Propensity Score Matching in Randomized Clinical Trials

Cluster randomization trials with relatively few clusters have been widely used in recent years for evaluation of health-care strategies. On average, randomized treatment assignment achieves balance in both known and unknown confounding factors between treatment groups, however, in practice investigators can only introduce a small amount of stratification and cannot balance on all the important variables simultaneously. The limitation arises especially when there are many confounding variables in small studies. Such is the case in the  INSTINCT  trial designed to investigate the effectiveness of an education program in enhancing the tPA use in stroke patients. In this article, we introduce a new randomization design, the balance match weighted (BMW) design, which applies the optimal matching with constraints technique to a prospective randomized design and aims to minimize the mean squared error (MSE) of the treatment effect estimator. A simulation study shows that, under various confounding scenarios, the BMW design can yield substantial reductions in the MSE for the treatment effect estimator compared to a completely randomized or matched-pair design. The BMW design is also compared with a model-based approach adjusting for the estimated propensity score and Robins-Mark-Newey E-estimation procedure in terms of efficiency and robustness of the treatment effect estimator. These investigations suggest that the BMW design is more robust and usually, although not always, more efficient than either of the approaches. The design is also seen to be robust against heterogeneous error. We illustrate these methods in proposing a design for the  INSTINCT  trial.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78638/1/j.1541-0420.2009.01364.x.pd

Is there still a role for treatment with beta-adrenoceptor antagonists in post-myocardial infarction patients with well-preserved left ventricular systolic function?

The utility of β-adrenoceptor antagonists post myocardial infarction was established in the pre-thrombolytic era. Evidence for improvement in long-term prognosis with metoprolol, timolol and propranolol in particular derives from reduction in event rates in patients who have had substantial left ventricular damage at the time of infarction and probably correlates largely with the more recently demonstrated salutary effects of this group of drugs in patients with chronic heart failure. In all other respects, evidence for beneficial effects of β-adrenoceptor antagonists in peri-infarct and post-infarct therapeutics is equivocal. They appear to exert no major influence on outcomes in patients with unstable angina, nor do they markedly alter early clinical course in uncomplicated acute myocardial infarction, irrespective of other interventions. Furthermore, the limited available analyses suggest no discernible beneficial effect on long-term outcomes post-uncomplicated infarction. It is possible that in such patients, current recommendations for 'routine' long-term β-adrenoceptor blockade can no longer be justified.John D. Horowitz, Margaret A. Arstall, Christopher J. Zeitz, John F. Beltram

Translating what we know about the context of antisocial behavior into a lower prevalence of such behavior.

Although we have identified many variables that affect antisocial behavior, there is no evidence that we have learned how to reduce the incidence of such behavior or the proportion of young people who repeatedly engage in antisocial behavior. It is appropriate, therefore, for behavioral scientists to turn some of their energies to research on reducing the incidence and prevalence of antisocial behavior. Small communities may be a particularly useful social unit in which to conduct experimental research. The interventions to be tested include advocacy and community organizing to influence communities to make validated school and clinical interventions widely available and to assist them in increasing other forms of supervision of young people and social and material support of families. Key components of advocacy and community organizing are suggested, and possibilities for research are described

Saving lives, money and resources: drug and CABG/PCI use after myocardial infarction in a Swedish record-linkage study

Myocardial infarction, Hospital costs, Out-patient costs, Drug costs, Record linkage, I00, I18,