Special review: game theory to analyse management options in gastro-oesophageal reflux disease

Cry wolf and inflate medical urgency to expedite consult resolution through gastrointestinal endoscopy

BACKGROUND AND AIMS

To expedite a consult resolution, referring physicians sometimes inflate the urgency and need for endoscopic workup. The aim of the present decision analysis was to study the impact of inflationary indication on the expected benefits to gastroenterologists and referring physicians.

METHODS

The study aims were pursued in terms of game theory and medical decision analysis using decision trees. Different outcomes associated with true versus false urgent indication in immediate versus delayed endoscopy were ranked according to different preference schemes of gastroenterologists versus referring physicians.

RESULTS

The decision analysis shows that inflating the urgency of indication for endoscopy reduces the benefit from the perspective of gastroenterologists and referring physicians alike. Raising the level of false urgent indications results in a lost opportunity for immediate endoscopy among patients with true urgent indications and, thus, diminishes the overall benefit of endoscopy. By comparison, all other influences play only a marginal role. For referring physicians, the small benefit of expediting nonurgent endoscopies by exaggerated claims does not compensate for the concomitant loss of truly needed endoscopy slots. For gastroenterologists, a small benefit derived from delaying endoscopies in patients with false urgent endoscopies rapidly wears off as inflationary indications become common practice.

CONCLUSION

An underlying communication problem between referring physicians and gastroenterologists needs to be resolved by educating referring physicians about the operative exigencies of endoscopy units and about the true appearance of alarm symptoms in common digestive diseases.

The relevance of Nash equilibrium to psychiatric disorders

In game theory, the word 'game' is used to describe any interdependence between interacting parties, and the Nash equilibrium is a prominent tool for analysing such interactions. I argue that the concept of the Nash equilibrium may also be used in non-gaming contexts. An individual is in a Nash equilibrium if his or her beliefs are consistent with his or her actions. Given that discordance between beliefs and behaviour is a typical cause of psychiatric disorders, individuals who are not in a Nash equilibrium are likely to be affected by such disorders. In this regard, the concept of the Nash equilibrium could aptly be introduced into the medical practitioner's vocabulary for describing a patient's mental health status.

Nonlinear least-squares data fitting in Excel spreadsheets

We describe an intuitive and rapid procedure for analyzing experimental data by nonlinear least-squares fitting (NLSF) in the most widely used spreadsheet program. Experimental data in x/y form and data calculated from a regression equation are inputted and plotted in a Microsoft Excel worksheet, and the sum of squared residuals is computed and minimized using the Solver add-in to obtain the set of parameter values that best describes the experimental data. The confidence of best-fit values is then visualized and assessed in a generally applicable and easily comprehensible way. Every user familiar with the most basic functions of Excel will be able to implement this protocol, without previous experience in data fitting or programming and without additional costs for specialist software. The application of this tool is exemplified using the well-known Michaelis-Menten equation characterizing simple enzyme kinetics. Only slight modifications are required to adapt the protocol to virtually any other kind of dataset or regression equation. The entire protocol takes approximately 1 h.

Understanding medication compliance and persistence from an economics perspective

OBJECTIVES

An increased understanding of the reasons for noncompliance and lack of persistence with prescribed medication is an important step to improve treatment effectiveness, and thus patient health. Explanations have been attempted from epidemiological, sociological, and psychological perspectives. Economic models (utility maximization, time preferences, health capital, bilateral bargaining, stated preference, and prospect theory) may contribute to the understanding of medication-taking behavior.

METHODS

Economic models are applied to medication noncompliance. Traditional consumer choice models under a budget constraint do apply to medication-taking behavior in that increased prices cause decreased utilization. Nevertheless, empiric evidence suggests that budget constraints are not the only factor affecting consumer choice around medicines. Examination of time preference models suggests that the intuitive association between time preference and medication compliance has not been investigated extensively, and has not been proven empirically. The health capital model has theoretical relevance, but has not been applied to compliance. Bilateral bargaining may present an alternative model to concordance of the patient-prescriber relationship, taking account of game-playing by either party. Nevertheless, there is limited empiric evidence to test its usefulness. Stated preference methods have been applied most extensively to medicines use.

RESULTS

Evidence suggests that patients' preferences are consistently affected by side effects, and that preferences change over time, with age and experience. Prospect theory attempts to explain how new information changes risk perceptions and associated behavior but has not been applied empirically to medication use.

CONCLUSIONS

Economic models of behavior may contribute to the understanding of medication use, but more empiric work is needed to assess their applicability.

Personal view: 'don't ask, don't tell'--the undesirable consequences of incidental test results in gastroenterology

A gastroenterologist is frequently approached to perform an endoscopic procedure after an incidental test has resulted in an unexpected positive finding. Should the incidental test result be ignored or automatically followed by an endoscopic procedure? The present analysis strives to characterize the common pattern of such scenarios and resolve their underlying dilemma. A model of game theory is used as a mathematical tool to develop general management strategies. Three clinical scenarios are used as examples to demonstrate this approach. The model is based on how doctors rank the various outcomes with which they are confronted by the incidental test results. The ranks of different outcomes are listed in a decision matrix that is converted into a two-by-two, non-zero, ordinal game. All scenarios of incidental test results emerge as a similar type of game that is best played by both parties adhering to the same set of strategies: 'Don't do the test' and 'don't respond to whatever test result it yields'. These two strategies lead to a Nash equilibrium for a non-zero game, where neither party can improve its payoff any further by choosing a different strategy. Although the equilibrium does not provide the individual players with their best possible payoff, it yields the best overall outcome available to both parties given the economic and medical constraints of the situation.

Decision analysis in clinical gastroenterology

OBJECTIVES

Although the tools of medical decision analysis have been mostly used to address complex issues of healthcare and management policies, an important role remains for decision analysis to play in solving mundane medical problems of daily practice. The present article aims to restate the origins of decision analysis and to demonstrate the utility of decision models in clinical gastroenterology.

METHODS

Three clinical scenarios are presented to illustrate the applicability of decision analysis in clinical gastroenterology. The examples are modeled as simple decision trees and phrased in terms of threshold analysis.

RESULTS

In spite of its striking simplicity, the framework of threshold analysis is able to capture a large variety of heterogeneous and often perplexing medical problems. Rather than calculate a cost-effectiveness or cost-benefit ratio, the result of the analysis is expressed as a probability value, which forms the threshold between the two choices against or in favor of a particular medical action. For most analyses little if any calculation is needed to solve the decision tree, and the final outcome of the analysis can be derived based on comparative estimates and considerations of magnitude only.

CONCLUSIONS

The study demonstrates that threshold analysis can serve as a simple and convenient instrument to solve a large variety of problems in clinical gastroenterology.