Revascularization and cardioprotective drug treatment in myocardial infarction patients: how do they impact on patients' survival when delivered as usual care

BACKGROUND: Randomized clinical trials showed the benefit of pharmacological and revascularization treatments in secondary prevention of myocardial infarction (MI), in selected population with highly controlled interventions. The objective of this study is to measure these treatments' impact on the cardiovascular (CV) mortality rate among patients receiving usual care in the province of Quebec. METHODS: The study population consisted of a "naturalistic" cohort of all patients ≥ 65 years old living in the Quebec province, who survived a MI (ICD-9: 410) in 1998. The studied dependant variable was time to death from a CV disease. Independent variables were revascularization procedure and cardioprotective drugs. Death from a non CV disease was also studied for comparison. Revascularization procedure was defined as percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft (CABG). The exposure to cardioprotective drugs was defined as the number of cardioprotective drug classes (Acetylsalicylic Acid (ASA), Beta-Blockers, Angiotensin-Converting Enzyme (ACE) Inhibitors, Statins) claimed within the index period (first 30 days after the index hospitalization). Age, gender and a comorbidity index were used as covariates. Kaplan-Meier survival curves, Cox proportional hazard models, logistic regressions and regression trees were used. RESULTS: The study population totaled 5596 patients (3206 men; 2390 women). We observed 1128 deaths (20%) within two years following index hospitalization, of them 603 from CV disease. The CV survival rate at two years is much greater for patients with revascularization, regardless of pharmacological treatments. For patients without revascularization, the CV survival rate increases with the number of cardioprotective drug classes claimed. Finally, Cox proportional hazard models, regression tree and logistic regression analyses all revealed that the absence of revascularization and, to a lower extent, absence of cardioprotective drugs were major predictors for CV death, even after adjusting for age, gender and comorbidity. CONCLUSION: Considering usual care management of MI in the province of Quebec in 1998, CV survival is positively correlated to the presence of a revascularization procedure and to the intensity of cardioprotective pharmacological treatment. These results are coherent with data from randomized control trials

Prevalence of claims-based recurrent low back pain in a Canadian population: A secondary analysis of an administrative database

BACKGROUND: There is a vast literature reporting that the point prevalence of low back pain (LBP) is high and increasing. It is also known that a large proportion of acute LBP episodes are recurrent within 12 months. However, few studies report the annual trends in the prevalence of recurrent LBP or describe these trends according to age and sex categories. METHODS: We conducted a retrospective cohort study involving 401 264 adults selected from the administrative database of physician claims for the province of Quebec, Canada. These adults, aged 18 years and over, met the criteria of having consulted a physician three times within a 365-day period between 2000 and 2007 for a LBP condition corresponding to ICD-9 codes 721, 722, 724 or 739. All data were analyzed by sex and clustered according to specific age categories. RESULTS: We observed a decrease from 1.64% to 1.33% in the annual prevalence between 2000 and 2007 for men. This decrease in prevalence was mostly observed between 35 and 59 years of age. Older (≥65 years) women were 1.35 times more at risk to consult a physician for LBP in a recurrent manner than older men. The most frequently reported diagnosis was non-specific LBP between 2000 to 2007. During the same period, sequelae of previous back surgery and spinal stenosis were the categories with the largest increases. CONCLUSION: The annual prevalence of claims-based recurrent LBP progressively decreased between 2000 and 2007 for younger adults (<65 years) while older adults (≥65 years) showed an increase. Given the aging Canadian population, recurrent low back pain could have an increasing impact on the quality of life of the elderly as well as on the healthcare system

Validating metabolic syndrome through principal component analysis in a medically diverse, realistic cohort

Abstract: Background: The concept of metabolic syndrome has been subject to etiological and clinical controversies in recent years. Associations among the five risk factors (obesity, high blood pressure, high blood sugar, high triglyceride levels and low HDL cholesterol) may help establish the validity of the concept and its application, but most such studies have been conducted on targeted cohorts not representative of an actual population. Methods: We used principal component analysis (PCA) to analyze the structure of the physiological components of metabolic syndrome in 7213 patients contained in an administrative database for the CHUS hospital in Sherbrooke, Quebec, a realistic cohort with diverse medical histories. We validated the results by repeating the analysis on stratified and random subgroups of patients, and on different combinations of risk factors. The first axis of the PCA was used to predict coronary heart disease (CHD) and diabetes. Results: The two first axes explained 53% of the variance. The first axis (33%) was associated in the expected direction with all five predictor variables, consistent with its interpretation as metabolic syndrome. All validation analyses strongly confirmed this interpretation. The scores from the first axis were more predictive of subsequent CHD and diabetes than the formal definition of metabolic syndrome. Conclusions: These results suggest that the concept of metabolic syndrome accurately captures an existing underlying physiological process. A continuous indicator could be constructed to identify more accurately metabolic syndrome thus improving risk assessment for CHD and diabetes mellitus. Metabolic syndrome can be measured well even without all five predictors, though measurement is improved by PCA relative to dichotomized definitions. However, discrepancies with other studies suggest that our results may not be generalizable, perhaps because our cohort tends to be sicker

Spatial variation in the management and outcomes of acute coronary syndrome

BACKGROUND: Regional disparities in medical care and outcomes with patients suffering from an acute coronary syndrome (ACS) have been reported and raise the need to a better understanding of links between treatment, care and outcomes. Little is known about the relationship and its spatial variability between invasive cardiac procedure (ICP), hospital death (HD), length of stay (LoS) and early hospital readmission (EHR). The objectives were to describe and compare the regional rates of ICP, HD, EHR, and the average LoS after an ACS in 2000 in the province of Quebec. We also assessed whether there was a relationship between ICP and HD, LoS, and EHR, and if the relationships varied spatially. METHODS: Using secondary data from a provincial hospital register, a population-based retrospective cohort of 24,544 patients hospitalized in Quebec (Canada) for an ACS in 2000 was built. ACS was defined as myocardial infarction (ICD-9: 410) or unstable angina (ICD-9: 411). ICP was defined as the presence of angiography, angioplasty or aortocoronary bypass (CCA: 480–483, 489), HD as all death cause at index hospitalization, LoS as the number of days between admission and discharge from the index hospitalization, and EHR as hospital readmission for a coronary heart disease ≤30 days after discharge from hospital. The EHR was evaluated on survivors at discharge. RESULTS: ICP rate was 43.7% varying from 29.4% to 51.6% according to regions. HD rate was 6.9% (range: 3.3–8.2%), average LoS was 11.5 days (range: 7.5–14.4; median LoS: 8 days) and EHR rate was 8.3% (range: 4.7–14.2%). ICP was positively associated with LoS and negatively with HD and EHR; the relationship between ICP and LoS varied spatially. An increased distance to a specialized cardiology center was associated with a decreased likelihood of ICP, a decrease in LoS, but an increased likelihood of EHR. CONCLUSION: The main results of this study are the regional variability of the outcomes even after accounting for age, gender, ICP and distance to a cardiology center; the significant relationships between ICP and HD, LoS and EHR, and the spatial variability in the relationships between ICP and LoS

Rural-urban disparities in the management and health issues of chronic diseases in Quebec (Canada) in the early 2000s

Abstract: Introduction: The ‘Commission on the Future of Health Care in Canada’ recognized that people living in rural and remote areas of Canada are at a disadvantage in health status, access to care and health professionals, and it considers the fight against these problems as a national priority. Although some attention has been paid to the prevalence of chronic diseases, very few studies have studied specifically the management and health issues in populations with chronic diseases in relation to rurality. The objective of this study was to describe systematic gaps across rural and urban populations in incidence, mortality, morbidity, material and human resources utilization, and drug management for three important chronic diseases: atherosclerosis, osteoporosis and diabetes. Methods: Three retrospective population-based cohort studies were used. Three study populations were selected: an atherosclerotic population including patients newly hospitalized for a myocardial infarction (MI), an osteoporotic population including the at risk population who have suffered from a fragility fracture (FF) and, finally, a diabetic population that includes only incident cases of diabetes patients. For each of the three chronic diseases, variables were selected and classified in six categories: incidence, mortality, morbidity, material resources utilization, physician consultation and drug treatment. The Statistical Area Classification (SAC) was used as the rurality definition and contains six categories including two urban areas − Census Metropolitan Areas (CMA), or metropolitan areas, and Census Agglomeration (CA), or small towns − and four rural areas: Strong, Moderate, Weak and No Metropolitan influenced zones (MIZ), depending on the proportion of the workforce that commutes to urban areas. Each disease-related variable was described using age- and sex-adjusted rates. For comparing rates between rurality classes, the adjusted relative risks were calculated using the CMA as the reference group. The χ2 was used to test for the equality of risks. Results: A common pattern was identified from this study: for all three studied diseases, the material resources utilization rates and the specialist (other than internist) consultation rates were almost always statistically lower in small towns and rural areas when compared with metropolitan areas. Mortality rates and drug utilization rates were very similar among regions, except for hormone replacement therapy in women where utilization rates were higher in small towns and rural areas compared with metropolitan areas. Among observations that were not common to all three chronic diseases, the first is that MI incidence was greater in small towns and in Weak MIZ compared with metropolitan areas, fragility fractures seem to be marginally more frequent in small towns but less frequent in rural areas compared with metropolitan areas, while an increased incidence rate of diabetes is observed in remote region and a smaller risk in moderate MIZ compared with metropolitan areas. For both atherosclerosis and diabetes, morbidity rates were always statistically higher in small towns and in rural areas. This was not the case for patients with osteoporotic fractures where similar morbidity rates across regions were observed, except in strong MI which show the lowest morbidity rate. Conclusions: There was substantially lower utilization of specialized services in non-metropolitan areas for all three diseases (myocardial infarction, osteoporosis, and diabetes). However, this did not translate into consistent differences in mortality and morbidity outcomes. This suggests that the impact of differential care utilization is specific to each disease, with indications that some important services may be under-utilized in rural areas, while others may be over-utilized in urban areas without improvement in outcomes

Association between floods and acute cardiovascular diseases: a population-based cohort study using a geographic information system approach

Abstract: Background: Floods represent a serious threat to human health beyond the immediate risk of drowning. There is few data on the potential link between floods and direct consequences on health such as on cardiovascular health. This study aimed to explore the impact of one of the worst floods in the history of Quebec, Canada on acute cardiovascular diseases (CVD). Methods: A cohort study with a time series design with multiple control groups was built with the adult population identified in the Quebec Integrated Chronic Disease Surveillance System. A geographic information system approach was used to define the study areas. Logistic regressions were performed to compare the occurrence of CVD between groups. Results: The results showed a 25%–27% increase in the odds in the flooded population in spring 2011 when compared with the population in the same area in springs 2010 and 2012. Besides, an increase up to 69% was observed in individuals with a medical history of CVD. Conclusion: Despite interesting results, the association was not statistically significant. A possible explanation to this result can be that the population affected by the flood was probably too small to provide the statistical power to answer the question, and leaves open a substantial possibility for a real and large effect

Optimal strategy to identify incidence of diagnostic of diabetes using administrative data

<p>Abstract</p> <p>Background</p> <p>Accurate estimates of incidence and prevalence of the disease is a vital step toward appropriate interventions for chronic disease like diabetes. A growing body of scientific literature is now available on producing accurate information from administrative data. Advantages of use of administrative data to determine disease incidence include feasibility, accessibility and low cost, but straightforward use of administrative data can produce biased information on incident cases of chronic disease like diabetes. The present study aimed to compare criteria for the selection of diabetes incident cases in a medical administrative database.</p> <p>Methods</p> <p>An exhaustive retrospective cohort of diabetes cases was constructed for 2002 using the Canadian National Diabetes Surveillance System case definition (one hospitalization or two physician claims with a diagnosis of diabetes over a 2-year period) with the Quebec health service database. To identify previous occurrence of diabetes in the database, a five-year observation period was evaluated using retrograde survival function and kappa agreement. The use of NDSS case definition to identify incident cases was compared to a single occurrence of an ICD-9 code 250 in the records using the McNemar test.</p> <p>Results</p> <p>Retrograde survival function showed that the probability of being a true incident case after a 5-year diabetes-free observation period was almost constant and near 0.14. Agreement between 10 years (maximum period) and 5 years and more diabetes-free observation periods were excellent (kappa > 0.9). Respectively 41,261 and 37,473 incident cases were identified using a 5-year diabetes-free observation period with NDSS definition and using a single ICD-9 code 250.</p> <p>Conclusion</p> <p>A 5-year diabetes-free observation period was a conservative time to identify incident cases in an administrative database using one ICD-9 code 250 record.</p

Cardiovascular safety of celecoxib in acute myocardial infarction patients: a nested case-control study

The objective was to measure the impact of exposure to coxibs and non-steroidal antiinflammatory drugs (NSAID) on morbidity and mortality in older patients with acute myocardial infarction (AMI). A nested case-control study was carried out using an exhaustive population-based cohort of patients aged 66 years and older living in Quebec (Canada) who survived a hospitalization for AMI (ICD-9 410) between 1999 and 2002. The main variables were all-cause and cardiovascular (CV) death, subsequent hospital admission for AMI, and a composite end-point including recurrent AMI or CV death. Conditional logistic regressions were used to estimate the risk of mortality and morbidity. A total of 19,823 patients aged 66 years and older survived hospitalization for AMI in the province of Quebec between 1999 and 2002. After controlling for covariables, the risk of subsequent AMI and the risk of composite end-point were increased by the use of rofecoxib. The risk of subsequent AMI was particularly high for new rofecoxib users (HR 2.47, 95% CI 1.57–3.89). No increased risk was observed for celecoxib users. No increased risk of CV death was observed for patients exposed to coxibs or NSAIDs. Patients newly exposed to NSAIDs were at an increased risk of death (HR 2.22, 95% CI 1.30–3.77) and of composite end-point (HR 2.28, 95% CI 1.35–3.84). Users of rofecoxib and NSAIDs, but not celecoxib, were at an increased risk of recurrent AMI and of composite end-point. Surprisingly, no increased risk of CV death was observed. Further studies are needed to better understand these apparently contradictory results

Bone mineral density measurement and osteoporosis treatment after a fragility fracture in older adults: regional variation and determinants of use in Quebec

BACKGROUND: Osteoporosis (OP) is a skeletal disorder characterized by reduced bone strength and predisposition to increased risk of fracture, with consequent increased risk of morbidity and mortality. It is therefore an important public health problem. International and Canadian associations have issued clinical guidelines for the diagnosis and treatment of OP. In this study, we identified potential predictors of bone mineral density (BMD) testing and OP treatment, which include place of residence. METHODS: Our study was a retrospective population-based cohort study using data from the Quebec Health Insurance Board. The studied population consisted of all individuals 65 years and older for whom a physician claimed a consultation for a low velocity vertebral, hip, wrist, or humerus fracture in 1999 and 2000. Individuals were considered to have undergone BMD testing if there was a claim for such a procedure within two years following a fracture. They were considered to have received an OP treatment if there was at least one claim to Quebec's health insurance plan (RAMQ) for OP treatment within one year following a fracture. We performed descriptive analyses and logistic regressions by gender. Predictors included age, site of fracture, social status, comorbidity index, prior BMD testing, prior OP treatment, long-term glucocorticoid use, and physical distance to BMD device. RESULTS: The cohort, 77% of which was female, consisted of 25,852 individuals with fragility fractures. BMD testing and OP treatment rates were low and gender dependent (BMD: men 4.6%; women 13.1%; OP treatment: men 9.9%; women 29.7%). There was an obvious regional variation, particularly in BMD testing, ranging from 0 to 16%. Logistic regressions demonstrate that individuals living in long term care facilities received less BMD testing. Patients who had suffered from vertebral fractures, or who had received prior OP treatment or BMD testing, regardless of gender, subsequently received more BMD testing and OP treatments. Furthermore, increasing the distance between a patient's residence and BMD facility precluded likelihood of BMD testing. CONCLUSION: BMD testing rate was extremely low but not completely explained by reduced physical access; gender, age, social status, prior BMD testing and OP treatment were all important predictors for future BMD testing and OP treatment