted that formal training, averaging about two hours,


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A4EDICAL REFERENCE SERVICES QUARTERLY

was part of the process in many of these study cases since outcome data were being collected, but is not necessary due to the system's fairly self-explanatory design. One study of physician use compared DXplain and three other diagnostic decision support systems. The overall average among physician searchers was two additional diagnoses, not previously considered, suggested for each of over one hundred cases entered.8 Another study, using QMR with internal medicine house staff, found that in 8 1% of thirty-one cases using real patients, a change in case management was made as a result of using the system.g Changes ranged from considering an additional diagnosis to modifying the choice or order of diagnostic tests. Among medical student studies, an Iliad study reported that students trained with cases involving uncommon diagnoses performed better than those using common cases, when later presented with an unusual case.1° A second Iliad study, with third-year students in a clinical rotation, administered six training cases followed by six test cases. A "high" correct diagnostic rate of 59% to 92% was noted on the six subsequent test cases.'' In general, then, use of diagnostic decision support systems may have a positive effect on the performance of medical students.

ACCESSING DXplain DXplain access, for both individuals and institutions, requires a signed agreement with the Laboratory of Computer Science at Massachusetts General Hospital (MGH).The library or institution provides the Intemet Protocol (IP) addresses of its potential DXplain users to MGH. No local maintenance is necessary-a bonus for libraries relying on external computer support services. As of the writing of this article, no charge was being assessed for Web-based access, but an electronic survey inquiring how much users would be willing to pay was being conducted during search sessions. Access information is available on the MGH Laboratory of Computer Science DXplain Web page: http://lcsdxplain.mgh.harvard.edu/lcshome/ dxplahhbn or by sending an e-mail message to Dr. G..Octo Bamett: [email protected]

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SEARCHING DXplairi ~ o l l o w i nis ~a sample DXplain search using a hypothetical patient who is a thirty-eight-year-oldfemale, has episodes of heartburn several tin~esa day, has had a cough for several weeks, and has recently been having trouble swallowing solid food. She has already had a normal chest x-ray. A DXplain session begins with logging in. The system is constantly undergoing revision, so user feedback is encouraged via the "Comment" option throughout the search process. During the World Wide Web (WWW) interface beta testing period, the user is asked to enter his e-mail address and to choose his professional status from a pull-down menu. The user also indicates how the system is to be used. "Enter a Case for Analysis" is used if multiple findings are to be entered; "Diseases Associated with a Finding" is used for a single entry. The user is prompted to specify whether the information is from an actual patient case or from a hypothetical case. For this search, "Enter a Case for Analysis" and "hypothetical case" are selected(see Figure 1). Next, the user selects patient demographic information (age and gender) and specifies the duration of the illness, choosing from acute, subacute, or chronic. For this hypothetical patient, "Female," "Adult, Young (18 to 40 yrs)," and "Chronic (> few days)" are selected (see Figure 2). At this point, the user can ask for help, enter a comment, or continue on to add one or more findings, which can consist of FIGURE 1 DXplain Login Screen Enteryrmremallrddms [email protected] PmfdmdStab

(

@ Enter Ia Case fur Analysls

Other Health Professional

0 Disease lnfonnatipn 0 Diseases Associated with a Finding 0 Help 0 Comment

0 Fmm an aclual case @ A hypolhetlcal case

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MEDICAL REFERENCE SERVICES QUARTERLY FIGURE.2

DXplain Patient Demographic Information Screen


P a t i e n t ~ p h i c ~ ~ Select the most appmpriate4tem fmm each category then click on the CONTINUEbutlon.

@ Continue to add finding 0 Help 0 Comment

physical findings, signs or symptoms, laboratory data, or radiologic findings. Multiple findings are separated with a semi-colon. This patient's complaints are entered as "heartburn; cough; swallowing difficulty," and the "Add Findings" button is used to indicate that this information is to be correlated with the patient demographic selections submitted earlier (see Figure 3). However, note that it is not possible to specify the order in which physical findings, signs, or symptoms occurred. Once the findings have been entered, the user can edit the list or request a list of possible diseases. The entered findings are matched against a hierarchical vocabulary list, and clarification of the intended terminology may be prompted for by the system. In this case, when the list is requested, the system prompts for more specific information about the type of cough the patient has and about the phrase "swallowing difficulty" (see Figure 4). The more specific terms "Chronic cough (> 4 weeks; normal CXR)" and "Dysphagia" are selected from the options presented.

Sue London

FIGURE 3

DXplain Enter Findings Screen Enkfindln~rsprnkdb9 ;'*.


Iheartburn; coujh; svalloving

@Add Flnding(s)

ditficulty

( Clear text field nnd REET )

CHRONIC (> FEW DAYS)

ORemovn Findings) lp OFocw on Finding(s)

OFindlng Informstion lp

0 Llst Pcsslble Dlseases 01 OEnter Dlsnase Name for lnfomaUon ONew h

e lp OHelp B1 OCommmt

LP

[Request) When appropriate terminology is prompted for and entered, the user is shown a "Current Findings List" and from that screen again requests the list of possible diseases associated with those findings (see Figure 5). The diseases presented on the list are marked with a "+" if the evidence presented is sufficient to support that diagnosis, or a " - " if the evidence is insufficient. Other diseases may be listed without a +I - designation if they fall between the two extremes in terms of the probability of being the cause of the finding(s). Note, however, that diseases within a given designation are listed randomly in that section, not in strictly descending order according to likelihood (see Figure 6). For the hypothetical patient, only one disease, "Hiatus Hernia," is sufficiently supported by the findings submitted, although there are also less likely and unlikely diseases listed. More information about any disease on the list may be obtained. Choosing "Explain Disease" displays various findings and manifestations for the disease, grouped according to how likely each is to be the.cause of that disease (see Figure 7). As with the disease list mentioned above, these findings are listed randomly within their sections. By choosing "Disease Information" instead, the user is shown



FIGURE 4 DXplain Prompt for More Specific Information

Added to findlngs Ilst: "HEARTBURN',

( Process Request 1

FIGURE 5 DXplain Current Findings List CHRONIC COUGH ( 2 4 WEEKS, N O R M CXR) HEIIRTBURN CHRONIC (> FEW DAYS)

ORemove Finding(s) El OFocus on Flnding(o) El OFindlng Information (21 @List Posslble Dlsaases 0 Enter Msesee Name forlnbmation [ID ONew Case I11 OHelp El OCornment [ID

[PloEsssRequest) much more extensive information about the disease. Detailed information may include: etiology; associated terms and conditions; symptoms; physical findings; laboratory findings; x-rays; other diagnostically helpful findings; course; pathology; and up to ten references to the biomedical literature, with an emphasis on review articles wherever possible. A small sample of nine disease entries

Sue London


FIGURE 6 DXplain Disease List

FIGURE 7 DXplain Explanation of Disease Screen Discussion oldisease HIATUS HERNIA (DIAPHRAGMATIC HERNIA). The tollowlng findings very strongly support thls disease: HEARTBURN The rollowing liudings strongly support lhis disease:

CHRONIC COUGH P 4 WEEKS. NORMAL CXRL The following findings support this diarase:

DYSPHAGIA The toUowing clinical n~anitestations(if present) would also support this disease: ERUCTATION

p EPIGASTRIC ABDOMINAL PAIN POSITIONAL

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FIGURE 8 DXplain Disease Information Screen

-.--- -----.---ETIOUXY----Due to circumstancesalTecting intra-abdominalpressure; sudden, severe weight loss or gain; pregnancy; ascites; ovarian tumor or other intra-abdominaltumor; kyphoscoliosis; loss of tissue elasticity; !nay be congenilal. -. ASSOCIATED TERMS AND CONDITIONS---------USUALLY: hernia, diaphragmatic SOMETIMES: elderly; male; esophagealdilation RARELY: pregnancy SYMPTOM& USUALLY: heartburn; relieved with silting uprigh~;relieved with food; relieved with antacids; nocturnal. SOMETIMES: epigastric abdominal pain; chest pain; positional; worse supine; emctation; chronic cough (>4 weeks, normal err): abdominal fullness sensation: abdominal pain; back pain. RARELY: dysphagia; vomiting; throat burning sensation. ADDITIONAL NOTES: Hiatal hernia; asymptomalic; variable; pressure symptoms as lightness, bloating, fullness; pnin or discomfort radiating to back, upper chest, len shoulder, arm; rclief of symptoms occurring in upright posture. Paraesophagealhernia: reflux symptoms absent; feel in^ of fullness, discomfort f l e r eating; bleedingcaused by lraunla of stomach in contact with esophageal hiatus. --PHYSICAL PINDINCSSOMETIMES: obesity; epigastric abdominal tenderness; gastrointestinalbleeding; hematen~esis;melena; abdominal tenderness. RARELY: abdominal dislension ADDITIONAL NOTES: Physical exam o f no value in esophageal hiatal hernia; peristaltic gurgling in large hernias. -----LABORATORY QINDINCSSOMETLMES: positive a~cultstool blood test. RARUY: anemia, mild or moderate; anemia ADDITIONAL NOTES: Endoscopic exam recognizing hypotonicity of gastrosopl~ageal junction; manometry helpful in recording esophageal intraluminal pressures.


-----

-

------

(displayl~ncated)

averaged 9.6 references per entry, ranging in publication year from 1971 to 1996, with the majority in the mid-1980s and early 1990s. The beginning o f the somewhat lengthy entry for "Hiatus Hernia" i s shown in Figure 8.

CONCLUSZON Not all diseases are included, nor does DXplain take into account preexisting conditions or the chronological sequence o f clinical


Sue London

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manifestations. Despite these limitations, it is a useful educational tool, particularly for problem-based learning (PBL) cases and for medical students in'clinical rotations, as it fills a niche not adequately covered by MEDLINE or medical texts. When IU medical students were informally asked by the Library for their opinions at the end of the trial period, several upper-classmen strongly recommended making DXplain access available on an ongoing basis, commenting on its usefulness and that they had been looking for such a tool for a long time. Based on these comments and usage statistics, Dxplain access has been added to the RLML electronic collection. With a small investment of time, and no enduser training or maintenance, the Library has been able to provide a popular student resource and enhance its image as a partner in medical education. ACCEPTED FOR PUBLICATION: AUGUST 1997 REFERENCES I. DXplain". Boston, MA: Laboratory of Computer Science, Massachusctts General Hospital. 1987. Available URL: http:Nlcs-dxplain.mgh.harvard.edu/ Icshome/dxplain.htm (Current as of April 29, 1997). 2. Barnett, G. Octo; Cimino, James J.; Hupp, Jon A.; and Hoffer, Edward P. "DXplain: An Evolving Diagnostic Decision Support System." JAMA 258 (July 3, 1987): 67-74. 3. Lowe, Henry J.; Lomax, Edward C.; and Polonkey, Stacey E. "The World Wide Web: A Review of an Emerging Internet-Based Technology for the Distribution of Biomedical Information." Journal of the American Medical lrfiratatics Association 3 (JanuarylFebruary 1996): 1-14. 4. Marshall, Joanna G.; Fitzgerald, Dorothy; and Busby, Lorraine et al. "A Study of Library Use in Problem-based and Traditional Medical Curricula." B d letin of the Medical Libra~yAssociation 81 (July 1993): 299-305. 5. West, Scott A. "Medical Education and the Role of Computers-as Seen Through the Eyes of a Medical Student." Jour.rral of Medical System 13 (October 1989): 237-4 1. 6. Hamilton, Rob.ert A. "FDA Examining Computer Diagnosis." FDA Consurner Magazine 29 (Septembcr 1995). Available URL:http:llwww.fda.govlfdacl featuresl795-compdiag.html (Current as of April 30, 1997). 7. Miller, Randolf A. "Evaluating Evaluations of Mcdical Diagnostic Systems." Journal of the American Medical I~formaticsAssocialion 3 (November1 December 1996): 429-3 1.


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8. Bemer, Eta S.; Jackson, James R.; and Algina, James. "Relationships Among Performance Scores of Four Diagnostic Decision Support Systems." Journal of the Anlerican Medical Informatics Associalion 3 (MayIJune 1996): 208-15. 9. Bankowitz, Richard A,; McNeil, Melissa A.; and Challinor, Sue M. et al. "Effect of a Computer-Assisted General Medicine Diagnostic Consultation Service on House Staff Diagnostic Strategy." Methods of lnfomalion in Medicine 28 (November 1989): 352-6. 10. Lincoln, Michael J.; Tumer, Charles W.; and Haug, Peter J. et al. "Iliad Training Enhances Medical Students' Diagnostic Skills." Journal of Medical Systems IS (February 1991): 93-1 10. I I. Crum, Cyril M.; Miller, Judith G.; and Wolf, Fredric M. "Computer-Based Problem Solving for Primary Care Diagnosis in an Internal Medicine Clerkship." Academic Medicine 69 (May 1994): 429-30.