Right anterior thoracotomy aortic valve replacement is associated with less cost than sternotomy-based approaches: a multi-institution analysis of ‘real world’ data

Background:

Large institutional analyses demonstrating outcomes of right anterior mini-thoracotomy (RAT) for isolated aortic valve replacement (isoAVR) do not exist. In this study, a group of cardiac surgeons who routinely perform minimally invasive isoAVR analyzed a cross-section of US hospital records in order to analyze outcomes of RAT as compared to sternotomy.

Methods:

The Premier database was queried from 2007–2011 for clinical and cost data for patients undergoing isoAVR. This de-identified database contains billing, hospital cost, and coding data from >600 US facilities with information from >25 million inpatient discharges. Expert rules were developed to identify patients with RAT and those with any sternal incision (aStern). Propensity matching created groups adjusted for patient differences. The impact of surgical approach on outcomes and costs was modeled using regression analysis and, where indicated, adjusting for hospital size and geographical differences.

Results:

AVR was performed in 27,051 patients. Analysis identified isoAVR by RAT (n?=?1572) and by aStern (n?=?3962). Propensity matching created two groups of 921 patients. RAT was more likely performed in southern hospitals (63% vs 36%; p?p?p?p?p?Conclusions:

Outcomes analyses can be performed from hospital administrative collective databases. This real world analysis demonstrates comparable outcomes and less cost and ICU time with RAT for AVR.     

The Vietnam reforms,change in wage inequality and the role of the minimum wage

The Vietnam ‘renovation’ reforms were implemented during the 1990s, but their full effect was only felt several years later. We present evidence on the developments in real wage growth and inequality in Vietnam from 1998 to 2008. Using a variety of approaches (traditional measures of inequality, comparison of density functions, decomposition of the change in real wage by sector as well as a detailed decomposition of the change in the Gini), we present a consistent picture: contrary to what one might have expected given the nature of the reforms, inequality declined sharply in the private sector (but not in the state sector). This study links these developments to the policy of aggressively increasing the minimum wage over the past several years, differences in implementation by sector as well as variation in the over‐time changes in minimum wage.     

The contagion effect of default risk insurer downgrades: The impact on insured municipal bonds

Municipal bonds are often insured by insurance companies that promise to pay investors in the event of default on the part of the issuer. However, just as the financial strength of the insurer can provide assurance to investors, questions about insurer stability may heighten investor concerns. This paper considers three major downgrades to large municipal bond insurers and the effects of each downgrade on a large sample of municipal bonds. Results reveal the effects to be widespread: not only are risk premiums on bonds insured by the downgraded insurer affected, but so are those on bonds insured by other insurance companies.     

Repeated Protection for Sale

This paper addresses whether the efficient equilibria characterized by Grossman and Helpman's one‐shot protection‐for‐sale game are renegotiation‐proof in an infinitely repeated setting. We propose a simple strategy profile that can support the efficient, truthful equilibrium in each period as a strongly renegotiation‐proof subgame perfect equilibrium. This result provides another plausible reason to explain why the truthful equilibrium may be focal in the game of protection‐for‐sale. In addition, when the timing of the contributions is specified explicitly, the special interest groups should minimize the upfront payment to the government before policy implementation to reduce the possibility of the collapse of such relational contracts.     

Evaluating brand extensions,fit perceptions and post-extension brand image: does size matter?

Abstract

This study contributes to the scant literature considering brand extensions in a competitive context and investigates whether the correlation between consumers’ beliefs about a brand’s attributes and the number of its buyers described in previous research occurs with regard to fit perceptions of brand extensions, extension evaluation and post-extension brand image. In a scenario experiment with real brands and fictitious extensions, members of a commercial UK panel evaluated high and low-fit extensions and post-extension brand images of competing brands of pet food. The relative size of each brand in terms of the number of its buyers was used as a benchmark in the analysis. For all extensions, results reveal a positive correlation between post-extension brand images, extension evaluations, fit perceptions and the number of brand buyers. Results have implications for interpreting consumers’ perceptions of fit, evaluation of extensions and post-extension brand images of competing brands.     

Assessing the performance of symmetric and asymmetric implied volatility functions

This study examines several alternative symmetric and asymmetric model specifications of regression-based deterministic volatility models to identify the one that best characterizes the implied volatility functions of S&P 500 Index options in the period 1996–2009. We find that estimating the models with nonlinear least squares, instead of ordinary least squares, always results in lower pricing errors in both in- and out-of-sample comparisons. In-sample, asymmetric models of the moneyness ratio estimated separately on calls and puts provide the overall best performance. However, separating calls from puts violates the put-call-parity and leads to severe model mis-specification problems. Out-of-sample, symmetric models that use the logarithmic transformation of the strike price are the overall best ones. The lowest out-of-sample pricing errors are observed when implied volatility models are estimated consistently to the put-call-parity using the joint data set of out-of-the-money options. The out-of-sample pricing performance of the overall best model is shown to be resilient to extreme market conditions and compares quite favorably with continuous-time option pricing models that admit stochastic volatility and random jump risk factors.     

A Major Environmental Tax Reform for the UK: Results for the Economy,Employment and the Environment

This paper reports the results of a major modelling exercise to gain insights into the possible economic and environmental effects of a large-scale environmental tax reform (ETR) in the UK. ETR involves a shift in the target of taxation away from labour or firms towards pollution or the use of natural resources, in such a way that overall tax revenues are unchanged. It is hoped that such a tax shift will deliver environmental improvements while having a neutral or positive effect on the economy. The modelling was set up to explore the extent to which this would be the case. The paper starts with a brief literature review identifying the theoretical hypotheses relating to ETR and summarising the results of some of the evaluations of ETRs that have been implemented. It then briefly describes the model used for the analysis in this paper. The main body of the paper then describes the scenarios set up to explore the main impacts and the results of modelling these scenarios. These results suggest that substantial reductions in greenhouse gas (GHG) emissions can be achieved with minimal impacts on output and an overall increase in employment, such that ETR emerges as a very attractive policy for GHG emission reduction.