Ron Koymans

Specifying real-time properties with metric temporal logic

This paper is motivated by the need for a formal specification method for real-time systems. In these systemsquantitative temporal properties play a dominant role. We first characterize real-time systems by giving a classification of such quantitative temporal properties. Next, we extend the usual models for temporal logic by including a distance function to measure time and analyze what restrictions should be imposed on such a function. Then we introduce appropriate temporal operators to reason about such models by turning qualitative temporal operators into (quantitative) metric temporal operators and show how the usual quantitative temporal properties of real-time systems can be expressed in this metric temporal logic. After we illustrate the application of metric temporal logic to real-time systems by several examples, we end this paper with some conclusions.

(Real) Time: A Philosophical Perspective

We present a perspective on the relationship between time and realtime. This perspective originates from a philosophical viewpoint concerning models of time that does not consider quantitative timing issues such as those relevant for real-time computing. This starting point is then adapted to incorporate real-time features. In doing so we try to combine the views on time and real-time forwarded by mathematical logic and by computer science. To illustrate these issues we use temporal logic, but many of the results presented are independent from a particular language and are also relevant for other (real) time formalisms.

Care coordination in a business-to-business and a business-to-consumer model for telemonitoring patients with chronic diseases

Introduction For telemonitoring to support care coordination, a sound business model is conditional. The aim of this study is to explore the systemic and economic differences in care coordination via business-to-business and business-to-consumer models for telemonitoring patients with chronic diseases. Methods We performed a literature search in order to design the business-to-business and business-to-consumer telemonitoring models, and to assess the design elements and themes by applying the activity system theory, and describe the transaction costs in each model. The design elements are content, structure, and governance, while the design themes are novelty, lock-in, complementarities, and efficiency. In the transaction cost analysis, we looked into all the elements of a transaction in both models. Results Care coordination in the business-to-business model is designed to be organized between the places of activity, rather than the participants in the activity. The design of the business-to-business model creates a firm lock-in but for a limited time. In the business-to-consumer model, the interdependencies are to be found between the persons in the care process and not between the places of care. The differences between the models were found in both the design elements and the design themes. Discussion Care coordination in the business-to-business and business-to-consumer models for telemonitoring chronic diseases differs in principle in terms of design elements and design themes. Based on the theoretical models, the transaction costs could potentially be lower in the business-to-consumer model than in the business-to-business, which could be a promoting economic principle for the implementation of telemonitoring.

Assessment of a Business-to-Consumer (B2C) model for Telemonitoring patients with Chronic Heart Failure (CHF)

BackgroundThe purpose of this study is to assess the Business-to-Consumer (B2C) model for telemonitoring patients with Chronic Heart Failure (CHF) by analysing the value it creates, both for organizations or ventures that provide telemonitoring services based on it, and for society.MethodsThe business model assessment was based on the following categories: caveats, venture type, six-factor alignment, strategic market assessment, financial viability, valuation analysis, sustainability, societal impact, and technology assessment. The venture valuation was performed for three jurisdictions (countries) – Singapore, the Netherlands and the United States – in order to show the opportunities in a small, medium-sized, and large country (i.e. population).ResultsThe business model assessment revealed that B2C telemonitoring is viable and profitable in the Innovating in Healthcare Framework. Analysis of the ecosystem revealed an average-to-excellent fit with the six factors. The structure and financing fit was average, public policy and technology alignment was good, while consumer alignment and accountability fit was deemed excellent. The financial prognosis revealed that the venture is viable and profitable in Singapore and the Netherlands but not in the United States due to relatively high salary inputs.ConclusionsThe B2C model in telemonitoring CHF potentially creates value for patients, shareholders of the service provider, and society. However, the validity of the results could be improved, for instance by using a peer-reviewed framework, a systematic literature search, case-based cost/efficiency inputs, and varied scenario inputs.

The Cost-Effectiveness Analysis of Philips Motiva Telehealth System: A Comparison Between Home Telemonitoring, Nurse Telephone Support And Usual Care In Chronic Heart Failure.

markdownabstractObjectives The clinical effectiveness of Motiva Monitor platform was established in the previous study (TEN-HMS). Patients randomly assigned to receive Usual Care had higher one year mortality (45%) than patients assigned to receive Nurse Telephone Support (27%) or Home Telemonitoring (29%) (p=0.032). Our intention is to provide insights in the cost-effectiveness of Motiva telehealth system by modeling the intervention and running the analysis on top of the reported data. Methods Effectiveness was established by mining the EuroQol-5D from the original database, while the information on costs came from the literature and the manufacturer of the equipment. Direct healthcare costs considered ER visits, GP, Specialist, Hospitalist and Nurse time and resources utilization. The induced (indirect) costs were not considered in the analysis. The approximation of the cost of medical consumption came from the Netherlands only, although the original study was run in three European countries. We assumed the payer perspective for our analysis. Results The results clearly show, within the parameters of our model, the increased effectiveness of Home Telemonitoring and Nurse Telephone Support in comparison to the Usual Care. The deterministic results show ICERs of € 14.842 and € 12.547 per QALY (discounted at 1.5% a year) for HTM and NTS respectfully. Probabilistic results show that NTS was the most effective strategy in health systems that pay more than €12.500 per QALY. In the subgroup analysis HTM dominated both NTS and UC at the threshold of €16.500 in NYHA IV group of Chronic Heart Failure patients. Conclusions Home telemonitoring by Motiva Monitor system reduces mortality and lowers the in-hospital length of stay. On the quality of life dimensions, Home Telemonitoring was similarly effective as the Nurse Telephone Support, but with more costs. The cost-effectiveness analysis shows that both NTS and HTM dominate the Usual Care at WTP of €15.000.

Algebraic specification of dynamic leader election protocols in broadcast networks

The problem of leader election in distributed systems is considered. Components communicate by means of buffered broadcasting as opposed to usual point-to-point communication. In this paper three leader election protocols of increasing maturity are specified. We start with a simple leader election protocol, where an initial leader is present. In the second protocol this assumption is dropped. Eventually a fault-tolerant protocol is constructed, where components may crash and revive spontaneously.

Cost-Effectiveness Analysis in Telehealth: A Comparison between Home Telemonitoring, Nurse Telephone Support, and Usual Care in Chronic Heart Failure Management

OBJECTIVES To assess the cost effectiveness of home telemonitoring (HTM) and nurse telephone support (NTS) compared with usual care (UC) in the management of patients with chronic heart failure, from a third-party payers perspective. METHODS We developed a Markov model with a 20-year time horizon to analyze the cost effectiveness using the original study (Trans-European Network-Home-Care Management System) and various data sources. A probabilistic sensitivity analysis was performed to assess the decision uncertainty in our model. RESULTS In the original scenario (which concerned the cost inputs at the time of the original study), HTM and NTS interventions yielded a difference in quality-adjusted life-years (QALYs) gained compared with UC: 2.93 and 3.07, respectively, versus 1.91. An incremental net monetary benefit analysis showed €7,697 and €13,589 in HTM and NTS versus UC at a willingness-to-pay (WTP) threshold of €20,000, and €69,100 and €83,100 at a WTP threshold of €80,000, respectively. The incremental cost-effectiveness ratios were €12,479 for HTM versus UC and €8,270 for NTS versus UC. The current scenario (including telenurse cost inputs in NTS) yielded results that were slightly different from those for the original scenario, when comparing all New York Heart Association (NYHA) classes of severity. NTS dominated HTM, compared with UC, in all NYHA classes except NYHA IV. CONCLUSIONS This modeling study demonstrated that HTM and NTS are viable solutions to support patients with chronic heart failure. NTS is cost-effective in comparison with UC at a WTP of €9000/QALY or higher. Like NTS, HTM improves the survival of patients in all NYHA classes and is cost-effective in comparison with UC at a WTP of €14,000/QALY or higher.

Early warning systems for the management of chronic heart failure: a systematic literature review of cost-effectiveness models

ABSTRACT Introduction: Describing the general and methodological characteristics of decision-analytical models used in the economic evaluation of early warning systems for the management of chronic heart failure patients and performing a quality assessment of their methodological characteristics is expected to provide concise and useful insight to inform the future development of decision-analytical models in the field of heart failure management. Areas covered: The literature on decision-analytical models for the economic evaluation of early warning systems for the management of chronic heart failure patients was systematically reviewed. Nine electronic databases were searched through the combination of synonyms for heart failure and sensitive filters for cost-effectiveness and early warning systems. Expert commentary: The retrieved models show some variability with regards to their general study characteristics. Overall, they display satisfactory methodological quality, even though some points could be improved, namely on the consideration and discussion of any competing theories regarding model structure and disease progression, identification of key parameters and the use of expert opinion, and uncertainty analyses. A comprehensive definition of early warning systems and further research under this label should be pursued. To improve the transparency of economic evaluation publications, authors should make available detailed technical information regarding the published models.