Assessing the effectiveness of primary angioplasty compared with thrombolysis and its relationship to time delay: a Bayesian evidence synthesis

Background: Meta-analyses of trials have shown greater benefits from angioplasty than thrombolysis after an acute myocardial infarction, but the time delay in initiating angioplasty needs to be considered. Objective: To extend earlier meta-analyses by considering 1- and 6-month outcome data for both forms of reperfusion. To use Bayesian statistical methods to quantify the uncertainty associated with the estimated relationships. Methods: A systematic review and meta-analysis published in 2003 was updated. Data on key clinical outcomes and the difference between time-to-balloon and time-to-needle were independently extracted by two researchers. Bayesian statistical methods were used to synthesise evidence despite differences between reported follow-up times and outcomes. Outcomes are presented as absolute probabilities of specific events and odds ratios (ORs; with 95% credible intervals (Crl)) as a function of the additional time delay associated with angioplasty. \ Results: 22 studies were included in the meta-analysis, with 3760 and 3758 patients randomised to primary angioplasty and thrombolysis, respectively. The mean ( SE) angioplasty-related time delay ( over and above time to thrombolysis) was 54.3 (2.2) minutes. For this delay, mean event probabilities were lower for primary angioplasty for all outcomes. Mortality within 1 month was 4.5% after angioplasty and 6.4% after thrombolysis ( OR = 0.68 ( 95% Crl 0.46 to 1.01)). For non-fatal reinfarction, OR = 0.32 ( 95% Crl 0.20 to 0.51); for non-fatal stroke OR = 0.24 ( 95% Crl 0.11 to 0.50). For all outcomes, the benefit of angioplasty decreased with longer delay from initiation. Conclusions: The benefit of primary angioplasty, over thrombolysis, depends on the former's additional time delay. For delays of 30-90 minutes, angioplasty is superior for 1- month fatal and non-fatal outcomes. For delays of around 90 minutes thrombolysis may be the preferred option as assessed by 6-month mortality; there is considerable uncertainty for longer time delays

Effect of age on the prognostic value of left ventricular function in patients with acute coronary syndrome:a prospective registry study

Objective: This study aims to study the prognostic impact of LV function on mortality and examine the effect of age on the prognostic value of left ventricular function.  Methods: We examined the Myocardial Ischaemia National Audit Project (MINAP) registry (2006-2010) data with a mean follow up of 2.1 years. LV function was categorized into good (ejection fraction (EF) ≥50%), moderate (EF 30-49%) and poor (EF <30%) categories. Cox-proportional hazards models were constructed to examine the prognostic significance of LV function in different age groups (<65, 65-74, 75-84 and ≥85 years) on all-cause mortality adjusting for baseline variables.  Results: Of 424,848 patients, LV function data available for 123,609. Multiple imputations were used to impute missing values of LV function and the final sample for analyses were drawn from 414,305. After controlling for confounders, 339,887 participants were included in the regression models. For any age group, mortality was higher with worsening degree of LV impairment. Increased age reduced the adverse prognosis associated with reduced LV function (hazard ratios (HRs) of death comparing poor LV function to good LV function were 2.11 95%CI 1.88-2.37 for age <65 years and 1.28 95%CI 1.20-1.36 for age ≥85 years. Older patients had a high mortality risk even in those with good LV function. HRs of mortality for ≥85 compared to <65 years (HR=1.00) within good, moderate and poor ejection fractions groups were 5.89, 4.86 and 3.43, respectively.  Conclusions: In patients with ACS, clinicians should interpret the prognostic value of LV function taking into account patient’s age

A semiparametric bivariate probit model for joint modeling of outcomes in STEMI patients

In this work we analyse the relationship among in-hospital mortality and a treatment effectiveness outcome in patients affected by ST-Elevation myocardial infarction. The main idea is to carry out a joint modeling of the two outcomes applying a Semiparametric Bivariate Probit Model to data arising from a clinical registry called STEMI Archive. A realistic quantification of the relationship between outcomes can be problematic for several reasons. First, latent factors associated with hospitals organization can affect the treatment efficacy and/or interact with patient’s condition at admission time. Moreover, they can also directly influence the mortality outcome. Such factors can be hardly measurable. Thus, the use of classical estimation methods will clearly result in inconsistent or biased parameter estimates. Secondly, covariate-outcomes relationships can exhibit nonlinear patterns. Provided that proper statistical methods for model fitting in such framework are available, it is possible to employ a simultaneous estimation approach to account for unobservable confounders. Such a framework can also provide flexible covariate structures and model the whole conditional distribution of the response

Automatic covariate selection in logistic models for chest pain diagnosis: A new approach

A newly established method for optimizing logistic models via a minorization-majorization procedure is applied to the problem of diagnosing acute coronary syndromes (ACS). The method provides a principled approach to the selection of covariates which would otherwise require the use of a suboptimal method owing to the size of the covariate set. A strategy for building models is proposed and two models optimized for performance and for simplicity are derived via ten-fold cross-validation. These models confirm that a relatively small set of covariates including clinical and electrocardiographic features can be used successfully in this task. The performance of the models is comparable with previously published models using less principled selection methods. The models prove to be portable when tested on data gathered from three other sites. Whilst diagnostic accuracy and calibration diminishes slightly for these new settings, it remains satisfactory overall. The prospect of building predictive models that are as simple as possible for a required level of performance is valuable if data-driven decision aids are to gain wide acceptance in the clinical situation owing to the need to minimize the time taken to gather and enter data at the bedside

Traffic particles and occurrence of acute myocardial infarction: a case–control analysis

OBJECTIVES: We modelled exposure to traffic particles using a latent variable approach and investigated whether long-term exposure to traffic particles is associated with an increase in the occurrence of acute myocardial infarction (AMI) using data from a population-based coronary disease registry. METHODS: Cases of individually validated AMI were identified between 1995 and 2003 as part of the Worcester Heart Attack Study. Population controls were selected from Massachusetts, USA, resident lists. NO(2) and PM(2.5) filter absorbance were measured at 36 locations throughout the study area. The air pollution data were used to estimate exposure to traffic particles using a semiparametric latent variable regression model. Conditional logistic models were used to estimate the association between exposure to traffic particles and occurrence of AMI. RESULTS: Modelled exposure to traffic particles was highest near the city of Worcester. Cases of AMI were more exposed to traffic and traffic particles compared to controls. An interquartile range increase in modelled traffic particles was associated with a 10% (95% CI 4% to 16%) increase in the odds of AMI. Accounting for spatial dependence at the census tract, but not block group, scale substantially attenuated this association. CONCLUSIONS: These results provide some support for an association between long-term exposure to traffic particles and risk of AMI. The results were sensitive to the scale selected for the analysis of spatial dependence, an issue that requires further investigation. The latent variable model captured variation in exposure, although on a relatively large spatial scale

The Impact of Medical Liability Standards on Regional Variations in Physician Behavior: Evidence from the Adoption of National-Standard Rules

I explore the association between regional variations in physician behavior and the geographical scope of malpractice standards of care. I estimate a 30–50 percent reduction in the gap between state and national utilization rates of various treatments and diagnostic procedures following the adoption of a rule requiring physicians to follow national, as opposed to local, standards. These findings suggest that standardization in malpractice law may lead to greater standardization in practices and, more generally, that physicians may indeed adhere to specific liability standards. In connection with the estimated convergence in practices, I observe no associated changes in patient health

Craniofacial pain of cardiac origin : an Interdisciplinary Study

Referred pain is frequently associated with misdiagnosis and unnecessary therapy directed to the pain location instead of its origin. When craniofacial pain is the sole symptom of myocardial ischemia, failure to recognize its cardiac source can endanger the patient. In particular, patients with acute myocardial infarction (AMI) who do not experience chest pain run a very high risk of misdiagnosis and death. Pain that is limited to the craniofacial region during myocardial ischemia has so far been described only in case reports and its overall prevalence is unknown. Experimental research in animals suggests a vagal involvement in the pathological mechanisms of cardiac pain referred to the face. The aim of this study was to gain knowledge about the prevalence, clinical characteristics and possible mechanisms of craniofacial pain of cardiac origin, in order to improve the clinician’s ability to make a correct diagnosis. It was hypothesized that the quality of craniofacial pain from cardiac versus dental origin would differ, implying a high diagnostic validity. It was also hypothesized that craniofacial pain can be the sole symptom of a prodromal (pre-infarction) angina episode and that this pain location would be especially associated with cardiac ischemia in the areas more densely innervated by vagal afferent fibres. The study group was comprised of consecutive patients who experienced craniofacial pain of a verified cardiac (n=326) or dental (n=359) origin. Demographic details on age, gender and pain characteristics (location, quality and intensity) were assessed in both groups. Cardiovascular risk factors, cardiac diagnosis and ECG signs of ischemia were also assessed in the cardiac pain group. Ethics approval and informed consent for each patient was obtained. Craniofacial pain was found to be the sole symptom of myocardial ischemia in 6% of patients and was the sole symptom of an AMI in 4% of patients; this craniofacial pain was more prevalent in women (p=0.031). In those patients without chest pain, it was the most frequent pain location and was the only symptom of prodromal angina in 5% of AMI patients. The craniofacial pain included the throat, the jaws, the temporomandibular joints/ears and the teeth, mainly bilaterally. The pain quality descriptors “pressure” and “burning” were statistically associated with pain of cardiac origin, while “throbbing” and “aching” were associated with an odontogenic cause (p<0.001). In myocardial ischemia patients, the occurrence of craniofacial pain was associated with an inferior localization of ischemia in the heart (p<0.001). In conclusion, this study showed that pain in the craniofacial region could be the sole symptom of cardiac ischemia and AMI, particularly in women. Craniofacial pain of cardiac origin was commonly bilateral, with the quality pain descriptors “pressure” and “burning”, and pain provocation with physical activity and pain relief at rest. The association between the presence of craniofacial pain and inferior wall ischemia suggests a vagal involvement in the mechanisms of cardiac pain referred to the craniofacial region. Since the possibility of misdiagnosis and death in this group of patients is high, awareness of this clinical presentation needs to be brought to the attention of researchers, clinicians and the general public.Preface – Abstract – Abbreviations – Introduction – Objectives -- Material and Methods – Results -- Discussion – Conclusions – Acknowledgments -- Reference