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Evaluating medical expert systems: what to test and how?

Many believe that medical expert systems have great potential to improve health care, but few of these systems have been rigorously evaluated, and even fewer are in routine use. We propose the evaluation of medical expert systems in two stages: laboratory and field testing. In the former, the perspectives of both prospective users and experts responsible for implementation are valuable. In the latter, the study must be designed to test, in an unbiased manner, whether the system is used in clinical practice, and if it is used, how it affects the structure, process and outcome of health care encounters. We conclude with proposals for encouraging the objective evaluation of these systems.

Diagnosis, Computer-Assisted↗

Expert systems in medicine: a biomedical engineering perspective.

Knowledge-based expert systems for medical applications have received considerable attention in recent years. In this review, fundamental terms and notions of artificial intelligence techniques as applied to expert systems are introduced. The most well-known and influential medical expert systems are discussed in detail, and newer efforts are surveyed. A critical comparison of strengths and weaknesses of the systems is made, discussing depth and complexity of knowledge, acquisition of knowledge, user interaction and explanations, knowledge engineering tools, system evaluations, and user resistance. Long- and short-term trends are appraised.

Cholestasis↗

Development of an expert system for pediatric auditory brainstem response interpretation.

Expert systems are computer programs which incorporate artificial intelligence technology and are created to emulate the decision-making abilities of human experts. The advantage of such systems lies in their ability to capture and model expert problem solving knowledge in a domain and make it available to an unlimited number of consumers in an economic and efficient way. The purpose of this project was to develop an expert system to interpret infant auditory brainstem response data as entered by the user. The resulting system provides diagnostic conclusions regarding hearing status, type of hearing loss, and brainstem function at an accuracy level equal to that of a human expert.

Artificial Intelligence↗

[Medical expert systems. What are they and how should we organize our efforts?].

Medical expert systems have been developed for more than 20 years, in particular in the United States. Most existing systems are prototypes, and only a few commercial systems are available. The prototypes are generally limited in scope or functions (and have not been transferred to other users). However, in the near future we can expect useful applications to appear in special areas of medicine. In Norway we probably do not have the resources required to develop large commercial medical expert systems. If we want to develop medical expert systems, we should concentrate on limited areas. We must prepare the ground for future use of such systems in Norway. An important first step is to give health personnel basic education in the use of computers.

Expert Systems↗

Interpretation of surface EMGs in children with cerebral palsy: An initial study using a fuzzy expert system.

Surface EMG detected simultaneously at different muscles has become an important tool for analysing the gait of children with cerebral palsy (CP), as it offers essential information about muscular coordination. However, the interpretation of surface EMG is a difficult task that assumes extensive knowledge and experience. As such, this noninvasive procedure is not frequently used in the general clinical routine. An Artificial Intelligence (AI) system for interpreting surface EMG signals and the resulting muscular coordination patterns could overcome these limitations. To support such interpretation, an expert system based on fuzzy inference methodology was developed. The knowledge-base of the system implemented 15 rules, from which the fuzzy inference methodology performs a prediction of the effectiveness of the muscular coordination during gait. Our aim was to assess the feasibility and value of such an expert system in clinical applications. Surface EMG signals were recorded from the tibialis anterior, soleus muscle, and gastrocnemius muscles of children with CP to assess muscular coordination patterns of ankle movement during gait. Nineteen children underwent 114 surface EMG measurements. Simultaneously, the gait cycles of each patient were determined using foot switches and videotapes. From the EMG signals, the effectiveness of the ankle movement was predicted by the expert system, and predictions were classified using a three-point ordinal scale. In 91 cases (80%), the clinical findings matched the predictions of the expert system. In 23 cases (20%) the predictions of the expert system differed from the clinical findings with 12 cases revealing worse and 11 cases revealing better results in comparison to the clinical findings. As this study is a first attempt to verify the feasibility and correctness of this expert system, the results are promising. Further study is required to assess the correlation with the kinematic data and to include the whole leg.

Cerebral Palsy↗

An indicator of pesticide environmental impact based on a fuzzy expert system.

Pesticide use options available to farmers differ strongly with respect to the risks they pose to the environment. This paper proposes a fuzzy expert system to calculate an indicator "Ipest" which reflects an expert perception of the potential environmental impact of the application of a pesticide in a field crop. We defined four modules, one reflecting the presence (rate of application) of the pesticide, the other three reflecting the risk for three major environmental compartments (groundwater, surface water, air). The input variables for these modules are pesticide properties, site-specific conditions and characteristics of the pesticide application. For each input variable two functions describing membership to the fuzzy subsets Favourable (F) and Unfavourable (U) have been defined. These functions are based on criteria drawn from the literature or on the authors' expert judgment. The expert system calculates the value of modules according to the degree of membership of the input variables to the fuzzy subsets F and U and according to sets of decision rules. The four modules can be considered individually or can be aggregated (again according to membership to fuzzy subsets F and U and a set of decision rules) into the indicator Ipest. The system is flexible and can be turned to expert perception, it can be used as a decision aid tool to rank or choose between alternative pesticide application options with respect to their potential environmental impact. Results of a sensitivity analysis and module and Ipest scores for some pesticide application cases are presented. An agro-ecological indicator IPEST, based on the expert system, is proposed as a tool to assess the environmental impact of all pesticide applications related to a crop within a year. The practical implementation of the expert system and its validation are discussed.

Biodegradation, Environmental↗

Entering data into expert system for lower urinary tract pressure-flow studies.

This paper describes methods of entering data into an expert system used to study lower urinary tract pressure and flow. Data is usually entered into an expert system directly from the keyboard or on an online basis. We have developed a new method of offline data entry using a photoscanner. For this method, we developed versatile software to convert the graphic data read by a photoscanner to online data format. This software allows us to handle graphic data printed on paper in the same way as online data. The software is also designed to solve the problems caused by blurred lines or ink spots on printed charts. In other words, the software compensates for data reading errors caused by blurred or stained lines on printed charts. Because data can be entered through the photoscanner, the enormous volume of data already recorded in graphic forms can be used by the expert system. As a result, the diagnostic capability of the expert system is significantly improved.

Diagnosis, Computer-Assisted↗

The representation of uncertainty in medical expert systems.

The development of the rule-based expert system has provided important new techniques for the representation of knowledge. However, continued use of this representational scheme has highlighted some of its deficiencies. In particular, many within scientific and non-scientific fields attempting to use the rule-base design to describe natural phenomena often find it difficult to represent the complexities of the world as 'absolute' rules. For this reason, many investigators acknowledge the need to add an uncertainty mechanism to the rule-base construct. Such a facility would allow the quantification of accuracy or strength of association within individual rules Although agreement exists on the need for an uncertainty representation facility, the debate concerning the most appropriate methodology is far from resolved. The purpose of this paper is to provide a review and commentary on the current state of debate over the five most popular candidate uncertainty models: symbolic representation, MYCIN certainty factors, Bayesian, Dempster-Shafer and fuzzy set logic. The advantages and disadvantages of each uncertainty calculi will be presented and assessed with respect to their applicability to the medical expert systems domain.

Bayes Theorem↗

Evaluation of atopy through an expert system: description of the database.

BACKGROUND: In order to understand the medical decisions taken during the initial visit of a new asthmatic patient, a group of experts designed an expert system which provides conclusions about severity, precipitating factors and treatment. Rules for atopy and the assessment of allergic factors have been discussed and implemented in the expert system. Conclusions about severity have been yet validated using an appropriate methodology. OBJECTIVE: The aim of this study was to investigate a sample of 471 patients according to conclusions regarding atopy. METHODS: A total of 471 cases report forms (CRF) was filled in for adult asthmatic outpatients, seen for the first time in our clinic without emergency situations. Data of each CRF were used by the expert system to draw conclusions. The expert system discerns three patterns for atopy, yes, possible or no. The variables known to reflect different features according to the classification of asthma as atopic or not have been studied. The variables used in the rules for atopy, obviously linked to the conclusion, were not compared. For many medical problems no unique objective solution exists and this is why a group of patients with possible atopy was introduced. RESULTS: Patients with atopy had less severe asthma (P = 0.01), a better FEV1 value (P = 0.0007) and showed their first symptoms of asthma earlier (P = 0.00001) than patients without atopy. CONCLUSIONS: The characteristics of the group studied here are consistent with the literature. This could be considered as an indirect validation of the expert system. Moreover, patients with possible atopy show intermediate findings for these variables and it is possible to suggest a 'dose-effect' relationship.

Adolescent↗

[What to expect from expert systems for the diagnosis of functional bowel disorders].

The goal of this study was to evaluate the computer-aided diagnosis systems used for functional intestinal disorders published between 1970 and 1989. The methodology of all prospective studies published was evaluated using a score system of 12 items, filled in by two independent observers. A total of 10 studies were identified. None of the systems studied could truly be considered as an expert system. Most systems were not methodologically sound and the median score was 11 of a possible total of 24. The two principal characteristics of functional intestinal disorders are their high prevalence and the absence of objective diagnostic criteria. Taking these two facts into consideration when elaborating a diagnostic method, expert systems should be useful for teaching purposes and for conducting prospective epidemiologic or therapeutic studies. It seems too early, however, to consider the use of veritable expert systems as an aid to the practitioner in daily practice.

Algorithms↗

Expert systems in histopathology. IV. The management of uncertainty.

Expert systems deal with data that are categorical and conceptual, that represent elements of fuzzy sets and that often, by themselves, do not allow an unequivocal decision. The management of uncertainty in expert systems thus becomes a crucial issue. It involves defining measures of uncertainty and procedures for combining accumulating evidence in a manner that properly considers the dependence structure of diagnostic clues. Probability theory offers valuable procedures for uncertainty assessment; however, their practical application in the domain of quantitative histopathology and histopathologic diagnosis can be problematic.

Diagnosis, Computer-Assisted↗

Effects of a medical expert system on differential diagnosis of renal masses: a prospective study.

A medical expert system, RMDS, was used to prospectively evaluate patients undergoing nephrectomy for suspected renal masses. The effects of a medical expert system on differential diagnosis of renal masses were investigated. After RMDS consultation, three chief residents and one junior attending physician changed their preoperative diagnosis and significantly increased their diagnostic accuracy. The results indicate that the medical expert system may have an useful role in preoperative diagnosis of renal masses.

Bayes Theorem↗

Determinants of physician use of an ambulatory prescription expert system.

PURPOSE: To determine whether physician experience with and attitude towards computers is associated with adoption of a voluntary ambulatory prescription writing expert system. METHODS: A prescription expert system was implemented in an academic internal medicine residency training clinic and physician utilization was tracked electronically. A physician attitude and behavior survey (response rate=89%) was conducted six months after implementation. RESULTS: There was wide variability in system adoption and degree of usage, though 72% of physicians reported predominant usage (> or =50% of prescriptions) of the expert system six months after implementation. Self-reported and measured technology usage were strongly correlated (r=0.70, p<0.0001). Variation in use was strongly associated with physician attitude toward issues of system efficiency and effect on quality, but not with prior computer experience, level of training, or satisfaction with their primary care practice. Non-adopters felt that electronic prescribing was more time consuming and also more likely to believe that their patients preferred hand-written prescriptions. CONCLUSION: A voluntary electronic prescription system was readily adopted by a majority of physicians who believed it would have a positive impact on the quality and efficiency of care. However, dissatisfaction with system capabilities among both adopters and non-adopters suggests the importance of user education and expectation management following system selection.

Ambulatory Care Information Systems↗

XNEOr: development and evaluation of an expert system to improve the quality and cost of decision-making in neuro-oncology.

The treatment of brain tumors requires a large team of medical experts. However, the process of medical decision-making for these patients is hampered by the frequent inaccessibility of the experts because of conflicting scheduling, inconsistencies in the management of different patients, and the fact that multiple experts often yield multiple opinions. The goals of this work were (1) to develop and validate an expert system to assist the medical team deliver efficient, quality care to children with recurrent medulloblastoma, a common type of pediatric brain tumor, and (2) to determine if the expert system can be used as an educational tool. The results of our study indicate that residents enjoy learning by using XNEOr, the brain tumor expert system. XNEOr enabled residents to order appropriate ancillary tests for patients and to make fewer incorrect treatment decisions. The potential net effect of residents using XNEOr may be increased patient and family satisfaction and decreased probability of medical liability. At a time of important changes in our health care system, novel expert systems hold promise as tools to reduce medical costs, improve the quality of multi-expert medical care, and advance health care education.

Brain Neoplasms↗

The use of an enteral expert system in the prescription of enteral formulas in a university hospital.

A personal computer-based expert system has been developed for the prescription of enteral formulas based on patient-need characteristics. Two hundred twelve inpatients in a university hospital setting were prospectively evaluated to compare the identity and cost of the enteral formula prescribed by the expert system with the identity and cost of the enteral formula prescribed by the ward team. Two hundred seven patients had complete data to allow analysis. There was a mean cost savings (+/-SD) of $1.18 +/- 7.69/d for each patient using the expert system compared with the MD-prescribed formula (P = 0.023). We project that the use of this program would save $27,564/y in our hospital (an average of 23,360 patient/days of enteral feeding per year). We conclude that the use of an expert system can be cost-effective in the prescription of enteral formulas for hospitalized patients.

Adult↗

Expert systems in treating substance abuse.

Computer programs can assist humans in solving complex problems that cannot be solved by traditional computational techniques using mathematic formulas. These programs, or "expert systems," are commonly used in finance, engineering, and computer design. Although not routinely used in medicine at present, medical expert systems have been developed to assist physicians in solving many kinds of medical problems that traditionally require consultation from a physician specialist. No expert systems are available specifically for drug abuse treatment, but at least one is under development. Where access to a physician specialist in substance abuse is not available for consultation, this expert system will extend specialized substance abuse treatment expertise to nonspecialists. Medical expert systems are a developing technologic tool that can assist physicians in practicing better medicine.

Decision Support Techniques↗

Validating a model: the expert systems research approach.

The nursing profession is invariably resorting to the use of models to depict the key facets and relationships that are being uncovered through research. The expert systems approach to model validation incorporates into research methods a process authenticated by the disciplines of engineering and information systems. The seven-step process developed for a computer expert systems approach has been transformed into a Nine-Stage Schematic of the Process for Validating System Models. This article proposes the expert systems research approach to model validation as a means of clarifying and defining models within the discipline of nursing. This process was used to validate Boswell's Model of the Structure of Knowledge for Nursing, and the process conducted for this model will be discussed as a case study of the use of the expert systems approach for model validation.

Expert Systems↗

Design and development of an expert system for student use in a school of nursing.

Use of the expert system as a tool for clinical decision support for students and practitioners of nursing is a subject of much discussion and developmental activity. A prototype of a nursing expert system was designed for use in a simulated laboratory environment to provide nursing students with decision support in identifying and managing common postoperative complications. Formative evaluation of the system with associate and baccalaureate nursing students elicited positive response and formed the basis for ongoing program refinement. The practicing nurse of the future must understand expert system use in order to consider the implications and potential of such a clinical tool in nursing practice.

Computer-Assisted Instruction↗