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M A Musen

Publications and source records attributed to M A Musen.

At least 55 records · Page 3Linked to original sources
PubMed1996

Knowledge acquisition for temporal abstraction.

Temporal abstraction is the task of detecting relevant patterns in data over time. The knowledge-based temporal-abstraction method uses knowledge about a clinical domain's contexts, external events, and parameters to create meaningful interval-based abstractions from raw time-stamped clinical data. In this paper, we describe the acquisition and maintenance of domain-specific temporal-abstraction knowledge. Using the PROTEGE-II framework, we have designed a graphical tool for acquiring temporal knowledge directly from expert physicians, maintaining the knowledge in a sharable form, and converting the knowledge into a suitable format for use by an appropriate problem-solving method. In initial tests, the tool offered significant gains in our ability to rapidly acquire temporal knowledge and to use that knowledge to perform automated temporal reasoning.

Artificial Intelligence↗
PubMed1996

The EON model of intervention protocols and guidelines.

We present a computational model of treatment protocols abstracted from implemented systems that we have developed previously. In our framework, a protocol is modeled as a hierarchical plan where high-level protocol steps are decomposed into descriptions of more specific actions. The clinical algorithms embodied in a protocol are represented by procedures that encode the sequencing, looping, and synchronization of protocol steps. The representation allows concurrent and optional protocol steps. We define the semantics of a procedure in terms of an execution model that specifies how the procedure should be interpreted. We show that the model can be applied to an asthma guideline different from the protocols for which the model was originally constructed.

Adult↗
PubMed1996

Making generic guidelines site-specific.

Health care providers are more likely to follow a clinical guideline if the guideline's recommendations are consistent with the way in which their organization does its work. Unfortunately, developing guidelines that are specific to an organization is expensive, and limits the ability to share guidelines among different institutions. We describe a methodology that separates the site-independent information of guidelines from site-specific information, and that facilitates the development of site-specific guidelines from generic guidelines. We have used this methodology in a prototype system that assists developers in creating generic guidelines that are sharable across different sites. When combined with site information, generic guidelines can be used to generate site-specific guidelines that are responsive to organizational change and that can be implemented at a level of detail that makes site-specific computer-based workflow management and simulation possible.

Artificial Intelligence↗
PubMed1995

Computer-based screening of patients with HIV/AIDS for clinical-trial eligibility.

OBJECTIVE: To assess the potential effect of a computer-based system on accrual to clinical trials, we have developed methodology to identify retrospectively and prospectively patients who are eligible or potentially eligible for protocols. DESIGN: Retrospective chart abstraction with computer screening of data for potential protocol eligibility. SETTING: A county-operated clinic serving human immunodeficiency virus (HIV) positive patients with or without acquired immune deficiency syndrome (AIDS). PATIENTS: A randomly selected group of 60 patients who were HIV-infected, 30 of whom had an AIDS-defining diagnosis. DESIGN: Using a computer-based eligibility screening system, for each clinic visit and hospitalization, patients were categorized as eligible, potentially eligible, or ineligible for each of the 17 protocols active during the 7-month study period. Reasons for ineligibility were categorized. RESULTS: None of the patients was enrolled on a clinical trial during the 7-month period. Thirteen patients were identified as eligible for protocol; three patients were eligible for two different protocols; and one patient was eligible for the same protocol during two different time intervals. Fifty-four patients were identified as potentially eligible for a total of 165 accrual opportunities, but important information, such as the result of a required laboratory test, was missing, so that eligibility could not be determined unequivocally. Ineligibility for protocol was determined in 414 (35%) potential opportunities based only on conditions that were amenable to modification, such as the use of concurrent medications; 194 (17%) failed only laboratory tests or subjective determinations not routinely performed; and 346 (29%) failed only routine laboratory tests. CONCLUSIONS: There are substantial numbers of eligible and potentially eligible patients who are not enrolled or evaluated for enrollment in prospective clinical trials. Computer-based eligibility screening when coupled with a computer-based medical record offers the potential to identify patients eligible or potentially eligible for clinical trial, to assist in the selection of protocol eligibility criteria, and to make accrual estimates.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Ontology-based configuration of problem-solving methods and generation of knowledge-acquisition tools: application of PROTEGE-II to protocol-based decision support.

PROTEGE-II is a suite of tools and a methodology for building knowledge-based systems and domain-specific knowledge-acquisition tools. In this paper, we show how PROTEGE-II can be applied to the task of providing protocol-based decision support in the domain of treating HIV-infected patients. To apply PROTEGE-II, (1) we construct a decomposable problem-solving method called episodic skeletal-plan refinement, (2) we build an application ontology that consists of the terms and relations in the domain, and of method-specific distinctions not already captured in the domain terms, and (3) we specify mapping relations that link terms from the application ontology to the domain-independent terms used in the problem-solving method. From the application ontology, we automatically generate a domain-specific knowledge-acquisition tool that is custom-tailored for the application. The knowledge-acquisition tool is used for the creation and maintenance of domain knowledge used by the problem-solving method. The general goal of the PROTEGE-II approach is to produce systems and components that are reusable and easily maintained. This is the rationale for constructing ontologies and problem-solving methods that can be composed from a set of smaller-grained methods and mechanisms. This is also why we tightly couple the knowledge-acquisition tools to the application ontology that specifies the domain terms used in the problem-solving systems. Although our evaluation is still preliminary, for the application task of providing protocol-based decision support, we show that these goals of reusability and easy maintenance can be achieved. We discuss design decisions and the tradeoffs that have to be made in the development of the system.

Artificial Intelligence↗
PubMed1995

Support for information management in critical care: a new approach to identify needs.

Managing information is necessary to support clinical decision making and action in critical care. By understanding the nature of information management and its relationship to sound clinical practice, we should come to use technology more wisely. We demonstrated that a new approach inspired by ethnographic research methods could identify useful and unexpected findings about clinical information management. In this approach, a clinician experienced in a specific domain (critical care), with advice from a medical anthropologist, made short-term observations of information management in that domain. We identified 8 areas in a critical care Unit in which information management was seriously in need of better support. We also found interesting differences in how these needs were viewed by nurses and physicians. Our interest in this approach was at two levels: 1. Identify and describe representative instances of sub-optimal information management in a critical care Unit. 2. Investigate the effectiveness of such short-term observations by clinicians. Our long-range goal is to explore the use of this approach and the information it reveals to optimize the process of developing and selecting new information support tools, preparing for their introduction, and optimizing clinical outcomes.

Critical Care↗
PubMed1995

A web-based architecture for a medical vocabulary server.

For health care providers to share computing resources and medical application programs across different sites, those applications must share a common medical vocabulary. To construct a common vocabulary, researchers must have an architecture that supports collaborative, networked development. In this paper, we present a web-based server architecture for the collaborative development of a medical vocabulary: a system that provides network services in support of medical applications that need a common, controlled medical terminology. The server supports vocabulary browsing and editing and can respond to direct programmatic queries about vocabulary terms. We have tested the programmatic query-response capability of the vocabulary server with a medical application that determines when patients who have HIV infection may be eligible for certain clinical trials. Our emphasis in this paper is not on the content of the vocabulary, but rather on the communication protocol and the tools that enable collaborative improvement of the vocabulary by any network-connected user.

Computer Communication Networks↗
PubMed1995

A rational reconstruction of INTERNIST-I using PROTEGE-II.

PROTEGE-II is a methodology and a suite of tools that allow developers to build and maintain knowledge-based systems in a principled manner. We used PROTEGE-II to reconstruct the well-known INTERNIST-I system, demonstrating the role of a domain ontology (a framework for specification of a model of an application area), a reusable problem-solving method, and declarative mapping relations in creating a new, working program. PROTEGE-II generates automatically a domain-specific knowledge-acquisition tool, which, in the case of the INTERNIST-I reconstruction, has much of the functionality of the QMR-KAT knowledge-acquisition tool. This study provides a means to understand better both the PROTEGE-II methodology and the models that underlie INTERNIST-I.

Artificial Intelligence↗
PubMed1995

A comparison of the temporal expressiveness of three database query methods.

Time is a multifaceted phenomenon that developers of clinical decision-support systems can model at various levels of complexity. An unresolved issue for the design of clinical databases is whether the underlying data model should support interval semantics. In this paper, we examine whether interval-based operations are required for querying protocol-based conditions. We report on an analysis of a set of 256 eligibility criteria that the T-HELPER system uses to screen patients for enrollment in eight clinical-trial protocols for HIV disease. We consider three data-manipulation methods for temporal querying: the consensus query representation Arden Syntax, the commercial standard query language SQL, and the temporal query language TimeLineSQL (TLSQL). We compare the ability of these three query methods to express the eligibility criteria. Seventy nine percent of the 256 criteria require operations on time stamps. These temporal conditions comprise four distinct patterns, two of which use interval-based data. Our analysis indicates that the Arden Syntax can query the two non-interval patterns, which represent 54% of the temporal conditions. Timepoint comparisons formulated in SQL can instantiate the two non-interval patterns and one interval pattern, which encompass 96% of the temporal conditions. TLSQL, which supports an interval-based model of time, can express all four types of temporal patterns. Our results demonstrate that the T-HELPER system requires simple temporal operations for most protocol-based queries. Of the three approaches tested, TLSQL is the only query method that is sufficiently expressive for the temporal conditions in this system.

Decision Making, Computer-Assisted↗
PubMed1995

A comparison of two computer-based prognostic systems for AIDS.

We compare the performances of a Cox model and a neural network model that are used as prognostic tools for a cohort of people living with AIDS. We modeled disease progression for patients who had AIDS (according to the 1993 CDC definition) in a cohort of 588 patients in California, using data from the ATHOS project. We divided the study population into 10 training and 10 test sets and evaluated the prognostic accuracy of a Cox proportional hazards model and of a neural network model by determining the number of predicted deaths, the sensitivities, specificities, positive predictive values, and negative predictive values for intervals of one year following the diagnosis of AIDS. For the Cox model, we further tested the agreement between a series of binary observations, representing death in one, two, and three years, and a set of estimates which define the probability of survival for those intervals. Both models were able to provide accurate numbers on how many patients were likely to die at each interval, and reasonable individualized estimates for the two- and three-year survival of a given patient, but failed to provide reliable predictions for the first year after diagnosis. There was no evidence that the Cox model performed better than did the neural network model or vice-versa, but the former method had the advantage of providing some insight on which variables were most influential for prognosis. Nevertheless, it is likely that the assumptions required by the Cox model may not be satisfied in all data sets, justifying the use of neural networks in certain cases.

Acquired Immunodeficiency Syndrome↗
PubMed1995

The development of a controlled medical terminology: identification, collaboration, and customization.

An increasing focus in health care is the development and use of electronic medical record systems to capture and store patient information. T-HELPER is an electronic medical record system that health care providers use to record ambulatory-care patient progress notes. These data are stored in an on-line database and analyzed by T-HELPER to provide users with decision support regarding patient eligibility for clinical trial protocols and assistance with continued protocol-based care. Our goal is to provide a system that enhances the process of identifying patients who are potentially eligible for clinical trials of experimental therapies in a clinic that is limited by the existence of a singular clinical trial coordinator. Effective implementation of such a system requires the development of a meaningful controlled medical terminology that satisfies the needs of a diverse community of providers all of who contribute to the health care process. The development of a controlled medical terminology is a process of identification, collaboration, and customization. We enlisted the help of collaborators familiar with the proposed work environment to identify user needs, to collaborate with our development team to construct the preliminary terminology, and to customize the controlled medical terminology to make it meaningful and acceptable to the clinic users.

Ambulatory Care↗
PubMed1995

PROTEGE-II: computer support for development of intelligent systems from libraries of components.

PROTEGE-II is a suite of tools that facilitates the development of intelligent systems. A tool called MAiTRE allows system builders to create and refine abstract models (ontologies) of application domains. A tool called DASH takes as input a modified domain ontology and generates automatically a knowledge-acquisition tool that application specialists can use to enter the detailed content knowledge required to define particular applications. The domain-dependent knowledge entered into the knowledge-acquisition tool is used by assemblies of domain-independent problem-solving methods that provide the computational strategies required to solve particular application tasks. The result is an architecture that offers a divide-and-conquer approach that separates system-building tasks that require skill in domain analysis and modeling from those that require simple entry of content knowledge. At the same time, applications can be constructed from libraries of component--of both domain ontologies and domain-independent problem-solving methods--allowing the reuse of knowledge and facilitating ongoing system maintenance. We have used PROTEGE-II to construct a number of knowledge-based systems, including the reasoning components of T-Helper, which assists physicians in the protocol-based care of patients who have HIV infection.

Clinical Trials as Topic↗
PubMed1995

Hierarchical neural networks for survival analysis.

Neural networks offer the potential of providing more accurate predictions of survival time than do traditional methods. Their use in medical applications has, however, been limited, especially when some data is censored or the frequency of events is low. To reduce the effect of these problems, we have developed a hierarchical architecture of neural networks that predicts survival in a stepwise manner. Predictions are made for the first time interval, then for the second, and so on. The system produces a survival estimate for patients at each interval, given relevant covariates, and is able to handle continuous and discrete variables, as well as censored data. We compared the hierarchical system of neural networks with a nonhierarchical system for a data set of 428 AIDS patients. The hierarchical model predicted survival more accurately than did the nonhierarchical (although both had low sensitivity). The hierarchical model could also learn the same patterns in less than half the time required by the nonhierarchical model. These results suggest that the use of hierarchical systems is advantageous when censored data is present, the number of events is small, and time-dependent variables are necessary.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Knowledge-based temporal abstraction in diabetes therapy.

We suggest a general framework for solving the task of creating abstract, interval-based concepts from time-stamped clinical data. We refer to this problem-solving framework as the knowledge-based temporal-abstraction (KBTA) method. The KBTA method emphasizes explicit representation, acquisition, maintenance, reuse, and the sharing of knowledge required for abstraction of time-oriented clinical data. We describe the subtasks into which the KBTA method decomposes its task, the problem-solving mechanisms that solve these subtasks, and the knowledge necessary for instantiating these mechanisms in a particular clinical domain. We have implemented the KBTA method in the RESUME system and have applied it to the task of monitoring the care of insulin-dependent diabetics.

Artificial Intelligence↗
PubMed1995

CALIPER: individualized-growth curves for the monitoring of children's growth.

Monitoring children's growth is a fundamental part of pediatric care. Deviation from the expected growth pattern can be an important sign of disease and often results in parental anxiety. Most preprinted growth curves are based on cross-sectional data derived from population-based studies of normal children. Since the age of the pubertal growth spurt varies substantially among the normal curves, these curves don't adequately reflect the expected growth pattern of an individual child. In addition, any preprinted growth curve based on the general population becomes less useful when the maturation of a child and the heights of it's parents differ substantially from the average. Established methods exist to adjust the general reference-growth curves for parental height. However, these methods generally are too time consuming to be used in clinic. Only heuristic methods are known to us to adjust the general-reference curves for maturation. We have developed the decision-support system CALIPER, that enables and standardizes the generation of individualized reference-growth curves. CALIPER consists of a graphical interface for data entry, a progress-report generator, and a module for the interactive, dynamic display of general-reference curves and individualized-reference curves. Preference settings such as ethnic background and gender determine the required population curves and individualization method. Individualization can be based on parental height and/or maturation. Maturation is based on an assessment of a child's bone age and/or pubertal stage. The bone age can be assessed by different methods. We have performed an evaluation of CALIPER's methodology by assessing the effect of individualization on the reference growth curves for 466 normally growing children. The individualized-reference curves reflect the growth pattern of children significantly better than the general-reference curves. CALIPER can be used on a case by case base as an aid in clinic (assessment of children's growth and communication with patient and parents) or as a tool to investigate current clinical questions concerning the relation of bone age, pubertal stage, and growth pattern for any part of the population. Besides providing for decision support by the interactive graphical representation of individualized-reference curves and growth data, CALIPER will be linked to a module that can provide automatic interpretation of the data (Kuilboer et al, SCAMC-93). CALIPER runs on a Macintosh, and requires 600K of memory. A color monitor is preferable, but not required. We will demonstrate several cases that will illustrate the clinical problem and CALIPER's potential.

Body Height↗
PubMed1995

The separation of reviewing knowledge from medical knowledge.

The developers of reviewing systems that rely on computer-based patient-record systems as a source of data need to model reviewing knowledge and medical knowledge. We simulate how the same medical knowledge could be entered in four different systems: CARE, the Arden syntax, Essential-attending and HyperCritic. We subsequently analyze how the original knowledge is represented in the symbols or syntax used by these systems. We conclude that these systems provide different alternatives in dealing with the vocabulary provided by the computer-based patient records. In addition, the use of computer-based patient records for review poses new challenges for the content of that record: to facilitate review, the reasoning of the physician needs to be captured in addition to the actions of the physician.

Artificial Intelligence↗
PubMed1995

Development of a controlled medical terminology: knowledge acquisition and knowledge representation.

The creation of controlled medical terminologies is a central challenge in the development of electronic patient records. In the T-Helper patient-record system, designed for the care of patients with HIV disease, the IVORY module allows health-care workers to compose textual progress notes by making selections from menus generated automatically from a controlled medical terminology. Construction of this IVORY terminology required extensive design sessions with a team of computer scientists and an expert physician. Refinement of the terminology was only possible when the design team could envision how the completed T-Helper system would be used in the context of clinical practice. Development of controlled medical terminologies is a significant problem in knowledge acquisition. Techniques used to acquire and represent clinical concepts for the purpose of building decision-support systems also are appropriate for the construction of controlled terminologies such as the one in T-Helper.

Artificial Intelligence↗