Axelrod's metanorm games on networks.

Metanorms is a mechanism proposed to promote cooperation in social dilemmas. Recent experimental results show that network structures that underlie social interactions influence the emergence of norms that promote cooperation. We generalize Axelrod's analysis of metanorms dynamics to interactions unfolding on networks through simulation and mathematical modeling. Network topology strongly influences the effectiveness of the metanorms mechanism in establishing cooperation. In particular, we find that average degree, clustering coefficient and the average number of triplets per node play key roles in sustaining or collapsing cooperation.

Long term medical and economical benefit of machine perfusion (MP) kidney storage in comparison to cold storage (CS).

BACKGROUND: Despite documented positive effect of MachinePerfusion (MP) on long-term kidneys-graft function its wide use is restricted due to higher costs. The aim of this study was to analyze the difference in costs of kidney transplantation in patients who received organ stored in ColdStorage (CS) vs those who received kidneys stored with MP.
MATERIAL/METHODS: Analysis was done on kidney transplantations performed between 1994-1999 in 415 patients.. Kidneys were not randomized to MP or to CS: 188 kidneys were stored in CS, 227-in MP. Recipients didn't differ in regard to the age, sex, PRA, HLA mismatch, and immunosupression.The costs of organ procurement,transportation,surgical and anesthetic procedures, episodes of acute rejection were similar for both group of patients and were not included into the analysis. Costs of first month post-transplantation included: the cost of MP, post-transplantation hemodialysis, costs of hospitalization.Analysis of costs difference in between two groups of patients during follow-up included the costs of immunosupression and the monthly cost of dialysis. Statistical analysis was done using linear regression model.
RESULTS: Long graft survival was 68,2% in MP group vs.54,2% in CS group (p=0.02) Return to dialysis treatment was 20% in MP group vs.36% in CS group (p=0.01).Since 2 month post-transplant, mean cost of treatment for one patient was higher of 59,7 USD in CS group vs. MP group (p<0.001)in each month. Costs of investments on MP were equalized in 16 month post-transplantation.
CONCLUSIONS: Despite higher costs of MP use in the first month post transplantation, it is money-saving method of kidneys preservation and its cost of use, are equalized after 16 months post transplantation.

The cost comparison of rhythm and rate control strategies in persistent atrial fibrillation.

UNLABELLED: Our sub study was designed to analyze the cost effectiveness of two alternative treatment strategies with a view to improved allocation of the limited therapeutic resources. To that effect we conducted detailed analysis of the related costs and other relevant data collected in the course of the HOT CAFE study. METHODS: The prospective costs related to 205 patients randomly assigned to rhythm or rate control were traced over a 12 month period. Since, both strategies produced similar clinical outcomes a cost minimization analysis was undertaken. The cost of diagnostic and treatment procedures, including hospitalization, outpatient visits, drugs and physicians consultations were estimated for both groups. RESULTS: The study population comprised 205 patients (mean age 60.8 year; 35% females). A hundred and one patients were randomly assigned to the rate control group with the pharmacological heart rate frequency optimization treatment combined with Holter monitoring. A hundred and four patients were randomized to sinus rhythm (SR) restoration with its subsequent maintenance with sequential antiarrhythmic drug treatment. There was no significant difference in the composite primary end-point (all-cause mortality, number of thromboembolic and major bleeding events). The hospital admissions rate was significantly higher in the rhythm control than the rate control arm (202 vs. 5, respectively). The conservative strategy involving pharmacological ventricular rate control proved to be less costly than rhythm control (1225 euros vs. 2526 euros; p<0.001). The main cost driver behind the established difference was the cardioversion related hospitalization. CONCLUSIONS: The cost effectiveness appraisal seems to have supported the rate control strategy as less costly due to the lower hospitalization rate as a major cost carrier.