Biomedical subjects

D R Blewett

Publications and source records attributed to D R Blewett.

7 recordsLinked to original sources

PubMed1992

Prevalence and incidence of viral hepatitis in health workers in the prehepatitis B vaccination era.

To assess the impact of hepatitis B virus on health workers, the authors studied baseline prevalences of hepatitis B serologic markers and undertook prospective surveillance to assess hepatitis B attack rates in 837 health workers and 994 blood-donor controls between 1977 and 1982, before the introduction of hepatitis B vaccine. The baseline prevalence of all hepatitis B markers was 14% in health workers and 6% in controls (p < 0.001); exposure to hepatitis B virus was related to the intensity of blood exposure and its duration. In contrast, the frequency of exposure to hepatitis A virus, a nonblood-borne agent, was lower in health workers (11%) than in controls (16%) (p < 0.01) and increased as a function of age. Multivariate logistic regression analysis identified occupational categories with frequent blood contact, rather than duration of exposure, as being the dominant variable for exposure to hepatitis B virus; for hepatitis A virus exposure, age was the most significant variable. Among health workers susceptible to hepatitis B, the incidence of new definite hepatitis B infections was 1.0% per year in 362 health workers (804 person-years of follow-up observation) with frequent blood contact versus 0% per year in 258 health workers (534 person-years of observation) with limited blood contact (p = 0.017). For definite plus probable cases combined, the incidence of new hepatitis B infections was 1.5% per year versus 0.2% per year for the groups with frequent and limited blood exposures, respectively (p = 0.0013). There were no new cases of hepatitis A or B or seroconversions in controls and only one case of hepatitis A acquired outside the hospital by a health worker. These data confirm the high prevalence of hepatitis B exposure and document in a prospective study the high incidence over time of new hepatitis B virus infections in health workers unprotected by vaccination. Such findings reiterate the need for aggressive vaccination programs in health workers exposed to blood.

Hepatitis A Antibodies↗

PubMed1992

The effect of aspirin on the risk of stroke in patients with nonrheumatic atrial fibrillation: The BAATAF Study.

Recent randomized trials have consistently demonstrated the marked efficacy of warfarin in reducing the risk of stroke caused by nonrheumatic atrial fibrillation. These trials have provided conflicting evidence on the effect of aspirin. We report the aspirin analysis from the BAATAF study, a trial in which control patients could choose to take aspirin. There we two strokes in 446 person-years with warfarin (annual rate of 0.45%); eight strokes in 206 person-years with aspirin, most at 325 mg per day (annual rate of 3.9%); and five strokes in 271 person-years among patients taking neither aspirin nor warfarin (annual rate of 1.8%). Simultaneously controlling for the other significant determinants of stroke in the BAATAF study (age, mitral annular calcification, and clinical heart disease), the relative rates (95% confidence interval) of stroke were: (1) warfarin/aspirin = 0.135 (0.029 to 0.64); (2) aspirin/(no aspirin and no warfarin) = 1.95 (0.64 to 5.97); and (3) warfarin/(no aspirin and no warfarin) = 0.263 (0.051 to 1.36). Our "treatment received" analysis argues that warfarin is strikingly more effective than aspirin in preventing stroke in nonrheumatic atrial fibrillation.

Aged↗

PubMed1992

Representation of nursing terminology in the UMLS Metathesaurus: a pilot study.

To see whether the National Library of Medicine's Metathesaurus (tm) includes terminology relevant to clinical nursing practice, two widely used nursing vocabularies were matched against the Meta. The two nursing vocabularies are 1) the North American Nursing Diagnosis List of Approved Diagnoses; and 2) the Omaha System, a vocabulary of problems and interventions developed by the Omaha Visiting Nurses Association. First, the terms were scanned against Meta in their "native" form, with phrases and combinations intact. This produced a relatively low percentage of exact matches (12%). Next, the terms were separated into "core concepts" and "modifiers" and the analysis was repeated. The percentage of exact matches to terms in Meta increased to 32%. However, the semantic types of the split terms often were not equivalent to the semantic types of the phrases from which the split terms were derived; also, in some cases, terms returned as exact matches had different meanings in Meta. Automatic scanning for lexical matches is a helpful first step in searching for vocabulary representation in Meta, but term-by-term search for context, semantic type and definition is essential. However, it seems clear that representation of nursing terminology in the Metathesaurus needs to be expanded.

Nursing↗

PubMed1992

Q & A: a query formulation assistant.

Inexperienced users of online medical databases often do not know how to formulate their queries for effective searches. Previous attempts to help them have provided some standard procedures for query formulation, but depend on the user to enter the concepts of a query properly so that the correct search strategy will be formed. Intelligent assistance specific to a particular query often is not given. Several systems do refine the initial strategy based on relevance feedback, but usually do not make an effort to determine how well-formed a query is before actually performing the search. As part of the Interactive Query Workstation (IQW), we have developed an expert system, Questions and Answers (Q&A), that assists in formulating an initial strategy given concepts entered by the user and that determines if the strategy is well-formed, refining it when necessary.

Expert Systems↗

PubMed1992

Interactive query workstation: a demonstration of the practical use of UMLS knowledge sources.

The Interactive Query Workstation (IQW) has been developed to provide clinicians with a uniform program interface for retrieving medical-related information from various computer-based information resources. These resources can vary in content (bibliographic databases, drug information, general medical text databases), function (article retrieval, differential diagnosis, drug interaction detection, or drug dosage and administration information), and media formats (local hard disk, CD-ROM, local area network, or distant telecommunication link). IQW allows modular addition of new resources as well as extension of previously installed resources. The National Library of Medicine's three Unified Medical Language System (UMLS) Knowledge Sources, the Metathesaurus (Meta), the Semantic Network, and the Information Sources Map (ISM) have been incorporated into many aspects of IQW. Meta provides information about medical terminology and aids IQW in isolating the basic concepts from a clinician's question. The Semantic Network provides information about the categorization of concepts and possible relations between concepts. It also assists IQW in determining which queries are appropriate for a set of concepts contained in the clinician's question. The ISM provides information about the content available from a computer-based resources and aids IQW in selecting an appropriate resource from which to collect information. The computer-based resource selection is performed without user intervention. This interactive demonstration shows an environment which increases the accessibility of medical information to clinicians by utilizing the three UMLS Knowledge Sources.

Information Storage and Retrieval↗

PubMed1991

Interactive Query Workstation: standardizing access to computer-based medical resources.

Methods of using multiple computer-based medical resources efficiently have previously required either the user to manage the choice of resource and terms, or specialized programming. Standardized descriptions of what resources can do and how they may be accessed would allow the creation of an interface for multiple resources. This interface would assist a user in formulating queries, accessing the resources and managing the results. This paper describes a working prototype, the Interactive Query Workstation (IQW). The IQW allows users to query multiple resources: a medical knowledge base (DXplain), a clinical database (COSTAR/MQL), a bibliographic database (MEDLINE), a cancer database (PDQ), and a drug interaction database (PDR). Descriptions of each resource were developed to allow IQW to access these resources. The descriptions are composed of information on how data are sent and received from a resource, information on types of query to which a resource can respond, and information on what types of information are needed to execute a query. These components form the basis of a standard description of resources.

Artificial Intelligence↗

PubMed1991

Casebook: a system for tracking clinical encounters.

Casebook is a clinically oriented database, written in MUMPS, and designed for recording the clinical encounters of medical students at Harvard Medical School. Its main goals are to 1) increase student use of computer technology, 2) help faculty evaluate the diversity of clinical experiences on their service, 3) provide data to the faculty on the "typical" experience of medical students on their service to aid in the evaluation of the curriculum and, 4) provide report-generation capabilities for the students to improve dialog with their preceptors. Students are able to enter information on "Problems" and "Procedures" selecting from a pop-up menu of medical terms or by entering free text. Casebook is currently in use in the Medicine, OB/GYN, Pediatric and Ambulatory rotations. At sites where the faculty take an active interest in the use of Casebook students perceive it to be valuable and subsequently use it more frequently. It is currently being expanded for use by medical students in their second, third, and fourth years of school.

Attitude to Computers↗