Determinants of variations in coronary revascularization practices

Background:

The ratio of percutaneous coronary interventions to coronary artery bypass graft surgeries (PCI:CABG ratio) varies considerably across hospitals. We conducted a comprehensive study to identify clinical and nonclinical factors associated with variations in the ratio across 17 cardiac centres in the province of Ontario.

Methods:

In this retrospective cohort study, we selected a population-based sample of 8972 patients who underwent an index cardiac catheterization between April 2006 and March 2007 at any of 17 hospitals that perform invasive cardiac procedures in the province. We classified the hospitals into four groups by PCI:CABG ratio (low [< 2.0], low–medium [2.0–2.7], medium–high [2.8–3.2] and high [> 3.2]). We explored the relative contribution of patient, physician and hospital factors to variations in the likelihood of patients receiving PCI or CABG surgery within 90 days after the index catheterization.

Results:

The mean PCI:CABG ratio was 2.7 overall. We observed a threefold variation in the ratios across the four hospital ratio groups, from a mean of 1.6 in the lowest ratio group to a mean of 4.6 in the highest ratio group. Patients with single-vessel disease usually received PCI (88.4%–99.0%) and those with left main artery disease usually underwent CABG (80.8%–94.2%), regardless of the hospital’s procedure ratio. Variation in the management of patients with non-emergent multivessel disease accounted for most of the variation in the ratios across hospitals. The mode of revascularization largely reflected the recommendation of the physician performing the diagnostic catheterization and was also influenced by the revascularization “culture” at the treating hospital.

Interpretation:

The physician performing the diagnostic catheterization and the treating hospital were strong independent predictors of the mode of revascularization. Opportunities exist to improve transparency and consistency around the decision-making process for coronary revascularization, most notably among patients with non-emergent multivessel disease.Large inter-regional and inter-hospital variations exist in the ratio of percutaneous coronary intervention (PCI) procedures to coronary artery bypass graft (CABG) surgeries performed in many countries, but the reasons for these variations are uncertain.^1–3 Bypass surgery was the first method of coronary revascularization to be developed.⁴ The less-invasive alternative of PCI was developed initially to treat single-vessel disease. However, advances in PCI technology (e.g., bare-metal stents and, later, drug-eluting stents) combined with increased operator experience have led to its use for a broader list of indications, including multivessel disease and acute coronary syndromes.^5–7In Ontario, Canada’s most populous province, the overall PCI:CABG ratio has steadily increased, from 1.6 in 2001 to 2.7 in 2006 (unpublished data available from the authors upon request); similar increases have been observed in other jurisdictions.^1,2,8 Although the change in ratio has been driven in part by expanded use of urgent PCI for acute myocardial infarction (MI), increased use of PCI in patients with multivessel disease has likely also been a contributing factor. This application of PCI is more controversial, because several studies, including the recent randomized SYNTAX (Synergy Between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery) trial, have shown that long-term outcomes of certain patients with multivessel disease were better with CABG surgery than with PCI.^9–13In addition to an overall increase in the PCI:CABG ratio, the amount of variation in the ratio across cardiac centres in Ontario has also steadily increased over time, with more than a threefold regional variation observed in 2006 (unpublished data available from the authors upon request). This degree of variation has raised concerns among some policy-makers and clinicians as to why such striking variations exist in Ontario’s universal health care system. To address this issue, we conducted a comprehensive study to identify clinical and nonclinical factors associated with variations in the PCI:CABG ratio across the province’s 17 cardiac centres.     

Sex-related differences in access to care among patients with premature acute coronary syndrome

Background:

Access to care may be implicated in disparities between men and women in death after acute coronary syndrome, especially among younger adults. We aimed to assess sex-related differences in access to care among patients with premature acute coronary syndrome and to identify clinical and gender-related determinants of access to care.

Methods:

We studied 1123 patients (18–55 yr) admitted to hospital for acute coronary syndrome and enrolled in the GENESIS-PRAXY cohort study. Outcome measures were door-to-electrocardiography, door-to-needle and door-to-balloon times, as well as proportions of patients undergoing cardiac catheterization, reperfusion or nonprimary percutaneous coronary intervention. We performed univariable and multivariable logistic regression analyses to identify clinical and gender-related determinants of timely procedures and use of invasive procedures.

Results:

Women were less likely than men to receive care within benchmark times for electrocardiography (≤ 10 min: 29% v. 38%, p = 0.02) or fibrinolysis (≤ 30 min: 32% v. 57%, p = 0.01). Women with ST-segment elevation myocardial infarction (MI) were less likely than men to undergo reperfusion therapy (primary percutaneous coronary intervention or fibrinolysis) (83% v. 91%, p = 0.01), and women with non–ST-segment elevation MI or unstable angina were less likely to undergo nonprimary percutaneous coronary intervention (48% v. 66%, p < 0.001). Clinical determinants of poorer access to care included anxiety, increased number of risk factors and absence of chest pain. Gender-related determinants included feminine traits of personality and responsibility for housework.

Interpretation:

Among younger adults with acute coronary syndrome, women and men had different access to care. Moreover, fewer than half of men and women with ST-segment elevation MI received timely primary coronary intervention. Our results also highlight that men and women with no chest pain and those with anxiety, several traditional risk factors and feminine personality traits were at particularly increased risk of poorer access to care.Despite improvements in the management of acute coronary syndrome over the past few decades, differences in mortality between men and women persist, especially among younger adults.¹ The reasons for poorer outcomes among women are thought to be multifactorial and may include higher baseline prevalence of risk factors for cardiovascular disease^2–4 and poorer access to care.^2–6 However, in the cited studies, patients were relatively old, and only one study⁴ considered clinical factors as potential confounders in the relationship. Moreover, determinants of access to care in men and women with premature acute coronary syndrome remain unknown.The effect of gender-related factors on access to care has not been investigated. Unlike sex, which is a biological characteristic, gender has a wider scope, incorporating the effects of social norms and expectations for men and women. Gender-related variables include gender identity, social roles, socioeconomic status and interpersonal relationships. There has been a considerable reduction in the gender gap in North America in the past decades.⁷ As a result, more women are gaining access to education and employment, and sharing of household and workplace responsibilities is becoming more common. Therefore, assessing sex alone cannot adequately account for differences in access to care among young adults with premature acute coronary syndrome. To better understand differences in access to care between men and women, a detailed examination of both sex- and gender-related factors is required.Our primary objective in this study was to assess sex-related differences in access to care among adults with premature acute coronary syndrome. Our secondary objective was to identify clinical and gender-related determinants of access to care among men and women.     

Sex-related differences in the association between plasma fibrinogen and non-calcified or mixed coronary atherosclerotic plaques

Background

Plasma fibrinogen (FIB) has been demonstrated to be a risk factor for cardiovascular disease. Patients with non-calcified plaque (NCP) or mix plaque (MP) have a higher risk of poor outcomes. However, the association between FIB and the presence of NCP or MP (NCP/MP) remains unclear, and if present, whether sex has any impact on this association remains unknown. The aim of this study was to investigate the role of FIB in predicting the presence of NCP/MP and evaluate whether sex has any impact on this association.

Methods

A total of 329 subjects were recruited, and the clinical and laboratory data were collected. Plasma FIB was detected by enzyme-linked immunosorbent assay. According to whether they had coronary atherosclerotic plaques and the characteristics of the most stenotic plaque, we divided them into three groups: no plaque (NP), calcified plaque (CP), and NCP/MP.

Results

Patients with NCP/MP had significantly higher FIB level in females, but not in males. Multiple logistic regression analysis showed that FIB was an independent risk factor for the presence of NCP/MP (odds ratio [OR]?=?3.677, 95% CI 1.539–8.785, P?=?0.003) in females. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value FIB for predicting the presence of NCP/MP was 3.41?g/L (area under curve [AUC]?=?0.73, 95% CI 0.63–0.82, P?<? 0.001) in females.

Conclusions

FIB is independently associated with the presence of NCP/MP in females, but not in males. These results suggest that the potential significance of FIB-lowering regimens in females with NCP/MP.

     

Legal implications of premenstrual syndrome: a Canadian perspective.

A summary of the symptoms, prevalence and history of premenstrual syndrome (PMS) is presented. The legal implications of PMS, particularly its use as a defence in criminal prosecutions and as an implicit factor in specific offences, are discussed by means of an analysis of Canadian legal cases, with reference to those in England and the United States. The authors offer suggestions on how physicians can make use of PMS in a courtroom more reliable. They conclude that PMS is unlikely to become a substantive criminal defence until the medical community more fully recognizes its significance. Although the role of PMS as a mitigating factor in sentencing may be illogical, the courts now recognize the syndrome in a legally and practically important manner.     

Sex-related differences in cadmium-induced lipid peroxidation in the rat

Male and female rats were dosed once a day for 2 days injection with 1.5 mg of Cd/kg as CdCl₂. 24 hr after administration of cadmium, lipid peroxidation determined by estimation of malondialdehyde (MDA) was greatly increased in male rat liver, but was not in female rats. Cadmium in a larger dose of 4.5 mg/kg, subcutaneous single injection, significantly increased content of MDA in female rat liver. These results suggest that sex-related differences exist in the ability of cadmium to induce MDA formation in rat liver, although administration of cadmium causes the enhancement of MDA formation in both male and female rats. The reason why sex-related differences exist in lipid peroxidation of rat liver is discussed.     

Sex-related differences in the regulation of macrophage cholesterol metabolism

Men have an earlier onset and higher incidence of coronary heart disease than women, independent of environmental risk factor exposure. As a consequence, there has been considerable interest in the potential role of sex hormones in atherogenesis. An emerging body of evidence suggests that sex-specific tissue and cellular characteristics may mediate sex-specific responses to a variety of stimuli. Recent studies have shown that oestrogen, progesterone and androgens all regulate processes integral to human macrophage foam cell formation, a key event in atherogenesis, in a sex-specific manner; findings that may have important implications for understanding the sex gap in atherosclerosis. Physiological levels of 17beta-estradiol and progesterone are both associated with a female-specific reduction in cholesteryl ester accumulation in human macrophages. By contrast, androgens increase cholesteryl ester formation in male but not in female donor human macrophages. This review summarizes current data concerning the sex-specific effects of sex hormones on processes important to macrophage foam cell formation and the basic mechanisms responsible for the sex specificity of such effects. Future research in this promising field may eventually lead to the novel concept of 'sex-specific' treatments directed at inhibiting atherogenesis.     

Gender-specific differences in biomarkers responses to acute coronary syndromes and revascularization procedures

A growing body of gender-related research in coronary artery disease is beginning to gradually elucidate differences between women and men. In patients presenting with acute coronary syndromes (ACS), these sex differences include varying risk factor profiles, accuracy of diagnostic testing, clinical presentations, treatment practices and outcomes. There is also a differential expression of cardiac biomarkers by sex, which remains unexplained. This paper reviews all the available information on the effect of gender on cardiac biomarkers by search of MEDLINE using the terms gender differences, biomarkers, ACS and revascularization procedures. A better understanding of the sex disparities in biomarkers along with all other clinical information is essential to optimal management and patient care in the future.     

Sex-related differences in the diet of the mink Mustela vison

The diets of free-ranging male and female mink were sampled by analysing faeces collected from radio-tagged individuals. Significant sex differences were apparent in the predation upon three of the five principal prey groups. The larger males preyed much more heavily upon lagomorphs, the largest prey taken, while females preyed more upon fish and crustaceans than did males. These differences were consistent in each season except the autumn (September to November), when males preyed more heavily upon fish and crustacea than did females. Due to their large size, adult lagomorphs are felt to be relatively unavailable to female mink. Male mink are apparently large enough to specialize on lagomorphs, and male mink niche breadth was consistently lower than that of females. Dietary overlap approximated to 40% in all seasons except summer (68%), when female predation upon lagomorphs reached a peak. This reduction in intraspecific feeding competition was felt to be a valuable side-effect of body-size dimorphism.     

Sex-related differences in the hepatobiliary transport of phenolsulfonphthalein in the rat

Sex-related differences in the hepatobiliary transport of phenolsulfonphthalein (PSP) were investigated in male and female Wistar rats. Maximal biliary excretion of unconjugated PSP was significantly higher in females while the excretion of the conjugated dye and liver UDP-glucuronosyltransferase activity toward PSP were higher in male animals. Orchidectomy decreased enzyme activity and excretion of the conjugate, whereas ovariectomy produced the opposite effect. Both in gonadectomized males and females maximal biliary excretion of the unconjugated dye was significantly reduced. Testosterone treatment increased the excretion of both conjugated and unconjugated PSP and transferase activity in orchidectomized males. Combined treatment of gonadectomized females with estradiol plus progesterone led to excretions of both conjugated and unconjugated PSP and UDP-glucoronosyltransferase activities similar to those found in control rats. These data indicate the existence of sex-related differences in the conjugation and biliary excretion of PSP in the rat and its modulation by sex hormones.     

Sex-related differences in transmission of hepatitis B infection in a Melanesian population

Factors involved in the spread of hepatitis B virus (HBV) in the largely Melanesian population (N = 909) of Graciosa Bay, Ndeni, are examined. Based upon cultural information from Ndeni and ways in which HBV is spread in other populations, certain practices and interactions, predicted as effective routes of HBV infection, are analyzed. Most significant are father-to-son transmission and older-brother-to-younger-sibling transmission, indicating that males are instrumental in the transmission of HBV on Ndeni. Other possible routes of HBV transmission that are not shown to be significant on Ndeni are significant modes of disease spread in other cultures. Cross-cultural differences are discussed with regard to behavior, age of infection, and persistence of HBeAg (an antigen linked to HBV infection). Particularly with regard to maternal transmission, it is clear that the average age of infection combined with the degree of HBeAg persistence limits the number of infective mothers in this population. Cultural practices, however, may explain the disproportion of male carriers over 30 implicating a largely extinct set of culturally sanctioned practices involving very early exposure to HBV in boys and their age-related inability to make antibody to the virus.     

Developing a Canadian prescribing practices network. Network Development Committee of the Canadian Prescribing Practices Network Project.

Expenditure on drug therapy in Canada has been growing at a faster rate than spending on any other aspect of health care. Increasing societal pressure to use scarce resources more efficiently, advances in communication technology and data indicating that there is room for improvement in drug prescribing suggest that the time has come for an organized linkage of the available drug-utilization and health-outcomes data-bases across the country. A national prescribing practices network would assist prescribers, researchers and policymakers to optimize prescribing with respect to both cost effectiveness and health outcomes. The authors outline the main concerns addressed in the 1994 report to the National Pharmaceutical Strategy and present the results of discussions by the Canadian Prescribing Practices Network Project with respect to the potential users and data sources of a national network and the communications technology on which it would rely.     

Maternal serum alpha-fetoprotein screening: report of a Canadian pilot project.

A pilot project of maternal serum alpha-fetoprotein (MSAFP) screening was carried out in Ontario from 1982 to 1985 to examine the feasibility and acceptability of screening a prenatal population for open fetal neural tube defects. A total of 8140 patients at low genetic risk were screened. Patient acceptance was excellent. Blood samples were taken at 16 to 18 weeks'' gestation. If the MSAFP level was elevated, the assay was repeated and an ultrasound examination performed. Amniocentesis was offered to 67 women with unexplained persistently elevated levels. The outcome of pregnancy was known in 7473 patients (91.8%). Seven of nine known open fetal neural tube defects were detected. All were confirmed, and no unaffected fetuses were aborted on the basis of the screening results. The rates of perinatal death (6.7%), intrauterine growth retardation (11.7%) and prematurity (23.3%) were significantly higher among the patients with unexplained elevated MSAFP levels than among those with normal levels (p less than 0.001). Of 20 patients with unexplained low levels, 10 subsequently had spontaneous abortions and 10 gave birth to term appropriate-for-gestational-age infants. Seven of nine patients who gave birth to infants with autosomal trisomy had MSAFP values below the median. The findings indicate that MSAFP screening is feasible, accurate and acceptable in a low-risk area.     

Faculty development practices in Canadian medical schools.

Twelve Canadian medical schools that had an organized faculty development program were surveyed to evaluate the extent to which such programs were used and to estimate their effectiveness. Common practices included sabbaticals and programs designed to improve instructional skills. The main problems included underfunding, poor participation and inadequate instructor evaluation.     

Sex-related differences in the nuclear population of postpubertal rat pineal gland. A quantitative study.

Male and female parenchymal pineal cell types have been studied throughout postpubertal development to determine the existence of sex-related differences on a time basis. Six age groups (2, 3, 4, 8, 15 and 24 months) of eight rats (4 males and 4 females) were used in this study. Nuclei of both parenchymal pineal cell types were counted in 5 areas of 26.377 microns 2 per pineal gland on semithin sections. Nonparametric statistics of our results (Mann-Whitney U-test and Kruskal-Wallis H-test) demonstrated significant differences between male and female pinealocytes through the stages studied. In all age groups, the number of nuclei per unit area was larger in female rats. Pineoglial cells did not show significant sex-related differences.     

Regional differences among the Finns: a Y-chromosomal perspective

Twenty-two Y-chromosomal markers, consisting of fourteen biallelic markers (YAP/DYS287, M170, M253, P37, M223, 12f2, M9, P43, Tat, 92R7, P36, SRY-1532, M17, P25) and eight STRs (DYS19, DYS385a/b, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393), were analyzed in 536 unrelated Finnish males from eastern and western subpopulations of Finland. The aim of the study was to analyze regional differences in genetic variation within the country, and to analyze the population history of the Finns. Our results gave further support to the existence of a sharp genetic border between eastern and western Finns so far observed exclusively in Y-chromosomal variation. Both biallelic haplogroup and STR haplotype networks showed bifurcated structures, and similar clustering was evident in haplogroup and haplotype frequencies and genetic distances. These results suggest that the western and eastern parts of the country have been subject to partly different population histories, which is also supported by earlier archaeological, historical and genetic data. It seems probable that early migrations from Finno-Ugric sources affected the whole country, whereas subsequent migrations from Scandinavia had an impact mainly on the western parts of the country. The contacts between Finland and neighboring Finno-Ugric, Scandinavian and Baltic regions are evident. However, there is no support for recent migrations from Siberia and Central Europe. Our results emphasize the importance of incorporating Y-chromosomal data to reveal the population substructure which is often left undetected in mitochondrial DNA variation. Early assumptions of the homogeneity of the isolated Finnish population have now proven to be false, which may also have implications for future association studies.