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Biomedical subjects

D G Fryback

Publications and source records attributed to D G Fryback.

At least 19 recordsLinked to original sources
PubMed1991

Cost-effectiveness of strategies for detecting diabetic retinopathy.

A computer model has been developed to determine cost-effectiveness of screening and treatment for diabetic retinopathy from a societal viewpoint. This model was used to evaluate biannual and annual screening programs using ophthalmoscopy, fundus photography with a "nonmydriatic camera," and photography with a "mydriatic camera." Computations were performed for three subpopulations formed by patients with younger onset diabetes (age at diagnosis less than 30 years) of 5 years or more duration, with older onset diabetes (age at diagnosis greater than or equal to 30 years) who are taking insulin, and with older onset diabetes not taking insulin. Population characteristics are from a well-described southern Wisconsin population where data are available, but the computer model may be specialized to other population. Generally costs of screening programs appear to be recovered by avoided costs of blindness in the population subgroups taking insulin; however, the cost of screening programs generally are not recovered by avoiding costs of blindness in the older onset population subgroup not taking insulin. It was estimated that supplying annual examination with mydriatic fundus photography as a screening program to a cohort of 1,000 diabetics from the younger onset population who have been diagnosed at least 5 years and who are currently not receiving care might save 319 sight years over the lifetime of the cohort. This program will save 62 sight years in an older onset cohort who are taking insulin, and 21 sight years in the older onset population not taking insulin (all benefits are presented as present values computed with an annual discount rate of 5%). Other programs achieve slightly lower savings in each subpopulation.

Adult↗
PubMed1988

The art of medicine: subjective measures as predictors of outcome in stroke and traumatic brain injury.

This study was designed to explore new ways of predicting the functional outcomes of stroke and brain injury patients. Upon admission and initial assessment of functional performance, we used an on-line computer program to indicate the most important and subjective judgment items to set rehabilitation goals for patients. The functional performance and discharge outcomes of patients from an inpatient program were measured by using five nonmedical functional items from the patient evaluation conference system (PECS). For stroke patients we most frequently selected motor loss, perceptual/cognitive deficit, spasticity, sensory deficit (PECS medical items), and comprehension (subjective cue). For traumatic brain injury patients, however, we selected motor loss, perceptual/cognitive deficit, spasticity (PECS medical items), communication, and comprehension (subjective cues). Data were statistically analyzed using the Fisher Exact Test. Of the medical function items, a level of independence in the sensory deficit function in stroke patients at admission was associated with a patient achieving independence in ambulation at discharge. Demonstrating a moderate or maximum level of attention, concentration, and realism was positively related to a patient achieving a level of independence in ambulation at discharge. Independence in the function items of behavior and interaction was associated with moderate or maximum levels of comprehension at admission. In traumatic brain injury patients, none of the subjective cues were associated with achieving independence at discharge in any of the functional levels. This paper demonstrates the value of developing a way to assess subjective measures that are based on their ability to predict outcomes. Using such a method, new predictive measures can be developed.

Adolescent↗
PubMed1986

A program for training and feedback about probability estimation for physicians.

Medical decisions are rarely made under conditions of complete certainty. In the past decade there has been a rapid growth of interest in formal methods for optimizing medical decisions under uncertainty. Application of decision-analytic methods requires physicians to make probability estimates about clinical events for which extensive data are not available. This paper describes a computer program to train physicians to be better probability estimators: to make probability estimates that are numerically meaningful for use in formal decision analyses. It is designed to be a stand-alone application requiring about 2 hours of physician time. Use requires an IBM-PC or compatible microcomputer with graphics adaptor and monitor, and 8087 coprocessor.

Computer-Assisted Instruction↗
PubMed1985

A cost-effectiveness analysis of screening for carcinoma of the prostate by digital examination.

While screening for carcinoma of the prostate by digital examination has been promoted as low in cost, safe, and effective, recent reviews have questioned its cost-effectiveness. Critical analysis has been lacking because of limited understanding of the preclinical phase of the disease and because of the absence of pertinent large-cohort data. We conducted a cost-effectiveness analysis of digital examination for prostate cancer using computer simulation of a large-cohort study. The simulation allowed for study of variations in critical assumptions about the disease and the screening procedure and keeps track of outcome descriptors such as total cost of the screening program and total years of life saved over the life of the cohort. Under assumptions favoring demonstrations of benefit from screening, modest increases in life expectancy were found in direct proportion to frequency and increasing costs of screening.

Aged↗
PubMed1979

A second look at the utility of radiographic skull examination for trauma.

A prospective study tested the hypothesis of Bell and Loop (1971) that 21 high yield findings are significantly associated with the presence of a skull fracture and can be used to decide which patients need skull radiography. In our study, 17 fractures were detected in 594 patients who had skull radiography because of trauma to the head. Six of these fractures occurred in children who had none of the 21 Bell and Loop high yield findings. These six patients were asymptomatic except for superficial injury at the site of trauma. Had the Bell and Loop criteria been used to decide which patients had skull radiography, 35% (all in children) of the fractures would have gone undetected. Thus, in our study population, the Bell and Loop high yield findings were not satisfactory criteria for the decision about obtaining skull films in children.

Adolescent↗
PubMed1979

Application of case series review results to the evaluation of individual cases in diagnostic radiology.

Probability theory provides a simple method for physicians to use their "intellectual linkages" to their past clinical experience in making current diagnoses. Only a pencil and paper are required for making a few likelihood calculations. To illustrate this method, evaluation was done of a new diagnostic sign (presence of knee ossification centers) for differentiating rubella from cytomegalovirus infection in young infants. Two practical questions can be answered by use of this method for calculating probabilities: (1) How certain can one be about either diagnosis when centers are present or absent? (2) How can other radiologists apply these results to their individual cases?

Cytomegalovirus Infections↗
PubMed1978

Informal use of decision theory to improve radiological patient management.

Six radiologists reviewed 50 urograms to determine whether arteriography or needle aspiration should be recommended for evaluation of a space-occupying renal lesion. In addition to their usual decision methods, they were encouraged to think about the problem from a decision theory viewpoint. No computations were required. It was found that even informal, non-numerical application of decision theory resulted in improved outcomes; further improvement was noted with explicit use of numerical methods.

Angiography↗
PubMed1978

Effect of screen/film combinations on diagnostic certainty: Hi-Plus/RPL versus Lanex/Ortho G in excretory urography.

A method using radiologists' subjective judgments was developed to compare the quality of the diagnostic image information from two different screen/film combinations (Hi Plus/RPL versus Lanex/Ortho G). A sample of 148 comparison film pairs was obtained in the course of performing 74 urograms using the two film/screen combinations. Each film pair was evaluated by three radiologists, using a blind film-reading format, in regard to:(1) anatomic diagnostic criteria visualization; (2) radiologic diagnostic certainty; (3) presence or absence of quantum mottle; and (4) prediction of which film of a pair was the rare earth screen/film combination. There was a significant difference favoring Hi Plus/RPL in perceived quality of visualization of anatomic criteria. However, the difference was more of statistical rather than practical importance. Diagnostic certainty differed only marginally and slightly favored the Hi Plus/RPL combination. No signficant differences in perception of quantum mottle were attributable to either screen/film combination. Radiologists were able to correctly identify the screen/film combination a significant proportion of the time. Radiation exposure with the Lanex/Ortho G combination was about half that with the Hi Plus/RPL combination. In this study, this would seem to constitute the major factor in film/screen selection.

Adult↗
PubMed1976

Use of excretory urogram information in the solution of the renal cyst/tumor/cortical nodule problem.

A decision analysis was made of the choice of angiography or needle aspiration to solve the cyst/tumor/cortical nodule diagnostic problem. With a test panel of 43 proved cases, the urogram diagnoses and decisions made at the time of actual patient management were compared with those made by a radiologist viewing the test panel as unknowns. The test panel radiologist based his recommendations on his subjective probability estimates of the three diagnoses in each case. Results indicate that the use of subjective probabilities increases the frequency of specific diagnoses and decreases inappropriate choice of angiography or aspiration.

Decision Making↗
PubMed1975

Likelihood ratios as a measure of the diagnostic usefulness of excretory urogram information.

The log likelihood ratio (LLR) method of assessing physicians' diagnostic judgments can be used to measure the diagnostic usefulness of radiologic information (urography in this study). The method requires collection of referring pbysicians' diagnosis prior to and after urography and their certainty in relation to receipt of the radiologic information. Physicians in daily practice are able to provide diagnoses and assign a percentage number to their certainty. The LLR method permits measurement of the diagnostic usefulness of both normal and abnormal urogram results. Retrospective chart review does not provide the same LLR results as those obtained from the prospective study.

Adult↗
PubMedDate not supplied

Technology assessment--an American view.

Technology assessment of an imaging method such as magnetic resonance (MR) is a complicated concept that includes aspects of epidemiology, biostatistics, clinical efficacy determination, outcomes assessment, and knowledge of the technical and medical bases of the imaging method under study. To enhance understanding of the interrelations of the different aspects of technology assessment, a hierarchical model is proposed. This extends from the basic imaging physics domain through clinical applications in diagnosis and treatment decisions to patient outcomes and ultimately societal considerations. This overview paper presents the conceptual continuum of the hierarchical model, and then describes the interrelationships among efficacy, cost effectiveness, and outcomes research as components embedded within the context of technology assessment. It also points out how scientific quality of research in MR imaging assessment can be enhanced through improved research design that takes into account basic concepts of the model.

Humans↗
PubMedDate not supplied

Evaluation of a computerized Bayesian model for diagnosis of renal cyst vs. tumor vs. normal variant from urogram information.

The diagnostic problem of cyst/tumor/normal variant raised on an excretory urogram leads to a decision to do needle aspiration or renal arteriography. This decision depends critically upon the probability distribution for the three diagnoses. A computerized Bayesian model of a uroradiologist's diagnostic process in solving the problem was developed. The model was based on subjective probabilities supplied by an experienced uroradiologist. The model was evaluated in terms of its ability to decrease the cost of further diagnosis regarding aspiration versus arteriography. The model's output was compared with decisions made by unaided radiologists viewing the same panel of 50 urogram test cases. Results indicate that the model does not improve upon the decisions made by a radiologist highly experienced with this diagnostic problem. However, the decisions made by unaided, less experienced radiologists result in greater cost than those of the model.

Angiography↗