Stephen D. Roberts

Cost-Effective Care of End-Stage Renal Disease: A Billion Dollar Question

We examined the survival time and costs of therapy for patients with end-stage renal disease. A computer simulation model of the current system was constructed to estimate the cost-effectiveness of home and center hemodialysis and live related as well as cadaver donor renal transplantation. Analysis of the simulation showed that live related donor transplantation was the least costly and had the greatest survival time, while center hemodialysis had the poorest cost-effectiveness. By simulating changes to the present system of care, we found that shifts from center dialysis to either home dialysis or cadaver donor transplantation would save

Input modeling with the Johnson system of distributions

7000 to

Modeling Input Processes With Johnson Distributions

8000 per life year, or

Quantifying uncertainty in medical decisions

284 million per year for the existing end-stage renal disease population. However, if legislative changes fail to produce real shifts from center hemodialysis, costs will increase. We conclude that the substantial costs for end-stage renal disease can be contained by shifting from the widespread use of center hemodialysis.

Cost-Effective Oxygen Therapy

This paper provides an introduction to the Johnson translation system of probability distributions, and it describes methods for using the Johnson system to model input processes in simulation experiments. The fitting methods based on available data are incorporated into the public-domain software package FITTR1. To handle situations in which little or no data is available, we present a visual interactive method for subjective distribution fitting that has been implemented in the public-domain software package VISIFIT. We present several examples illustrating the use of FITTRI and VISIFIT for simulation input modeling.

Health care costs of medical patients at an urban care center.

This paper provides an introduction to the Johnson translation system of probability distributions, and it describes methods for using the Johnson system to model input processes in simulation experiments. For situations in which little or no sample information is available, we have developed a visual interactive method to estimate bounded Johnson distributions subjectively; and we have implemented this technique in VESIFIT, a public-domain software package. For fitting all types of Johnson distributions based on sample data, we have implemented several new statistical-estimation methods as well as some standard techniques in FITTR1, another public-domain software package. We present several examples illustrating the use of VISIFIT and FITTR1 for simulation input modeling.

Unexpected Hospital Admissions Among Patients With Diabetes Mellitus

Effective handling of uncertainty is one of the central problems in medical decision making. The sources and effects of uncertainty in medical decision making are examined and some new quantitative approaches for solving the associated problems are outlined. To handle uncertainty in the branching probabilities and node utilities for probability trees representing alternative treatment strategies, a public domain software package that can be used for the construction, analysis and comparison of probability trees with random parameters was developed. To facilitate specification of the random variables that arise in medical decision making problems, public domain software packages for both data-driven and subjective estimation of probability densities from the Johnson translation system of distributions have also been developed. For the analysis of complex problems that cannot be adequately represented by probability trees or by simple stochastic processes such as Markov chains, network simulation approaches that are oriented toward the sequence of activities seen by individual patients in the course of treatment are described.

Teaching simulation to undergraduates

Excerpt When the outcome of a clinical trial shows that one treatment increases survival over alternative therapies, the result may be expected to establish a new standard of medical practice, part...

Are Home Hemodialysis Aides Cost-effective?: Cost of Home Hemodialysis Aides

Many cost containment strategies advocate that physicians should use fewer or less costly resources. In order to place these strategies in perspective, components of charges (costs) for medical patients at an urban center were examined to ascertain their contribution to the total health care bill. Contributions to total costs by location of service were: inpatient, 77.9%; outpatient, 17.1%; emergency room, 5.0%. Contributions by cost category were: facility charge, 52.8%; tests, 25.6%; pharmaceuticals, 11.0%. A goal to reduce total costs by 5% would require reducing pharmaceuticals by 45.4% or tests by 19.5%. In contrast, the same goal could be accomplished by reducing hospitalization by only 6.4%. If a strategy increased ambulatory costs by 5%, but resulted in a 7.5% decrease in hospitalization, the total health care costs would still decrease by 5%. Thus, rather than using fewer and less costly resources, physicians are encouraged to use more resources in ambulatory care to prevent morbidity requiring hospitalization.