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Biomedical subjects

L A Lenert

Publications and source records attributed to L A Lenert.

At least 37 records · Page 2Linked to original sources
PubMed1997

Studying ulcerative colitis over the World Wide Web.

OBJECTIVES: The Internet may provide a cost-effective means to collect outcomes data needed to improve the quality and efficiency of medical care. We explored the feasibility and methodology of a longitudinal outcomes study of Internet users who have ulcerative colitis (UC). METHODS: We created an open-enrollment electronic survey of Internet users who have UC and recorded the number of respondents, their demographics, and their willingness to participate. RESULTS: In a 2-month period, 582 users browsed the survey, 172 (30%) completed the questionnaire, and 162 (95%) reported willingness to enroll this study. Eighty-three percent were willing to release their medical records to verify their diagnosis. Most (> 70%) had the same E-mail address over 2 yr, suggesting that long-term follow-up could be performed electronically. In comparison with the male predominance of Internet users, respondents had gender distribution similar to that of patients who have UC. In comparison with the general population, respondents have higher education and higher household income. CONCLUSIONS: The Internet community could serve as a resource for general population outcome studies. Selection bias due to limited availability and use of the networked computers may affect results. The Internet community, however, is expanding rapidly, so it should become more representative of the general population.

Adult↗
PubMed1997

Willingness-to-pay utility assessment: feasibility of use in normative patient decision support systems.

The authors developed an automated patient interviewing tool to elicit individuals' willingness-to-pay (WTP) utilities under conditions of uncertainty and examined the reliability of this method and its potential usefulness in clinical decision support. We tested this method in 52 healthy volunteers using a computer-based interview that trained subjects in standard gamble (SG) and WTP methods, and elicited preferences for moderate Gaucher disease using WTP and SG. We assessed the validity of the WTP method by calculating the cost-effectiveness threshold implied by subjects' WTP and SG utilities; we also assessed subjects' understanding and comfort with using WTP for decision making by a questionnaire. The WTP method had good test-retest reliability (r = 0.796), and produced a cost-effectiveness ratio and ratings for understanding and clarity that support its validity. Moreover, many subjects felt that WTP was a reasonable (83%) method for therapeutic decision making and expressed comfort (62%) in using the method for their own health care decisions. These results suggest that a probabilistic method for WTP utility assessment is potentially useful for acquiring patient preferences for use in normative decision support systems.

Adult↗
PubMed1997

SecondOpinion: interactive Web-based access to a decision model.

In this paper, we describe a computer architecture, which we call SecondOpinion, designed for automated, normative patient decision support over the World Wide Web. SecondOpinion custom tailors the discussion of therapy options for patients by eliciting their preferences for relevant health states via an interactive WWW interface and then integrating those results in a decision model. The SecondOpinion architecture uses a Finite State Machine representation to track the course of a patient's consultation and to choose the next action to take. The consultation has five distinct types of interactions: explanation of health states, assessment of preferences, detection and correction of errors in preference elicitations, and feedback on the implications of preference. A linear "summary model" speeds calculations of predictions from the decision model and makes it possible to dynamically calculate 95% confidence intervals for the marginal utility of each treatment option. Preferences for states are assessed in the order of their variance contribution to the models predictions in an iterative fashion. Only the states required to obtain a 95% Confidence Interval (CI) that excludes zero are assessed. In Monte Carlo simulation studies, the average number of utility assessments required for the 95% CI to exclude zero in an individual was 4.24 (SD = 1.97) out of 8 relevant health states. the SecondOpinion architecture provides an efficient, "discussion-like" experience leading to an individual-specific treatment recommendation. It may be a cost-effective approach to bring decision analytic advice to the bedside.

Computer Communication Networks↗
PubMed1996

Computer-assisted quality of life assessment for clinical trials.

A patient's quality of life is difficult to assess. Most methods designed to evaluate quality of life for clinical trials are time consuming, subject to varied interpretation among patients and assessors, and apply scales with only a limited relationship to utility theory. We have developed a HyperCard program, incorporating animated graphics, to (1) improve the speed of collection and collation of data, (2) improve understanding between patients and assessors, and (3) incorporate utility theory-based assessments. We assessed the quality of life of 25 patients with end-stage renal disease receiving hemodialysis using a traditional paper-based presentation and, eight months later, repeated the assessment with a computer-assisted presentation. Each presentation incorporated five techniques for evaluating quality of life: the Campbell Index of Well-being, the Kaplan-Bush Index of Well-being, categorical scaling, standard gamble, and time tradeoff. The computer program improved the speed of collation of data for statistical analysis, provided a consistent interface among patients for utility assessments, and showed stable reporting of patient's well-being. These findings suggest that further development of computer-assisted assessments of patients' quality of life for clinical trials is warranted.

Clinical Trials as Topic↗
PubMed1995

IMPACT: an object-oriented graphical environment for construction of multimedia patient interviewing software.

This paper describes our software for rapid construction of multimedia computer interviews. The program, which we call IMPACT, was designed to measure preferences for health outcomes using the standard gamble and other decision analytic techniques. IMPACT is also a multimedia shell program that allows researchers to interactively construct patient interviewing instruments without programming or scripting. It supports the integration of text, graphics, synthesized speech, digital sound and QuickTime movies into interviewing instruments through a point-and-click interface. IMPACT also supports branching logic and randomizing the presentation order of materials within an instrument. This allows customization of the presentation based on patient responses and facilitates experimental designs. Validation studies show that preference assessments performed using IMPACT have high test-retest reliability (r = 0.83, n = 96). Post-test surveys (n = 52) show that most subjects understand valuation methods (86%) and believe that the explanations provided were clear (96%) and that methods were reasonable (80%). The majority of subjects thought the preference assessment methods were not difficult to use (53%) and would have been comfortable using such methods for medical decisions (53%).

Computer Graphics↗
PubMed1993

Monitoring free-text data using medical language processing.

In this paper, we describe a software system for automated monitoring of free-text data in a medical information system that we call RadTRAC (Radiology Text Report Analyzer and Classifier). RadTRAC uses a medical language processing tool and rules derived from statistical analysis of a database to process free-text chest X-ray (CXR) reports and identify reports that describe new or expanding neoplasms for the purpose of monitoring the follow-up of these patients. To evaluate the RadTRAC system, we examined a set of 470 consecutive radiology reports at the Veterans Administration Medical Center, Palo Alto, CA. We compared RadTRAC classification of CXR reports with retrospective expert classification of the reports and with clinical classification from CXR films as recorded in a logbook while the films were being read. The RadTRAC system had a sensitivity of 90% and a specificity of 82% using the logbook as the gold standard. This was similar to the performance of expert radiologists (sensitivity, 92%; specificity, 90%). We then reviewed the charts, appointment schedule, and subsequent X-ray reports of cases either in the logbook or that were identified by RadTRAC as needing follow-up. Two cases in the logbook could have potentially benefited from an automatic monitoring system to ensure follow-up. RadTRAC identified six confirmed new tumors or new metastatic lesions that were not in the logbook. Six other cases were identified by the RadTRAC system with suspicious X-ray findings that had either no follow-up or no further mention of the X-ray lesion in medical records. This suggests that a reminder system based on the RadTRAC technology would be potentially useful.

Abstracting and Indexing↗
PubMed1993

The side effects of antipsychotic drugs and patients' quality of life: patient education and preference assessment with computers and multimedia.

Determining the relative value of novel antipsychotics such as clozapine requires measures of the utility of their different side-effect profiles. Many of these side effects (SE) are complex and difficult to describe adequately. Schizophrenic patients are also difficult to interview reliably. Even in normal subjects, utility assessment can be tedious, inconsistent, and difficult for subjects to understand. We addressed these challenges by developing a multimedia patient education and utility assessment tool. SE were described using short video sequences accompanied by digitized voice descriptions. Patients' preferences were assessed using visual analog scales, pairwise comparisons, and standard gambles. These assessment techniques were carefully explained and logically integrated. Instructions were presented both by digitized voice and in print, and, if necessary, were clarified by a moderator. Animated displays were used to graphically display probability. Reminder pictures, comprehension tests and validation questions were used throughout the survey. Thirty-three patients from VA and public clinic inpatient and outpatient settings took the survey. Five psychiatrists were surveyed as a reference group. Patients understood the SE and the survey (92% mean comprehension) and their answers were internally valid and consistent (74% internal consistency). The standard gamble disutilities for the SE were substantial, ranging from 12-20% decrease in their quality of life. Computer-based, multimedia techniques are useful in conducting utility assessment and evaluating its validity. They allow effective patient education and elicitation of useful values, even in subjects with cognitive impairments.

Adult↗
PubMed1993

Automated linkage of free-text descriptions of patients with a practice guideline.

The process of applying a practice guideline to a patient requires a great deal of clinical data. AAPT (Appropriateness-Assessment Processing from Text) is an experimental computer program that can assess the appropriateness of coronary-artery bypass grafting surgery (CABG) in patients with coronary-artery disease (CAD) and chronic stable angina from the admission summaries of those patients. The AAPT architecture combines natural-language processing (NLP) and probabilistic inference. The NLP module identifies single clinical concepts of interest in the free-text document. The probabilistic inference module, a Bayesian belief network, estimates values for variables not specifically mentioned. AAPT produces a patient's summary of CAD that is similar to a manually generated clinical summary. Work is ongoing to improve AAPT and evaluate it as a tool to assist in the dissemination of guidelines and as a tool to encourage adherence to practice guidelines.

Angina Pectoris↗
PubMed1993

A multimedia preference-assessment tool for functional outcomes.

Functional outcomes of clinical trials are often reported as number of dependencies in activities of daily living (ADLs). Quality-weighting for the ADLs has not been reported. We designed and pilot-tested ADLIB (ADL Index Builder), a multimedia computer program, that presents ADL health states to subjects and elicits from subjects a rating for the quality of life of each health state. Subjects, who were patients over age 50 without previous computer experience, found the program easy to use. Health care professionals specializing in geriatrics confirmed that the ADL presentations used in the program are in accord with typical practice in scoring ADLs. We plan to use the program to obtain population-based preference ratings that can be used to assess efficacy of clinical trials and to provide quality-weights for cost-effectiveness analysis.

Activities of Daily Living↗
PubMed1992

Advanced computer programs for drug dosing that combine pharmacokinetic and symbolic modeling of patients.

In this paper, we describe our design for advanced drug dosing programs that "reason" using a combination of Bayesian pharmacokinetic modeling and symbolic modeling of patient status and drug response. Our design is similar to the design of the Digitalis Therapy Advisor program, but extends this previous work by incorporating a Bayesian pharmacokinetic model, performing a "meta-level" analysis of drug concentrations to identify sampling errors and changes in pharmacokinetics, and including the results of this analysis in reasoning for dosing and therapeutic monitoring recommendations. The design has been implemented in a program for aminoglycoside antibiotics called Aminoglycoside Therapy Manager. The program is user-friendly and runs on low-cost general-purpose hardware. The initial validation study showed that the program was as accurate in predicting future drug concentrations as an expert using commercial Bayesian forecasting software and that its dosing recommendations were similar to those of an expert.

Aminoglycosides↗
PubMed1992

Practical computer-assisted dosing for aminoglycoside antibiotics.

In principle, computer-assisted individualization of antibiotic dosing offers the prospect of better patient outcomes through improved dosing precision. In practice, however, the expertise in pharmacokinetics required to operate these programs has precluded their use by most physicians and pharmacists. We developed a computer program for individualization of dosing of aminoglycoside antibiotics under conditions in which access to experts in pharmacokinetics is impractical. The program is accurate, yet it requires less effort for data collection than previous drug dosing programs did. The program generates advice on a broad spectrum of topics, including dose adjustment, interpretation of measured drug concentrations in blood, and recommendations for monitoring drug concentrations. We tested its performance by prospectively comparing it with a clinical pharmacokinetic consultation service in a series of 78 consecutive patients. There were no differences in accuracy or bias in the prediction of drug concentrations. The rate of agreement between the program's dosing recommendations and those of the consultation service was 67 percent. This rate of agreement is typical of interexpert variation. In a stratified set of 24 of the 41 instances with significant disagreement regarding the recommended dose, experts ranked the program's recommendations as highly as those of the consultation service (95% confidence interval for difference in rank, -0.30 less than chi less than 0.47). The results suggest that expert systems can be coupled with pharmacokinetic dosing programs to deliver high-quality clinical recommendations for administration of antimicrobial agents.

Adult↗
PubMed1992

Anticoagulation therapy advisor: a decision-support system for heparin therapy during ECMO.

We present a case study describing our development of a mathematical model to control a clinical parameter in a patient--in this case, the degree of anticoagulation during extracorporeal membrane oxygenation (ECMO) support. During ECMO therapy, an anticoagulant agent (heparin) is administered to prevent thrombosis. Under- or over-coagulation can have grave consequences. To improve control of anticoagulation, we developed a pharmacokinetic-pharmacodynamic (PK-PD) model that predicts activated clotting times (ACT) using the NONMEM program. We then integrated this model into a decision-support system, and validated it with an independent data set. The population model had a mean absolute error of prediction for ACT values of 33.5 seconds, with a mean bias in estimation of -14.3 seconds. Individualization of model-parameter estimates using nonlinear regression improved the absolute error prediction to 25.5 seconds, and lowered the mean bias to -3.1 seconds. The PK-PD model is coupled with software for heuristic interpretation of model results to provide a complete environment for the management of anticoagulation.

Blood Coagulation Disorders↗
PubMed1991

The design of a user interface for a ventilator-management advisor.

The lack of user acceptance for many medical decision-support systems should force medical software developers to rethink strategies for user interaction with decision-support programs. Participatory design is an emerging method for the development for computer applications that emphasizes user involvement in both the design and implementation phases. We have applied participatory design to the development of a user interface for VentPlan, an application that assists physicians in the management of artificial respiration of critically ill patients. In this paper, we present a case history of the participatory design process and describe the resulting interface for the VentPlan program. As a result of applying participatory design ideas, we gained insight as to how to implement VentPlan more effectively.

Critical Care↗
PubMed1989

Continuous parenteral infusion of vitamin E pharmacokinetics and bilirubin production in premature neonates.

We conclude that 5 mg/kg of vitamin E, administered intra-arterially as an 8-hour continuous infusion, significantly and predictably raises serum vitamin E levels into the supraphysiologic range with no apparent side effects. In a group of premature infants whose initial serum vitamin E levels were generally greater than or equal to 0.5 mg/dL, no decrease in bilirubin production was observed. Thus, vitamin E deficiency probably does not play a prominent role in jaundice of prematurity.

Bilirubin↗
PubMedDate not supplied

Comparison of preferences for health outcomes in schizophrenia among stakeholder groups.

BACKGROUND: To determine the effectiveness of psychiatric interventions for use in cost-effectiveness analysis, we assessed the feasibility of using a multimedia computer survey to study preferences (utilities) for health outcomes among persons with schizophrenia, family members of persons with schizophrenia, health professionals, and the public. METHODS: We developed videos depicting two patterns of mental health impairment in schizophrenia, both with and without pseudo-parkinsonism side-effects. These descriptions were integrated into a computer program that measured preferences using two psychometric methods: (1) standard gamble and (2) a visual analog scale. This program was used to compare preferences among potential stakeholder groups. RESULTS: 20 persons with schizophrenia, 11 family members, 20 healthy volunteers and 14 health professionals participated in the computerized interview. All but one subject completed the survey. The correlation among ratings of various states was high (r=0.7-0.95) and ratings were internally consistent in 89% of participants. There were significant differences in values between groups for health states (p=0.024) and in values for the effects of pseudo-parkinsonism on quality of life (p<0.001). Persons with schizophrenia valued the disease states more highly and placed more significance than did other groups on the effects of pseudo-parkinsonism on quality of life. CONCLUSIONS: Computer-based multimedia techniques can offer a feasible and valid approach to measure preferences for outcomes in schizophrenia. The study found significant differences in preferences among stakeholder groups for schizophrenia outcomes. Further work is needed to clarify how these differences affect clinical decision-making and policies for health resource allocation.

Adult↗