James P. Kahan

OncoSurge: A Strategy for Improving Resectability With Curative Intent in Metastatic Colorectal Cancer

PURPOSE Most patients with colorectal liver metastases present to general surgeons and oncologists without a specialist interest in their management. Since treatment strategy is frequently dependent on the response to earlier treatments, our aim was to create a therapeutic decision model identifying appropriate procedure sequences. METHODS We used the RAND Corporation/University of California, Los Angeles Appropriateness Method (RAM) assessing strategies of resection, local ablation and chemotherapy. After a comprehensive literature review, an expert panel rated appropriateness of each treatment option for a total of 1,872 ratings decisions in 252 cases. A decision model was constructed, consensus measured and results validated using 48 virtual cases, and 34 real cases with known outcomes. RESULTS Consensus was achieved with overall agreement rates of 93.4 to 99.1%. Absolute resection contraindications included unresectable extrahepatic disease, more than 70% liver involvement, liver failure, and being surgically unfit. Factors not influencing treatment strategy were age, primary tumor stage, timing of metastases detection, past blood transfusion, liver resection type, pre-resection carcinoembryonic antigen (CEA), and previous hepatectomy. Immediate resection was appropriate with adequate radiologically-defined resection margins and no portal adenopathy; other factors included presence of < or = 4 or > 4 metastases and unilobar or bilobar involvement. Resection was appropriate postchemotherapy, independent of tumor response in the case of < or = 4 metastases and unilobar liver involvement. Resection was appropriate only for > 4 metastases or bilobar liver involvement, after tumor shrinkage with chemotherapy. When possible, resection was preferred to local ablation. CONCLUSION The results were incorporated into a decision matrix, creating a computer program (OncoSurge). This model identifies individual patient resectability, recommending optimal treatment strategies. It may also be used for medical education.

Cooperation and Group Size in the N-Person Prisoners' Dilemma

This study explores the relationship between group size and member cooperation when individual and group interests conflict. Existing theories incorrectly imply that larger groups should experience more difficulty in providing “public goods” (goods whose benefits are not confined to the purchaser). A theoretically based typology that identifies nine systematic patterns associated with changes in group size and parameters of individual and group payoff structure is presented. The typology describes nine different ways in which group size can affect cooperation in the provision of public goods. In a computer-administered experiment using three of these nine types and group sizes of three, six, and nine, 90 college students were given sequences of opportunities to choose between “cooperation” (which benefited everyone) and “noncooperation” (which benefited the chooser but harmed everyone else). For one of these types, a counter-intuitive but theoretically predicted positive relationship between group size and cooperation was found. Two explanations for a theoretically unexpected negative relation between group size and cooperation in the other conditions are developed, one based on Steiners concept of a conjunctive task, the other based on the decreasing information value of responses in larger groups.

MEASURING THE NECESSITY OF MEDICAL PROCEDURES

This is a report on the extension of the concept of the appropriateness of a procedure to the necessity, or crucial importance, of that procedure. To state that a procedure is crucial means that withholding the procedure would be deleterious to the patients health. Appropriateness and necessity ratings for six procedures were obtained using a modified Delphi panel process developed in earlier work. Panels were composed of practicing clinicians who were recognized leaders in their fields. The panels included both performers and nonperformers of the procedure under discussion. For most procedures and panelists, necessity was related to appropriateness, but was distinct from it. The proportion of indications for which the procedure was crucial varied in clinically consistent ways both among and within procedures. However, panelists did not achieve a consensus on necessity. Further research is suggested to refine the method to promote consensus and to validate further the ratings of necessity. In conclusion, necessity ratings can be used together with appropriateness ratings to address not only the overuse of procedures, but also to indicate limited access to care through underuse of procedures.

When three is not always two against one: Coalitions in experimental three-person cooperative games

Abstract Four models of coalition formation are tested in a computer-controlled experiment in which three players negotiated to form coalitions in order to gain rewards for themselves. Formation of the grand coalition of all three players as well as any of the three possible 2-person coalitions is permitted. The results indicate that the grand coalition is the most likely to form, followed by the coalition between the two strongest players. The individually rational bargaining set model of coalition formation is supported over an egalitarian model, the Shapley value, and the coalitionally rational bargaining set model. Various measures of the progress of negotiations are introduced, examined, and discussed in an effort to provide an increased data base for the establishment of a behavioral theory of bargaining and coalition formation.

Is the involvement of opinion leaders in the implementation of research findings a feasible strategy

BackgroundThere is only limited empirical evidence about the effectiveness of opinion leaders as health care change agents.AimTo test the feasibility of identifying, and the characteristics of, opinion leaders using a sociometric instrument and a self-designating instrument in different professional groups within the UK National Health Service.DesignPostal questionnaire survey.Setting and participantsAll general practitioners, practice nurses and practice managers in two regions of Scotland. All physicians and surgeons (junior hospital doctors and consultants) and medical and surgical nursing staff in two district general hospitals and one teaching hospital in Scotland, as well as all Scottish obstetric and gynaecology, and oncology consultants.ResultsUsing the sociometric instrument, the extent of social networks and potential coverage of the study population in primary and secondary care was highly idiosyncratic. In contrast, relatively complex networks with good coverage rates were observed in both national specialty groups. Identified opinion leaders were more likely to have the expected characteristics of opinion leaders identified from diffusion and social influence theories. Moreover, opinion leaders appeared to be condition-specific. The self-designating instrument identified more opinion leaders, but it was not possible to estimate the extent and structure of social networks or likely coverage by opinion leaders. There was poor agreement in the responses to the sociometric and self-designating instruments.ConclusionThe feasibility of identifying opinion leaders using an off-the-shelf sociometric instrument is variable across different professional groups and settings within the NHS. Whilst it is possible to identify opinion leaders using a self-designating instrument, the effectiveness of such opinion leaders has not been rigorously tested in health care settings. Opinion leaders appear to be monomorphic (different leaders for different issues). Recruitment of opinion leaders is unlikely to be an effective general strategy across all settings and professional groups; the more specialised the group, the more opinion leaders may be a useful strategy.

Sensitivity and specificity of the RAND/UCLA Appropriateness Method to identify the overuse and underuse of coronary revascularization and hysterectomy

There is no empirical evidence on the sensitivity and specificity of methods to identify the possible overuse and underuse of medical procedures. To estimate the sensitivity and specificity of the RAND/UCLA Appropriateness Method. Parallel three-way replication of the RAND/UCLA Appropriateness Method for each of two procedures, coronary revascularization and hysterectomy. Maximum likelihood estimates of the sensitivity and specificity of the method for each procedure. These values were then used to re-calculate past estimates of overuse and underuse, correcting for the error rate in the appropriateness method. The sensitivity of detecting overuse of coronary revascularization was 68% (95% confidence interval 60-76%) and the specificity was 99% (98-100%). The corresponding values for hysterectomy were 89% (85-94%) and 86% (83-89%). The sensitivity and specificity of detecting the underuse of coronary revascularization were 94% (92-95%) and 97% (96-98%), respectively. Past applications of the appropriateness method have overestimated the prevalence of the overuse of hysterectomy, underestimated the prevalence of the overuse of the coronary revascularization, and provided true estimates of the underuse of revascularization. The sensitivity and specificity of the RAND/UCLA Appropriateness Method vary according to the procedure assessed and appear to estimate the underuse of procedures more accurately than their overuse.

Focus Groups as a Tool for Policy Analysis

Focus groups were formerly associated with market research but have recently gained some measure of social scientific respectability. In this article, I briefly recapitulate the history of focus groups and then examine their role in 4 (2 Dutch, 2 American) policy research projects. In each case, the focus groups provided an understanding of the interests and values of different stakeholder groups and per-mitted the analysts to predict the groups’ reactions to policy alternatives. This served to link the focus groups to the underlying policy problem, to set the policy issues in their appropriate context, to take due account of the technical complexities of the situation, and to orient toward integrating the results of the focus groups with the other tools used in the policy analysis. The four cases shared a “spiral” model approach to focus groups, in which the discussion moves from generic to specific toward the object of focus rather than tackling it directly. This permits both a breadth and depth of perspective and helps avoid posturing. I conclude that focus groups provide a value for policy analysis because they enable participant stakeholders to become part of the process, help uncover misunderstandings that conceal underlying agreements among stakeholders, and uncover potential problems of implementation.

Panellist consistency in the assessment of medical appropriateness

Where information about the appropriateness of a surgical procedure is lacking, expert panels have been used to establish guidelines for medical practitioners. Such a panel was convened to assess the appropriateness of percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery in the Netherlands. The panel, consisting of interventional cardiologists and cardiothoracic surgeons, used a modified Delphi process to rate 1126 clinical indications over two rounds. This article describes the degree of change in both agreement amongst members and in the appropriateness ratings over the two rounds, and examines the internal consistency of the ratings of individual panellists. Over the two rounds, agreement increased. Although most appropriateness ratings remained unchanged, there was significant movement from equivocal ratings to determinate ratings. While individual members showed some degree of inconsistency in their scoring, the panel as a whole scored very consistently. The observed changes in appropriateness were consistent with expectations, showing that the appropriateness method is used logically and consistently by panellists.

The Uniform N-Person Prisoner's Dilemma Game

The familiar two-person prisoners dilemma (PD) game can be considered a special case of a general family of games with more than two players. This family of games is of particular interest, having been suggested as a model for a variety of social conflict situations. A subset of this family of games, called the uniform PD, is defined, for which the members of the subset may be scaled along a dimension of competitiveness for any given number of players. An index of competitiveness was derived and tested for the three-person case. Sixty volunteer subjects played one of five three-person uniform PD games, chosen to vary across the range of values of the index. Each triad played 150 trials of the same game for points which were converted to cash at the end of the experiment. Subjects were run in triads homogeneous with respect to sex; effects due to that variable were absent. The obtained proportions of cooperative response were found to be strongly related to the value of the index. The approach offers a theoretical basis for assessment of behavior in multiperson conflict situations of the PD variety.

Decision making in a sequential search task

Ss were instructed to find the largest of a set of 200 different numbers, observed one at a time (when only the number currently observed could be declared the largest). Numbers sampled from one of three distributions, one with positive skew, one with negative skew, and one rectangular, were presented to three samples of 22 Ss, tested in small groups. The rectangular-distribution condition also was administered individually to a fourth sample of 22 Ss. Results failed to show effects of the distribution of numbers upon S’s performance. However, as predicted, Ss tested in groups tended to observe more cards before stopping than those tested individually. Data are analyzed in an effort to evaluate the adequacy of alternative “stopping rules” as strategies descriptive of Ss performance.