M M Wagner

University of Pittsburgh, Pittsburgh, PA, United States

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Publications (22)9.27 Total impact

  • Wagner MM, Espino JU, Tsui F-C, Aryel RM
    05/2004: pages 513-531; , ISBN: 0-387-40805-3
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    ABSTRACT: A surge of development of new public health surveillance systems designed to provide more timely detection of outbreaks suggests that public health has a new requirement: extreme timeliness of detection. The authors review previous work relevant to measuring timeliness and to defining timeliness requirements. Using signal detection theory and decision theory, the authors identify strategies to improve timeliness of detection and position ongoing system development within that framework.
    Journal of public health management and practice: JPHMP 12/2001; 7(6):51-9. · 0.96 Impact Factor
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    J U Espino, M M Wagner
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    ABSTRACT: ICD-9-coded chief complaints and diagnoses are a routinely collected source of data with potential for use in public health surveillance. We constructed two detectors of acute respiratory illness: one based on ICD-9-coded chief complaints and one based on ICD-9-coded diagnoses. We measured the classification performance of these detectors against the human classification of cases based on review of emergency department reports. Using ICD-9-coded chief complaints, the sensitivity of detection of acute respiratory illness was 0.44 and its specificity was 0.97. The sensitivity and specificity using ICD-9-coded diagnoses were no different. These properties of excellent specificity and moderate sensitivity, coupled with the earliness and electronic availability of such data, support the use of detectors based on ICD-9 coding of emergency department chief complaints in public health surveillance.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/2001;
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    F C Tsui, M M Wagner, V Dato, C C Chang
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    ABSTRACT: To assess the value of ICD-9 coded chief complaints for early detection of epidemics, we measured sensitivity, positive predictive value, and timeliness of Influenza detection using a respiratory set (RS) of ICD-9 codes and an Influenza set (IS). We also measured inherent timeliness of these data using the cross-correlation function. We found that, for a one-year period, the detectors had sensitivity of 100% (1/1 epidemic) and positive predictive values of 50% (1/2) for RS and 25% (1/4) for IS. The timeliness of detection using ICD-9 coded chief complaints was one week earlier than the detection using Pneumonia and Influenza deaths (the gold standard). The inherent timeliness of ICD-9 data measured by the cross-correlation function was two weeks earlier than the gold standard.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/2001;
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    M M Wagner, F C Tsui, J Pike, L Pike
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    ABSTRACT: We describe the requirements and design of an enterprise-wide notification system. From published descriptions of notification schemes, our own experience, and use cases provided by diverse users in our institution, we developed a set of functional requirements. The resulting design supports multiple communication channels, third party mappings (algorithms) from message to recipient and/or channel of delivery, and escalation algorithms. A requirement for multiple message formats is addressed by a document specification. We implemented this system in Java as a CORBA object. This paper describes the design and current implementation of our notification system.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/1999;
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    W R Hogan, M M Wagner
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    ABSTRACT: Clinical event monitors (CEMs) seek to improve patient care and reduce its cost by prompting clinicians to take actions that have these effects. To persuade clinicians to act, CEMs have used prewritten-text explanations. However, we encountered limitations of prewritten-text explanations in our CEM. Therefore, we decided to implement an advanced method for explanation (Suermondt's method for belief-network explanation). This method is promising, but whether it is generally applicable to all of clinical event monitoring and whether it is as efficacious as prewritten-text explanations remain areas for future research.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/1999;
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    ABSTRACT: We developed and evaluated a feature that allows users to control what types of clinical information are delivered to them. Using a paper or web-based configuration form, users turn individual alerts and sets of results on or off, and set how they are delivered. We used usage rates to evaluate this feature. Of 16 residents who had received clinical information from our clinical event monitor, 4 (25%) made at least one change (range 10-25). Of 41 interns, 5 (12.2%) made at least one change (range 5-91). The difference was borderline significant (p < 0.1). 5/7 web users changed preferences through a dial-up connection from home. More users used the web-based preference form than the paper form. This difference may be due to the better accessibility of the web-based form. A survey established that this feature was not as highly utilized as anticipated partly because the initial (default) preference setting was acceptable and partly because the users were too busy to customize their alert settings. We conclude that user configuration of a system that delivers information using a web-based preference form is feasible and may become important as the volume of information and number of available communication channels increase.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 01/1999;
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    W R Hogan, M M Wagner
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    ABSTRACT: We argue that the optimal use of communication channels in clinical event monitors is an important design consideration for these systems. We review the state-of-the-art in selection of communication channels, including our current approach--allowing users to choose the communication channel by which the event monitor sends each notification. We describe a new approach that we are in the process of developing. In this new approach, we view event monitoring as the decision of whether and how to send new patient data to a clinician and apply the principle of maximum expected utility to this decision problem. Our initial experience with this approach suggests that notifying clinicians of normal patient data may be of high utility. We also found that methods for explanation in uncertain reasoning may be necessary in this approach.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/1998;
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    ABSTRACT: The ability to have access to information relevant to patient care is essential within the healthcare environment. To meet the information needs of its workers, healthcare information systems must fulfill a variety of functional requirements. One of these requirements is to define how workers will interact with the system to gain the information they need. Currently, most healthcare information systems rely on users querying the system via a fixed terminal for the information they desire; a method that is inefficient because there is no guarantee the information will be available at the time of their query and it interrupts their work flow. In general, clinical event monitors--systems whose efficacy relies on the delivery of time-critical information--have used e-mail and numeric pagers as their methods to deliver information. Each of these methods, however, still requires the user to perform additional steps, i.e., log into an information system in order to attain the information about which the system is alerting them. In this paper we describe the integration and use of 2-way alphanumeric pagers in CLEM, the UPMC Health System's Clinical Event Monitor, and how the use of these pagers addresses the information needs of mobile workers in healthcare.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/1998;
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    ABSTRACT: We elicited from medical house staff their preferences for e-mail and alphanumeric pager as communication channels for the delivery of 18 different types of clinical information about their inpatients. For each type, we calculated the proportion of users who preferred delivery by e-mail, pager, both, or neither (usual delivery). For 14/18 (78%) types, more users preferred delivery by pager than by the other options. For 2/18 (11%) types, e-mail was preferred. For 2/18 (11%) types, more users preferred redundant delivery using both channels. For no types did more users prefer neither, meaning that the information would be delivered by traditional channels, if any. We conclude that medical house staff in the inpatient setting prefer to receive many types of clinical information by pager. The reason may be that they otherwise would have to query clinical information systems for these data, which is wasteful of their time and introduces delays into the process of care. Additionally, we found significant inter-user variability, suggesting that it may be useful for the notification services of an enterprise to employ user profiles for the delivery of clinical information.
    Proceedings / AMIA ... Annual Symposium. AMIA Symposium 02/1998;
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    ABSTRACT: The utilization of the appropriate level of temporal abstraction is an important aspect of time modeling. We discuss some aspects of the relation of temporal abstraction to important knowledge engineering parameters such as model correctness, ease of model specification, knowledge availability, query completeness, inference tractability, and semantic clarity. We propose that versatile and efficient time-modeling formalisms should encompass ways to represent and reason at more than one level of abstraction, and we discuss such a hybrid formalism. Although many research efforts have concentrated on the automation of specific temporal abstractions, much research needs to be done in understanding and developing provably optimal abstractions. We provide an initial framework for studying this problem in a manner that is independent of the particular problem domain and knowledge representation, and suggest several research challenges that appear worth pursuing.
    Computers in Biology and Medicine 10/1997; 27(5):411-34. · 1.16 Impact Factor
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    ABSTRACT: Although the literature on event monitoring is extensive, it does not cover all issues that we encountered while developing an event monitor at our institution. We had to resolve issues related to event detection, scalability, what topics were suitable for asynchronous decision support, and overlap of efforts of other groups at the institution attempting to improve quality and lower cost of care. In this paper, we describe our experience deploying CLEM, the clinical event monitor at the University of Pittsburgh with emphasis on these topics.
    Proceedings: a conference of the American Medical Informatics Association / ... AMIA Annual Fall Symposium. AMIA Fall Symposium 02/1997;
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    M C Pankaskie, M M Wagner
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    ABSTRACT: We developed a clinical event monitor that is currently deployed in an inpatient setting. We selected CLIPS as the basis for its KB and inference engine. This paper describes the considerations that went into that decision, how we represented drug and laboratory knowledge in CLIPSs, and how we extended CLIPS to deal with temporal inferences. We also review the published literature about the use of CLIPS in medicine.
    Proceedings: a conference of the American Medical Informatics Association / ... AMIA Annual Fall Symposium. AMIA Fall Symposium 02/1997;
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    W R Hogan, M M Wagner
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    ABSTRACT: Researchers have advocated the supplementation of coded fields with free-text fields in electronic medical records (EMRs) to provide clinicians with flexibility during data entry. They cite advantages of more complete data capture and improved clinician acceptance and use of the EMR. However, free text may have the disadvantage of changing the meaning of coded data, which causes lower data accuracy for applications that cannot read free text. We studied the free-text entries that clinicians made during the recording of medication data. We found that these entries changed the meaning of coded data and lowered data accuracy for the medical decision-support system (MDSS) in our EMR. We conclude that supplemental free-text entries made by clinicians frequently alter the meaning of coded data.
    Proceedings: a conference of the American Medical Informatics Association / ... AMIA Annual Fall Symposium. AMIA Fall Symposium 02/1996;
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    ABSTRACT: Improvement in the performance of reminder systems may be facilitated by the use of new representations. A decision-theoretic representation, for example, may enable a reminder system to represent and reason about the probabilities that a reminder will be a true or a false alarm and the relative utilities of these events. We extended a previously described decision-theoretic model to include such events. The model now represents explicitly the uncertainty, costs, and benefits of sending a reminder. We also extended the model to remove an assumption of reminder independence. As a step towards testing a hypothesis that this approach will support better performance than a rule-based approach, we analyzed a set of CARE rules and showed that our representation can represent these rules.
    Proceedings: a conference of the American Medical Informatics Association / ... AMIA Annual Fall Symposium. AMIA Fall Symposium 02/1996;
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    M M Wagner, W R Hogan
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    ABSTRACT: To measure the accuracy of medication records stored in the electronic medical record (EMR) of an outpatient geriatric center. The authors analyzed accuracy from the perspective of a clinician using the data and the perspective of a computer-based medical decision-support system (MDSS). Prospective cohort study. The EMR at the geriatric center captures medication data both directly from clinicians and indirectly using encounter forms and data-entry clerks. During a scheduled office visit for medical care, the treating clinician determined whether the medication records for the patient were an accurate representation of the medications that the patient was actually taking. Using the available sources of information (the patient, the patient's vials, any caregivers, and the medical chart), the clinician determined whether the recorded data were correct, whether any data were missing, and the type and cause for each discrepancy found. At the geriatric center, 83% of medication records represented correctly the compound. dose, and schedule of a current medication; 91% represented correctly the compound. 0.37 current medications were missing per patient. The principal cause of errors was the patient (36.1% of errors), who misreported a medication at a previous visit or changed (stopped, started, or dose-adjusted) a medication between visits. The second most frequent cause of errors was failure to capture changes to medications made by outside clinicians, accounting for 25.9% of errors. Transcription errors were a relatively ucommon cause (8.2% of errors). When the accuracy of records from the center was analyzed from the perspective of a MDSS, 90% were correct for compound identity and 1.38 medications were missing or uncoded per patient. The cause of the additional errors of omission was a free-text "comments" field-which it is assumed would be unreadable by current MDSS applications-that was used by clinicians in 18% of records to record the identity of the medication. Medication records in an outpatient EMR may have significant levels of data error. Based on an analysis of correctable causes of error, the authors conclude that the most effective extension to the EMR studied would be to expand its scope to include all clinicians who can potentially change medications. Even with EMR extensions, however, ineradicable error due to patients and data entry will remain. Several implications of ineradicable error for MDSSs are discussed. The provision of a free-text "comments" field increased the accuracy of medication lists for clinician users at the expense of accuracy for a MDSS.
    Journal of the American Medical Informatics Association 01/1996; 3(3):234-44. · 3.57 Impact Factor
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    W R Hogan, M M Wagner
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    ABSTRACT: Differences in data definition between sites are a known obstacle to sharing of reminder-system rule sets. We identify another data characteristic--data accuracy--with implications for sharing. We reviewed the literature on data accuracy and found reports of high error rates for many data classes used by reminder systems (e.g., problem lists). The accuracy of other, equally important, data classes had not been characterized. Wide variations in accuracy between sites has been observed, suggesting that such differences may pose a previously unrecognized barrier to sharing of reminder rules. We propose a belief-network model for encoding reminder rules that explicitly models site-specific data accuracy and we discuss how encoding knowledge in this format may lower the cost and effort required to share reminder rules between sites.
    Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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    M M Wagner, G F Cooper
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    ABSTRACT: PRETRIEVE is a belief-network-based, unsolicited information-retrieval system that performs machine learning based on user feedback. We report here on the document-ordering and document-retrieval performance of PRETRIEVE. We developed a test collection of 410 judgments of document utility in a simulated medical order-entry context. We characterized the validity of these judgments, which were elicited from domain experts, by measuring interrater and intrarater reproducibility. We developed a measure of the quality of document orderings similar to the ROC-curve analysis used to evaluate document-retrieval systems. We found that the ordering performance of the PRETRIEVE system was (1) substantially better than random, (2) somewhat less than ideal, and (3) superior to that of versions of the PRETRIEVE system that used relevance feedback instead of utility feedback. Under a set of assumptions, which we make explicit, we found that the documents retrieved by a version of PRETRIEVE that modeled time cost were of higher utility than those retrieved by a similar rule-based system.
    Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1995;
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    M M Wagner, G F Cooper
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    ABSTRACT: Reminder systems and clinical medical librarian services often provide information to clinicians without requiring that a clinician actively seek information. This characteristic may explain in part the effectiveness and high clinician acceptance of these systems. We term systems with this characteristic "information pretrieval systems" to distinguish them from information retrieval systems, which require a clinician to articulate an information need in the form of a query. Because of the increasing importance of information pretrieval systems in medical care, we have developed a decision-theoretic model of an ideal information pretrieval system. In this paper, we present this model and suggest its use as an analytic framework for understanding existing approaches, and as a formal basis for a functioning pretrieval system.
    Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1993;
  • M M Wagner, G F Cooper
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    ABSTRACT: This paper describes MetaIndex, an automatic indexing program that creates symbolic representations of documents for the purpose of document retrieval. MetaIndex uses a simple transition network parser to recognize a language that is derived from the set of main concepts in the Unified Medical Language System Metathesaurus (Meta-1). MetaIndex uses a hierarchy of medical concepts, also derived from Meta-1, to represent the content of documents. The goal of this approach is to improve document retrieval performance by better representation of documents. An evaluation method is described, and the performance of MetaIndex on the task of indexing the Slice of Life medical image collection is reported.
    Computers and Biomedical Research 09/1992; 25(4):336-50.