Cost-minimization comparison of darunavir plus ritonavir and lopinavir/ritonavir in HIV-1 infected treatment-naïve women of childbearing age

Background:

Guidelines from the Department of Health and Human Services in the US recommend ritonavir-boosted lopinavir (LPV/r) as a preferred protease inhibitor (PI) for HIV-positive antiretroviral-na?ve pregnant women. These guidelines also cite ritonavir-boosted darunavir (DRV?+?RTV) as an alternative PI in this clinical scenario. The purpose of this analysis was to compare economic outcomes for regimens based on these two treatments.

Study design:

An existing discrete event simulation (DES) model was adapted to conduct a cost-minimization analysis comparing the two regimens in HIV-infected women of childbearing age (WOCBA), from the perspective of a healthcare payer in the US.

Methods:

The DES model was used to represent disease states, health events, healthcare encounters, pregnancy, and treatment choices in HIV-infected WOCBA starting treatment with regimens based on either LPV/r or DRV?+?RTV. It also incorporated parameters for individual patient characteristics, and for antiretroviral (ARV) treatment effectiveness, treatment sequencing, clinical progression, and resource use. Potential events included scheduled physician visits; viral suppression; viral rebound; AIDS-related complications; CHD events; treatment discontinuation and switching; ARV treatment side-effects (SE); and death. The primary outcomes were discounted 5-year and 10-year healthcare costs. Alternative scenarios considered different rates of switching from DRV?+?RTV to LPV/r upon conception.

Results:

Compared with DRV?+?RTV, LPV/r was associated with similar clinical outcomes while offering savings at the 5- and 10-year horizons (of $24,904 and $43,502 per patient, respectively), and in extensive sensitivity analyses. The main driver of the savings was the difference in cost between PIs.

Conclusions:

Starting HIV-infected ARV-treatment-na?ve WOCBA on an LPV/r-based regimen is cost-saving and provides similar patient outcomes compared to a DRV?+?RTV-based regimen.     

Value creation and value capture with frictions

We use a formal value‐based model to study how frictions—incomplete linkages in the industry value chain that keep some parties from meeting and transacting—affect value creation and value capture. Frictions arise from search and switching costs and moderate the intensity of industry rivalry and the efficiency of the market. We find that firms with a competitive advantage prefer industries with less, but not zero, frictions. We show that rivalry interacts nontrivially with other competitive forces to affect industry attractiveness. Firm heterogeneity emerges naturally when we introduce resource development. Heterogeneity falls with frictions, but the sustainability of competitive advantage increases. Overall, we show that introducing frictions makes value‐based models very effective at integrating analyses at the industry, firm, and resource levels. Copyright © 2011 John Wiley & Sons, Ltd.     

The optimal capital structure of the firm with stable Lévy assets returns

This article builds a new structural default model under the assumption that a firm’s assets return follows a dynamics displaying jumps of both signs. In essence, we expand the work of Hilberink and Rogers (itself an extension of the Leland and Toft framework), which deals only with negative jumps. In contrast, we make use of stable Lévy processes, and we compute the values of the firm, debt and equity under this assumption. Theoretical credit spreads can also be obtained in our framework. They prove to be consistent with the empirical credit spreads observed in financial markets.      

Simulating the Effect of Regulatory Systems in a Fishery, An Application to the French Driftnet Albacore Fleet

With a thin economic component, most bio-economic models of fisheries failto assess the effects of the regulation systems on firms. In order to analysethe short term consequences of different management schemes, a simulationmodel is applied to the French driftnet albacore fleet: licence allocation withdriftnet regulation, individual quotas, and individual transferable quotaswithout any input control. Vessel technology is estimated by using the datacollected, and groups of vessels are distinguished according to criteria ofperformance. We present the adjustment within firms and between groupsunder different scenarios (limited entry with and without driftnetregulation, individual quotas and individual transferable quotas allocation),and we compare their results in terms of quasi-rent value and otherindicators such as hake harvests or dolphin by-catches.     

Capacity constraints, mergers and collusion

The objective of this paper is two-fold: to contribute to the analysis of tacit collusion in Bertrand supergames with (asymmetric) capacity constraints and, from a more applied perspective, to bring a new light on merger analysis and provide useful guidelines for competition policy, taking into account dynamic aspects of competition. It is well-known that capacity constraints affect tacit collusion, as they limit both incentives to deviate (e.g., to undercut rivals) and retaliation possibilities. However, most studies have so far focused on symmetric situations, where all firms have the same capacity, which leads to ambiguous and unintuitive results and also considerably limits the scope of application. Studying asymmetric situations makes it possible to analyse the impact of changes in the distribution of these capacities (expansions, but also mergers, split-offs, transfers, etc.) and to provide guidelines for competition policy and particularly for merger policy. These guidelines, which differ substantially from those inspired by more static analyses, such as the Herfindahl or other standard concentration tests, are applied to a famous merger that took place in the French bottled water market, the Nestlé-Perrier merger case.     

Collective female labour supply: theory and application

This article deals with female labour supply in the collective framework. It studies married couples and starting from the empirical observation that the husband's labour supply is generally fixed at full-time. It shows that, in this case, structural elements of the decision process, such as individual preferences or the rule that determines the intra-household distribution of welfare, can be identified if household demand for at least one commodity, together with the wife's labour supply, is observed. These theoretical considerations are followed by an application using French data.     

GARCH models without positivity constraints: Exponential or log GARCH?

This paper provides a probabilistic and statistical comparison of the log-GARCH and EGARCH models, which both rely on multiplicative volatility dynamics without positivity constraints. We compare the main probabilistic properties (strict stationarity, existence of moments, tails) of the EGARCH model, which are already known, with those of an asymmetric version of the log-GARCH. The quasi-maximum likelihood estimation of the log-GARCH parameters is shown to be strongly consistent and asymptotically normal. Similar estimation results are only available for the EGARCH (1,1) model, and under much stronger assumptions. The comparison is pursued via simulation experiments and estimation on real data.