Lifestyle variables and the risk of myocardial infarction in the general practice research database

A Cohort Study on Influenza Vaccine and All-Cause Mortality in Older Adults: Methodological Concerns and Public Health Implications

Introduction

In 2020, the restrictions adopted to control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic led to an unprecedented reduction in influenza-related burden. As such, the reduced chance to characterize the circulating virus strains might have increased the risk of vaccine mismatch for the forthcoming winter seasons. The role of an effective influenza vaccination campaign might therefore assume even more value, especially for frail and multimorbid older individuals. Methodological concerns on confounding by indication are always debated in vaccine effectiveness studies and it might be instrumental to give a pragmatic message on an individual’s responsibility to receive the influenza vaccine. We therefore investigated the role of specific confounders to explain the association between influenza vaccine and mortality among older adults.

Methods

Using a primary care database, we formed a cohort of patients aged 65 years or older who were actively registered with their general practitioner (GP) at the beginning of each of nine influenza seasons through to the 2018/2019 season. The study index date was the related seasons’ starting date. Exposure to the influenza vaccine was operationally defined in the 2 months preceding the index date up to 2 weeks before the exit date. Cox regression models were estimated to calculate hazard ratios (HRs) and their 95% confidence intervals (CI) of death between vaccinated and unvaccinated patients in a time-dependent fashion. The potential confounders sequentially entered the model based on their increasing effect size observed in univariate analyses.

Results

Over the 10 years under study, the influenza vaccine showed a significant protective effect in terms of mortality, reaching 13% reduction (HR 0.87, 95% CI 0.80–0.95) in the 2018/2019 influenza season. When we estimated the multivariate model by sequentially adding the potential confounders, there was an inversion of HR (below the unit) that was significantly explained by the covariates coding for a prior history of lower respiratory tract infections and the presence of the pneumococcal vaccine.

Conclusion

In the current pandemic scenario, we cannot divert attention to proper use of face masks, social distancing, and hand hygiene, which are important measures to prevent influenza and other respiratory viral infections. Nonetheless, their effectiveness might be negligible without acceptable coverage for influenza vaccine, especially in older patients with a history of lower respiratory tract infections, which appears to be the main source of confounding by indication.

Ethnic differences in the progression of chronic kidney disease and risk of death in a UK diabetic population: an observational cohort study

OBJECTIVE

To determine ethnic differences in the progression of chronic kidney disease (CKD) and risk of end-stage renal failure (ESRF) and death in adults with type 2 diabetes mellitus (T2DM), and to identify predictors of rapid renal decline.

DESIGN

Observational community-based cohort study undertaken from 2006 to 2016 with nested case-control study.

SETTING

135 inner London primary care practices contributing to the east London Database.

PARTICIPANTS

General practice-registered adults aged 25-85 years with established T2DM and CKD at baseline.

OUTCOMES

The annual rate of renal decline was compared between white, south Asian and black groups, and stratified by proteinuria and raised blood pressure (BP) at baseline. Predictors of rapid renal decline were identified in a nested case-control study. Cox proportional hazards regression was used to determine ethnic differences in the risk of ESRF and death.

RESULTS

Age-sex adjusted annual decline was greatest in the Bangladeshi population. There was stepwise increase in the rate of decline when stratifying the cohort by baseline proteinuria and BP control, with south Asian groups being most sensitive to the combined effect of proteinuria and raised BP after accounting for key confounders.The odds of rapid renal decline were increased for individuals of Bangladeshi, African and Caribbean ethnicity, those with hypertension, proteinuria, cardiovascular disease and with increasing duration of diabetes. Rapid progression was more frequent in younger age groups. Risk of developing ESRF was highest in the black group compared with the white group (HR 1.88, 95% CI 1.11 to 3.19). Risk of death from any cause was 29% lower in the south Asian group compared with the white group (HR 0.71, 95% CI 0.56 to 0.91).

CONCLUSIONS

Proteinuria and hypertension trigger accelerated estimated glomerular filtration rate decline differentially by ethnicity. Active monitoring of younger adults, who have greater odds of rapid progression and the most to gain from interventions, is essential.

Hospital and clinical care costs associated with atrial fibrillation for Medicare beneficiaries in the Cardiovascular Health Study and the Framingham Heart Study

Background

Atrial fibrillation is increasingly prevalent as the US population ages and is associated with significant morbidity and mortality. Care for patients with atrial fibrillation can be costly, US health care costs are comparatively high, and there are few cost estimates available that incorporate detailed measurement of comorbidities and their effects on costs.

Methods and Results

In the Cardiovascular Health Study and the Framingham Heart Study, participants aged 65 years or older with newly diagnosed atrial fibrillation were matched on age and follow-up time to referents free of atrial fibrillation. The total clinical and hospital medical costs paid by Medicare Parts A and B (drug costs from Medicare Part D costs were not included) in the year prior to diagnosis (or matching) were compared with costs in the following year. Estimates were adjusted for other medical conditions and adjusted to 2009 dollars. In the Cardiovascular Health Study, 513 participants were diagnosed with new-onset atrial fibrillation and survived 30 days post-atrial fibrillation diagnosis, and 513 referents (as a control cohort) were identified, with a mean age of 77 years. In the Framingham Heart Study, we identified 336 participants diagnosed with atrial fibrillation, who survived 30 days post-atrial fibrillation diagnosis and matched these participants to 336 referents. We compared these new-onset atrial fibrillation participants with referents, using a difference in difference design to account for both time trends and differences between the two groups. The adjusted incremental cost for participants with atrial fibrillation, compared with referents, was US$18,060 (95% confidence interval: US$14,965-US$21,155) in the Cardiovascular Health Study and US$20,012 (95% confidence interval: US$15,057-US$24,966) in the Framingham Heart Study. The pooled estimate was US$18,601 (95% confidence interval: US$15,981-US$21,234).

Conclusion

Atrial fibrillation was associated with increased costs in the year after diagnosis in two community-based cohorts, even after careful accounting for age, time period, and systematically measured comorbidities.

Identification of potentially relevant genes for myocardial infarction using RNA sequencing data analysis

Myocardial infarction (MI) is a heart disease with high morbidity and mortality rates, thus it is critical to identify genes that serve roles during its pathogenesis. The objective of the present study was to identify potentially relevant genes during the progression of the disease. Blood samples from patients with MI and normal controls (n=3/group) were obtained, the RNA was extracted and cDNA libraries were established. RNA sequencing (RNA-seq) was performed on a HiSeq 2500 platform and fragments per kilobase of exon per million fragments mapped was utilized to calculate the gene expression value following preprocessing of the RNA-seq data. Electronic validation of several identified differentially expressed genes (DEGs) was performed on a Gene Expression Omnibus (GEO) dataset GSE59867 (390 cases and 46 healthy controls). Functional enrichment and protein-protein interaction network analysis was conducted for DEGs. A total of 977 DEGs, including 817 upregulated and 160 downregulated genes were identified in patients with MI. These DEGs were significantly enriched for ‘positive regulation of the immune system process,’ ‘inflammatory response,’ ‘regulation of I-kappaB-kinase/NF-kappaB signaling’ and ‘TNF signaling pathway’. A protein-protein interaction network of the top 40 DEGs was used to identify high degree genes, including interferon induced protein with tetratricopeptide repeats 3 (IFIT3), MX dynamin like GTPase 1 (MX1), major histocompatibility complex, class II, DQ α1 (HLA-DQA1), RAR related orphan receptor A (RORA), prostaglandin D2 synthase (PTGDS), cysteine rich protein 2 (CRIP2), collagen type VI α 2 chain (COL6A2) and S100 calcium binding protein P (S100P). The results of validation in the GEO dataset were consistent with the sequencing analysis. A total of eight genes, including IFIT3, MX1, HLA-DQA1, RORA, PTGDS, CRIP2, COL6A2 and S100P may therefore be considered as potentially relevant genes in the pathology of MI.

Development of an algorithm for determining smoking status and behaviour over the life course from UK electronic primary care records

Background

Patients’ smoking status is routinely collected by General Practitioners (GP) in UK primary health care. There is an abundance of Read codes pertaining to smoking, including those relating to smoking cessation therapy, prescription, and administration codes, in addition to the more regularly employed smoking status codes. Large databases of primary care data are increasingly used for epidemiological analysis; smoking status is an important covariate in many such analyses. However, the variable definition is rarely documented in the literature.

Methods

The Secure Anonymised Information Linkage (SAIL) databank is a repository for a national collection of person-based anonymised health and socio-economic administrative data in Wales, UK. An exploration of GP smoking status data from the SAIL databank was carried out to explore the range of codes available and how they could be used in the identification of different categories of smokers, ex-smokers and never smokers. An algorithm was developed which addresses inconsistencies and changes in smoking status recording across the life course and compared with recorded smoking status as recorded in the Welsh Health Survey (WHS), 2013 and 2014 at individual level. However, the WHS could not be regarded as a “gold standard” for validation.

Results

There were 6836 individuals in the linked dataset. Missing data were more common in GP records (6%) than in WHS (1.1%). Our algorithm assigns ex-smoker status to 34% of never-smokers, and detects 30% more smokers than are declared in the WHS data. When distinguishing between current smokers and non-smokers, the similarity between the WHS and GP data using the nearest date of comparison was κ = 0.78. When temporal conflicts had been accounted for, the similarity was κ = 0.64, showing the importance of addressing conflicts.

Conclusions

We present an algorithm for the identification of a patient’s smoking status using GP self-reported data. We have included sufficient details to allow others to replicate this work, thus increasing the standards of documentation within this research area and assessment of smoking status in routine data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-016-0400-6) contains supplementary material, which is available to authorized users.

In sickness and in health: A cross-sectional analysis of concordance for musculoskeletal pain in 13,507 couples

Background

Musculoskeletal pain conditions are common and create substantial burden for the individual and society. While research has shown concordance between couples for risk of some diseases, e.g. heart disease or diabetes, little information is available on such effects for musculoskeletal pain conditions. Our aims were to investigate the presence of concordance between couples for consultations about pain, and to examine theoretical influences on such concordance.

Methods

This was a 1‐year cross‐sectional study of musculoskeletal pain consultations in a UK primary care database. In total 27,014 patients (13,507 couples) aged between 30 and 74 years were included. The main outcome measure was the presence of a musculoskeletal morbidity read code indicating a consultation for musculoskeletal conditions (any, back, neck, knee, shoulder, foot, osteoarthritis). Logistic regression was used to test associations with odds ratios (OR) and 95% confidence intervals (95% CI).

Results

Patients whose partner had a musculoskeletal pain consultation were also more likely to consult for a musculoskeletal condition (OR 1.22, 95% CI 1.12–1.32). This association was found to be strongest for shoulder disorders (OR 1.91, 95% CI 1.06–3.47). No significant associations were found for other pain conditions.

Conclusion

Results show that partner concordance is present for consultations for some musculoskeletal conditions but not others. Possible explanations for concordance include the shared health behaviours between couples leading to potential heightened awareness of symptoms. Given the high prevalence of musculoskeletal pain within populations, it may be worth considering further the mechanisms that explain partner concordance.

Can analyses of electronic patient records be independently and externally validated? Study 2--the effect of β-adrenoceptor blocker therapy on cancer survival: a retrospective cohort study

OBJECTIVES

To conduct a fully independent, external validation of a research study based on one electronic health record database using a different database sampling from the same population.

DESIGN

Retrospective cohort analysis of β-blocker therapy and all-cause mortality in patients with cancer.

SETTING

Two UK national primary care databases (PCDs): the Clinical Practice Research Datalink (CPRD) and Doctors' Independent Network (DIN).

PARTICIPANTS

CPRD data for 11,302 patients with cancer compared with published results from DIN for 3462 patients; study period January 1997 to December 2006.

PRIMARY AND SECONDARY OUTCOME MEASURES

All-cause mortality: overall; by treatment subgroup (β-blockers only, β-blockers plus other blood pressure lowering medicines (BPLM), other BPLMs only); and by cancer site.

RESULTS

Using CPRD, β-blocker use was not associated with mortality (HR=1.03, 95% CI 0.93 to 1.14, vs patients prescribed other BPLMs only), but DIN β-blocker users had significantly higher mortality (HR=1.18, 95% CI 1.04 to 1.33). However, these HRs were not statistically different (p=0.063), but did differ for patients on β-blockers alone (CPRD=0.94, 95% CI 0.82 to 1.07; DIN=1.37, 95% CI 1.16 to 1.61; p<0.001). Results for individual cancer sites differed by study, but only significantly for prostate and pancreas cancers. Results were robust under sensitivity analyses, but we could not be certain that mortality was identically defined in both databases.

CONCLUSIONS

We found a complex pattern of similarities and differences between databases. Overall treatment effect estimates were not statistically different, adding to a growing body of evidence that different UK PCDs produce comparable effect estimates. However, individually the two studies lead to different conclusions regarding the safety of β-blockers and some subgroup effects differed significantly. Single studies using even internally well-validated databases do not guarantee generalisable results, especially for subgroups, and confirmatory studies using at least one other independent data source are strongly recommended.

Family history of cardiovascular disease, perceived cardiovascular disease risk, and health-related behavior: a review of the literature

BACKGROUND

More than 82 million Americans have 1 or more forms of cardiovascular disease (CVD), accounting for 32.8% of all deaths in the United States. Although the evidence for the familial aggregation of CVD is strong, the relationship between family history (FH) of CVD, perceived risk for CVD, and health-related behavior is poorly understood.

OBJECTIVE

The objective of this article was to review and summarize the published research on the relationship between an FH of CVD, an individual's perceived risk, and health-related behavior to make recommendations for clinical practice and future research.

METHODS

A literature search was conducted using PubMed, CINAHL Plus, and PsycINFO to identify articles that examined the relationship between an FH of CVD, perceived CVD risk, and health-promoting behaviors. A total of 263 unique articles were reviewed. A total of 238 were excluded, resulting in a total of 25 articles included in the review.

RESULTS

There was a positive relationship between a reported FH of CVD and perceived risk. However, the relationship between an FH of CVD and health-related behavior change and perceived risk and behavior change was inconsistent.

CONCLUSIONS

A person's awareness of his or her FH of CVD or his or her own risk for CVD is not a sufficient predictor of changes in his or her health-related behavior. Future studies are needed to better explain the processes by which perceived CVD risk or FH of CVD can be used to affect health-related behavior changes. It appears that both FH and perceived personal risk for CVD are necessary but not sufficient conditions to change health-related behavior in high-risk populations. Future studies should also test interventions that help individuals with an FH of CVD attribute increased personal risk to themselves for developing CVD, while providing lifestyle management options to minimize their risk.

Prediction of cardiovascular risk using Framingham, ASSIGN and QRISK2: how well do they predict individual rather than population risk?

BACKGROUND

The objective of this study was to evaluate the performance of risk scores (Framingham, Assign and QRISK2) in predicting high cardiovascular disease (CVD) risk in individuals rather than populations.

METHODS AND FINDINGS

This study included 1.8 million persons without CVD and prior statin prescribing using the Clinical Practice Research Datalink. This contains electronic medical records of the general population registered with a UK general practice. Individual CVD risks were estimated using competing risk regression models. Individual differences in the 10-year CVD risks as predicted by risk scores and competing risk models were estimated; the population was divided into 20 subgroups based on predicted risk. CVD outcomes occurred in 69,870 persons. In the subgroup with lowest risks, risk predictions by QRISK2 were similar to individual risks predicted using our competing risk model (99.9% of people had differences of less than 2%); in the subgroup with highest risks, risk predictions varied greatly (only 13.3% of people had differences of less than 2%). Larger deviations between QRISK2 and our individual predicted risks occurred with calendar year, different ethnicities, diabetes mellitus and number of records for medical events in the electronic health records in the year before the index date. A QRISK2 estimate of low 10-year CVD risk (<15%) was confirmed by Framingham, ASSIGN and our individual predicted risks in 89.8% while an estimate of high 10-year CVD risk (≥ 20%) was confirmed in only 48.6% of people. The majority of cases occurred in people who had predicted 10-year CVD risk of less than 20%.

CONCLUSIONS

Application of existing CVD risk scores may result in considerable misclassification of high risk status. Current practice to use a constant threshold level for intervention for all patients, together with the use of different scoring methods, may inadvertently create an arbitrary classification of high CVD risk.

Cardiac glycosides and the risk of breast cancer in women with chronic heart failure and supraventricular arrhythmia

The aim of this study is to determine whether the use of cardiac glycosides (CGs), drugs used in the treatment of congestive heart failure (CHF) and supra-ventricular arrhythmia, is associated with an increased risk of breast cancer. A cohort of 53,454 women newly diagnosed with CHF or supra-ventricular arrhythmia between January 1, 1988 and December 31, 2010, followed until December 31, 2012, was identified using the United Kingdom Clinical Practice Research Datalink. A nested case-control analysis was performed, where all incident cases of breast cancer occurring during follow-up were identified and matched with up to 10 controls on age, cohort entry date, and duration of follow-up. Conditional logistic regression models were used to estimate adjusted odds ratios (ORs) with 95 % confidence intervals (CIs) of incident breast cancer associated with the use of CGs, along with measures of cumulative duration of use and dose. All analyses considered a one year lag period prior to the event, necessary for latency considerations and to minimize detection bias. The 898 breast cancer cases diagnosed beyond one year of follow-up were matched to 8,940 controls. Overall, use of CGs was not associated with an increased risk of breast cancer when compared to non-use (OR 1.07, 95 % CI 0.90-1.26). Furthermore, the risk did not vary with cumulative duration of use or cumulative dose. The findings of this large population-based study indicate that the use of CGs is not associated with an increased risk of breast cancer. This should provide reassurance to physicians and patients using these drugs.

Smoker, ex-smoker or non-smoker? The validity of routinely recorded smoking status in UK primary care: a cross-sectional study

OBJECTIVE

To investigate how smoking status is recorded in UK primary care; to evaluate whether appropriate multiple imputation (MI) of smoking status yields results consistent with health surveys.

SETTING

UK primary care and a population survey conducted in the community.

PARTICIPANTS

We identified 354 204 patients aged 16 or over in The Health Improvement Network (THIN) primary care database registered with their general practice 2008-2009 and 15 102 individuals aged 16 or over in the Health Survey for England (HSE).

OUTCOME MEASURES

Age-standardised and age-specific proportions of smokers, ex-smokers and non-smokers in THIN and the HSE before and after MI. Using information on time since quitting in the HSE, we estimated when ex-smokers are typically recorded as non-smokers in primary care records.

RESULTS

In THIN, smoking status was recorded for 84% of patients within 1 year of registration. Of these, 28% were smokers (21% in the HSE). After MI of missing smoking data, the proportion of smokers was 25% (missing at random) and 20% (missing not at random). With increasing age, more were identified as ex-smokers in the HSE than THIN. It appears that those who quit before age 30 were less likely to be recorded as an ex-smoker in primary care than people who quit later.

CONCLUSIONS

Smoking status was relatively well recorded in primary care. Misclassification of ex-smokers as non-smokers is likely to occur in those quitting smoking at an early age and/or a long time ago. Those with no smoking status information are more likely to be ex-smokers or non-smokers than smokers.

Can analyses of electronic patient records be independently and externally validated? The effect of statins on the mortality of patients with ischaemic heart disease: a cohort study with nested case-control analysis

OBJECTIVE

To conduct a fully independent and external validation of a research study based on one electronic health record database, using a different electronic database sampling the same population.

DESIGN

Using the Clinical Practice Research Datalink (CPRD), we replicated a published investigation into the effects of statins in patients with ischaemic heart disease (IHD) by a different research team using QResearch. We replicated the original methods and analysed all-cause mortality using: (1) a cohort analysis and (2) a case-control analysis nested within the full cohort.

SETTING

Electronic health record databases containing longitudinal patient consultation data from large numbers of general practices distributed throughout the UK.

PARTICIPANTS

CPRD data for 34 925 patients with IHD from 224 general practices, compared to previously published results from QResearch for 13 029 patients from 89 general practices. The study period was from January 1996 to December 2003.

RESULTS

We successfully replicated the methods of the original study very closely. In a cohort analysis, risk of death was lower by 55% for patients on statins, compared with 53% for QResearch (adjusted HR 0.45, 95% CI 0.40 to 0.50; vs 0.47, 95% CI 0.41 to 0.53). In case-control analyses, patients on statins had a 31% lower odds of death, compared with 39% for QResearch (adjusted OR 0.69, 95% CI 0.63 to 0.75; vs OR 0.61, 95% CI 0.52 to 0.72). Results were also close for individual statins.

CONCLUSIONS

Database differences in population characteristics and in data definitions, recording, quality and completeness had a minimal impact on key statistical outputs. The results uphold the validity of research using CPRD and QResearch by providing independent evidence that both datasets produce very similar estimates of treatment effect, leading to the same clinical and policy decisions. Together with other non-independent replication studies, there is a nascent body of evidence for wider validity.

Representativeness and optimal use of body mass index (BMI) in the UK Clinical Practice Research Datalink (CPRD)

OBJECTIVES

To assess the completeness and representativeness of body mass index (BMI) data in the Clinical Practice Research Datalink (CPRD), and determine an optimal strategy for their use.

DESIGN

Descriptive study.

SETTING

Electronic healthcare records from primary care.

PARTICIPANTS

A million patient random sample from the UK CPRD primary care database, aged ≥16 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

BMI completeness in CPRD was evaluated by age, sex and calendar period. CPRD-based summary BMI statistics for each calendar year (2003-2010) were age-standardised and sex-standardised and compared with equivalent statistics from the Health Survey for England (HSE).

RESULTS

BMI completeness increased over calendar time from 37% in 1990-1994 to 77% in 2005-2011, was higher among females and increased with age. When BMI at specific time points was assigned based on the most recent record, calendar-year-specific mean BMI statistics underestimated equivalent HSE statistics by 0.75-1.1 kg/m(2). Restriction to those with a recent (≤3 years) BMI resulted in mean BMI estimates closer to HSE (≤0.28 kg/m(2) underestimation), but excluded up to 47% of patients. An alternative strategy of imputing up-to-date BMI based on modelled changes in BMI over time since the last available record also led to mean BMI estimates that were close to HSE (≤0.37 kg/m(2) underestimation).

CONCLUSIONS

Completeness of BMI in CPRD increased over time and varied by age and sex. At a given point in time, a large proportion of the most recent BMIs are unlikely to reflect current BMI; consequent BMI misclassification might be reduced by employing model-based imputation of current BMI.

Completeness and diagnostic validity of recording acute myocardial infarction events in primary care, hospital care, disease registry, and national mortality records: cohort study

OBJECTIVE

To determine the completeness and diagnostic validity of myocardial infarction recording across four national health record sources in primary care, hospital care, a disease registry, and mortality register.

DESIGN

Cohort study.

PARTICIPANTS

21 482 patients with acute myocardial infarction in England between January 2003 and March 2009, identified in four prospectively collected, linked electronic health record sources: Clinical Practice Research Datalink (primary care data), Hospital Episode Statistics (hospital admissions), the disease registry MINAP (Myocardial Ischaemia National Audit Project), and the Office for National Statistics mortality register (cause specific mortality data).

SETTING

One country (England) with one health system (the National Health Service).

MAIN OUTCOME MEASURES

Recording of acute myocardial infarction, incidence, all cause mortality within one year of acute myocardial infarction, and diagnostic validity of acute myocardial infarction compared with electrocardiographic and troponin findings in the disease registry (gold standard).

RESULTS

Risk factors and non-cardiovascular coexisting conditions were similar across patients identified in primary care, hospital admission, and registry sources. Immediate all cause mortality was highest among patients with acute myocardial infarction recorded in primary care, which (unlike hospital admission and disease registry sources) included patients who did not reach hospital, but at one year mortality rates in cohorts from each source were similar. 5561 (31.0%) patients with non-fatal acute myocardial infarction were recorded in all three sources and 11 482 (63.9%) in at least two sources. The crude incidence of acute myocardial infarction was underestimated by 25-50% using one source compared with using all three sources. Compared with acute myocardial infarction defined in the disease registry, the positive predictive value of acute myocardial infarction recorded in primary care was 92.2% (95% confidence interval 91.6% to 92.8%) and in hospital admissions was 91.5% (90.8% to 92.1%).

CONCLUSION

Each data source missed a substantial proportion (25-50%) of myocardial infarction events. Failure to use linked electronic health records from primary care, hospital care, disease registry, and death certificates may lead to biased estimates of the incidence and outcome of myocardial infarction.

TRIAL REGISTRATION

NCT01569139 clinicaltrials.gov.

Sex differences in young patients with acute myocardial infarction

AIMS

To identify sex differences in risk factors, presenting symptoms and outcomes of young patients with acute myocardial infarction.

METHODS

We adopted a comprehensive approach and performed two parallel studies: (1) using provincial administrative databases from Quebec, Canada from 2000 to 2007, we identified baseline characteristics and post-acute myocardial infarction survival of patients aged < 50 years (n = 10,619); (2) to overcome the lack of clinical data in the administrative databases, a medical chart review was performed on 215 patients < 50 years of age with an acute myocardial infarction between April 2000 and August 2006 from our institution.

RESULTS

Administrative cohort: fewer women than men sought medical attention for retrosternal chest pain 1-month pre-acute myocardial infarction (P = 0.035). Diabetes and hypertension were more prevalent in women, and patients equally received interventional procedures post-infarction. Diabetes significantly reduced post-infarction survival in men and women [HR = 2.02 (95% CI 1.21-3.36) and HR = 2.25 (95% CI 1.06-4.80), respectively]. However, young women had greater post-infarction mortality in-hospital and up to 1 year after discharge (4.23% vs. 2.21%, respectively; P = 0.005). Medical chart review: diabetes and hypertension were more prevalent in women, while men were more obese. There were no significant sex differences in typical presenting symptoms, or in interventional procedures post-infarction.

CONCLUSIONS

Young men and women with acute myocardial infarctions equally presented with retrosternal chest pain, although fewer women sought medical attention for retrosternal chest pain before admission. Diabetes and hypertension were more prevalent in young women, and mortality was higher in young female patients. Our results highlight the continued need for diabetes prevention and control in young patients, especially women.

Low-density lipoprotein cholesterol, apolipoprotein B, and risk of coronary heart disease: from familial hyperlipidemia to genomics

Coronary heart disease (CHD) affects 17 million people in the United States and accounts for over a million hospital stays each year. Technological advances, especially in genetics and genomics, have changed our understanding of the risk factors for developing CHD. The purpose of this article is to review low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apo B), and risk of CHD. The article focuses on five topics: (1) a description of lipoprotein classes, normal lipoprotein metabolism, and the biological mechanism of atherosclerosis; (2) a review of selected epidemiologic and clinical trial studies examining the associations between elevated LDL-C and apo B with CHD; (3) a brief review of the familial forms of hyperlipidemia; (4) a description of variants in genes that have been associated with higher LDL-C levels in candidate gene studies and genome-wide association studies (GWAS); and (5) nursing implications, including a discussion on how genetic tests are evaluated and the current clinical utility and validity of genetic tests for CHD.

Mental ill-health across the continuum of body mass index

BACKGROUND

Several studies have found a non-linear relationship between mental ill-health and BMI with higher rates in both the underweight and the obese. This study evaluated the shape of the relationship between BMI and distress, suicidal ideation and self-reported mental ill-health conditions in a large population sample.

METHODS

Data were drawn from the South Australian Monitoring and Surveillance System (SAMSS) for the years 2002 to 2009 (n = 46,704). SAMSS monitors population trends in state and national risk factors and chronic diseases. Samples are drawn from all households with a functioning number in the Australian White Pages. Computer assisted telephone interviews collected information on self-reported height and weight, demographic and health behaviours. Respondents completed the Kessler Distress and suicidal ideation scales and reported specific mental ill-health conditions. BMI was categorized into deciles to allow for assessment of the shape of any associations with other variables. Logistic regression was used to examine associations between each mental ill-health condition and BMI-decile controlling for age in the base model. This was followed by a full model that added SES and the health-adverse coping behaviours of smoking, alcohol and physical activity to test for changes from the base model.

RESULTS

Non-linear associations were observed between BMI-decile and mental ill-health but statistically significantly greater odds of mental ill-health were observed only in the obese and not in the underweight after controlling for age, health-adverse behaviours and socioeconomic status. The association between BMI and mental ill-health might best be described as 'threshold'. Elevated odds were apparent for middle-aged persons, whereas younger and older individuals had a significantly lower odds of having a mental ill-health condition.

CONCLUSIONS

In conclusion, this study has provided no support for the hypothesis of increased mental ill-health problems in the underweight but it has demonstrated the non-linear relationships between BMI and mental ill-health and between BMI and health-adverse behaviours. Non-linear relationships with BMI need to be recognized and addressed during analysis.

Issues in multiple imputation of missing data for large general practice clinical databases

PURPOSE

Missing data are a substantial problem in clinical databases. This paper aims to examine patterns of missing data in a primary care database, compare this to nationally representative datasets and explore the use of multiple imputation (MI) for these data.

METHODS

The patterns and extent of missing health indicators in a UK primary care database (THIN) were quantified using 488 384 patients aged 16 or over in their first year after registration with a GP from 354 General Practices. MI models were developed and the resulting data compared to that from nationally representative datasets (14 142 participants aged 16 or over from the Health Survey for England 2006 (HSE) and 4 252 men from the British Regional Heart Study (BRHS)).

RESULTS

Between 22% (smoking) and 38% (height) of health indicator data were missing in newly registered patients, 2004-2006. Distributions of height, weight and blood pressure were comparable to HSE and BRHS, but alcohol and smoking were not. After MI the percentage of smokers and non-drinkers was higher in THIN than the comparison datasets, while the percentage of ex-smokers and heavy drinkers was lower. Height, weight and blood pressure remained similar to the comparison datasets.

CONCLUSIONS

Given available data, the results are consistent with smoking and alcohol data missing not at random whereas height, weight and blood pressure missing at random. Further research is required on suitable imputation methods for smoking and alcohol in such databases.

Discontinuation of statin therapy following an acute myocardial infarction: a population-based study

AIMS

Randomized clinical trials have shown that statins can reduce mortality after acute myocardial infarction (AMI). However, the impact of changes in patterns of statin use, particularly stopping statins, on survival post-AMI is unknown. Our objective was to estimate the extent to which different patterns of statin use are associated with post-AMI mortality.

METHODS AND RESULTS

Population-based, cohort study, from 2002 through 2004 in the United Kingdom General Practice Research Database (GPRD), involving patients surviving 90 days after their first AMI. Past statin use was defined as any statin prescription within 90 days before AMI; statin use post-AMI as any statin prescription within 90 days after AMI. Cohort entry was at day 90 post-AMI; subjects were followed for 1 year. Four groups were identified: (i) non-users (patients never on statins); (ii) users (on statins before and continued post-AMI); (iii) starters (started statins after the event); and (iv) stoppers (stopped statins after the event). Hazard ratios (HRs) were estimated using Cox proportional hazards model. The main outcome measure was 1-year all-cause mortality. The cohort included 9939 AMI survivors (mean age: 68.4 ± 12.8 years; 60.3% men), 22.7% of whom were not prescribed a statin post-AMI. When the non-user group (n = 2124) was considered as the reference, the adjusted HRs (95% confidence intervals) of death were 0.84 (0.66-1.09) for users (n = 2026), 0.72 (0.57-0.90) for starters (n = 5652), and 1.88 (1.13-3.07) for stoppers (n = 137). Stoppers of control medications (aspirin, β-blockers, and proton pump inhibitors) were not associated with increased mortality.

CONCLUSION

Discontinuation of statins in survivors of a first AMI was relatively rare in this cohort. However, statin discontinuation was associated with higher total mortality and this may represent a biological rebound or/and a risk-treatment mismatch phenomenon, where treatment is withdrawn from very ill patients. While awaiting further research, at present statin use should only be withdrawn under judicious clinical supervision.

Cardiovascular high-risk patients--treat to protect, but whom?

Current guidelines for the prevention of coronary heart disease emphasize the importance of global cardiovascular risk, which requires the evaluation and treatment of multiple risk factors. Cardiovascular risk can be stratified with the Framingham algorithm, which produces a numerical score related to the presence of risk factors, such as hypertension, dyslipidemia, and smoking. However, this algorithm is not generally applicable to European countries, particularly for those countries where the risk for cardiovascular disease is low. The SCORE (Systematic COronary Risk Evaluation) project has produced risk charts that are based on cholesterol, blood pressure, and age for low-risk European countries (Belgium, France, Greece, Italy, Luxembourg, Spain, and Switzerland) and high-risk countries. Assessments of end-organ damage can provide further prognostic information, particularly in intermediate-risk patients, but the value of including additional biomarkers in risk stratification remains to be confirmed. Risk for coronary heart disease is high or very high in more than 50% of hypertensive patients. Risk appears to be underestimated in clinical practice, particularly in those patients at highest risk. Major intervention trials with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have shown that these agents reduce the risk for cardiovascular events in patients at all levels of risk, with the greatest benefits seen in those at highest risk.