Effect of hospital ownership status and payment structure on the adoption and use of drug-eluting stents for percutaneous coronary interventions

BACKGROUND: The impact of the use of drug-eluting stents in percutaneous coronary intervention (PCI) on cardiac care is still uncertain. We examined the influence of systemic factors, such as hospital ownership status, organizational characteristics and payment structure, on the use of drug-eluting stents in PCI and the effect on cardiac surgery volume. METHODS: We conducted a cross-sectional analysis of drug-eluting stent use in 12 993 patients undergoing PCI with stenting (drug-eluting or bare-metal) and time-series regression analyses of the monthly number of cardiac surgery and PCI procedures performed using data collected from 1998 to 2004 at 13 public and private hospitals in the Emilia-Romagna region of Italy. RESULTS: Public hospitals used drug-eluting stents more selectively than private hospitals, targeting the new device to patients at high risk of adverse events. The time-series regression analyses showed that the number of PCI procedures performed per year increased during this period, both in public (slope coefficient 36.4, 95% confidence interval [CI] 30.2 to 43.1) and private centres (slope coefficient 6.4, 95% CI 3.1 to 9.2 ). Concurrently, there was a reduction in the number of isolated coronary artery bypass graft (CABG) surgeries, although the degree of change was higher in public than in private hospitals (coefficient –16.1 v. –6.2 respectively ). The number of CABG procedures associated with valve surgery decreased in public hospitals (coefficient –5.0, 95% CI –6.1 to –3.8) but increased in private hospitals (coefficient 4.1, 95% CI 2.0 to 6.1). INTERPRETATION: Public and private hospitals behaved differently in adopting drug-eluting stents and in using PCI with drug-eluting stents as a substitute for surgical revascularization

Approximating Multivariate Markov Chains for Bootstrapping Through Contiguous Partitions

This paper extends Markov chain bootstrapping to the case of multivariate continuous-valued stochastic processes. To this purpose, we follow the approach of searching an optimal partition of the state space of an observed (multivariate) time series. The optimization problem is based on a distance indicator calculated on the transition probabilities of the Markov chain. Such criterion aims at grouping those states exhibiting similar transition probabilities. A second methodological contribution is represented by the addition of a contiguity constraint, which is introduced to force the states to group only if they have “near” values (in the state space). This requirement meets two important aspects: first, it allows a more intuitive interpretation of the results; second, it contributes to control the complexity of the problem, which explodes with the cardinality of the states. The computational complexity of the optimization problem is also addressed through the introduction of a novel Tabu Search algorithm, which improves both the quality of the solution found and the computing times with respect to a similar heuristic previously advanced in the literature. The bootstrap method is applied to two empirical cases: the bivariate process of prices and volumes of electricity in the Spanish market; the trivariate process composed of prices and volumes of a US company stock (McDonald’s) and prices of the Dow Jones Industrial Average index. In addition, the method is compared with two other well-established bootstrap methods. The results show the good distributional properties of the present proposal, as well as a clear superiority in reproducing the dependence among the data

Approximating Markov Chains for Bootstrapping and Simulation

In this work we develop a bootstrap method based on the theory of Markov chains. The method moves from the two competing objectives that a researcher pursues when performing a bootstrap procedure: (i) to preserve the structural similarity – in statistical sense – between the original and the bootstrapped sample; (ii) to assure a diversification of the latter with respect to the former. The original sample is assumed to be driven by a Markov chain. The approach we follow is to implement an optimization problem to estimate the memory of a Markov chain (i.e. its order) and to identify its relevant states. The basic ingredients of the model are the transition probabilities, whose distance is measured through a suitably defined functional. We apply the method to the series of electricity prices in Spain. A comparison with the Variable Length Markov Chain bootstrap, which is a well established bootstrap method, shows the superiority of our proposal in reproducing the dependence among data

Adherence to agents acting on the renin-angiotensin system in secondary prevention of non-fatal myocardial infarction: a self-controlled case-series study

In accordance with current guidelines, patients discharged after acute myocardial infarction (AMI) are usually prescribed agents acting on the renin-angiotensin system (ACE-I/ARB). However, adherence to prescribing medications is a recognized problem and most studies demonstrating the value of adherence were limited by their non-randomized design and by 'healthy-adherer' bias. Herein we sought to evaluate the relationship between adherence to ACE-I/ARB and risk of subsequent AMIs, by using the self-controlled case-series design which virtually eliminates interpersonal confounding, being based on intrapersonal comparisons

Comparison of 2-year clinical outcomes with sirolimus and paclitaxel-eluting stents for patients with diabetes: Results of the REgistro regionale AngiopLastiche Emilia-Romagna registry

Background: Long-term outcomes of percutaneous coronary interventions (PCI) with sirolimus-eluting stents (SES) compared to paclitaxel-eluting-stents (PES) in unselected diabetics in routine practice is still debated. Objective: This study compared the 2-year incidence of MACE (all-cause mortality, nonfatal myocardial infarction and target vessel revascularization) of SES and PES in a real-world setting of patients with diabetes. Design: Observational, multicenter, nonrandomized study. Setting: Prospective web-based registry (REAL Registry; study period, 2002-2005) comprising all 13 hospitals performing PCI. Patients: Among the 945 eligible patients treated with either SES alone (n = 606) or PES alone (n = 339), 29% were insulin-requiring, 72% had multivessel coronary disease, 26% had prior myocardial infarction and 10% had poor left ventricular function. Measurements: Unadjusted and propensity score-adjusted 2-year clinical outcome. Results: After propensity score adjustment, 2-year MACE incidence in the SES and PES groups was equivalent (23.3% vs. 23.7%, HR 1.01, 95%CI 0.72-1.42, P = 0.96). Adjusted 2-year angiographic stent thrombosis occurred in 1.1% of the SES patients versus 2.6% of the PES patients (P = 0.15). In this large, real-world, diabetic population treated with DES, there was no difference in outcome between SES and PES. Further studies are needed to demonstrate the long-term safety of different types of DES in patients with diabetes. © 2009 Wiley-Liss, Inc

Risk of Adverse Cardiac and Bleeding Events Following Cardiac and Noncardiac Surgery in Patients with Coronary Stent: How Important Is the Interplay between Stent Type and Time from Stenting to Surgery?

Background - Epidemiology and consequences of surgery in patients with coronary stents are not clearly defined, as well as the impact of different stent types in relationship with timing of surgery. Methods and Results - Among 39 362 patients with previous coronary stenting enrolled in a multicenter prospective registry and followed for 5 years, 13 128 patients underwent 17 226 surgical procedures. The cumulative incidence of surgery at 30 days, 6 months, 1 year, and 5 years was 3.6%, 9.4%, 14.3%, and 40.0%, respectively, and of cardiac and noncardiac surgery was 0.8%, 2.1%, 2.6%, and 4.0% and 1.3%, 5.1%, 9.1%, and 31.7%, respectively. We assessed the incidence and the predictors of cardiac death, myocardial infarction, and serious bleeding event within 30 days from surgery. Cardiac death occurred in 438 patients (2.5%), myocardial infarction in 256 (1.5%), and serious bleeding event in 1099 (6.4%). Surgery increased 1.58× the risk of cardiac death during follow-up. Along with other risk factors, the interplay between stent type and time from percutaneous coronary intervention to surgery was independently associated with cardiac death/myocardial infarction. In comparison with bare-metal stent implanted >12 months before surgery, old-generation drug-eluting stent was associated with higher risk of events at any time point. Conversely, new-generation drug-eluting stent showed similar safety as bare-metal stent >12 months and between 6 and 12 months and appeared trendly safer between 0 and 6 months. Conclusions - Surgery is frequent in patients with coronary stents and carries a considerable risk of ischemic and bleeding events. Ischemic risk is inversely related with time from percutaneous coronary intervention to surgery and is influenced by stent type