Anamaria Savu

Incidence of heart failure and mortality after acute coronary syndromes

BACKGROUND The long-term incidence of heart failure (HF) in ST-elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI), or unstable angina (UA) patients is uncertain. We examined the 1-year incidence of HF and its association with mortality among patients surviving their first acute coronary syndrome (ACS) hospitalization. METHODS AND RESULTS A retrospective cohort study of patients, aged ≥20 years, with no prior HF, hospitalized for the first time with ACS between April 1, 2002, and December 31, 2008, in Alberta, Canada, and followed up for 1 year. Index HF was defined as HF that developed as a complication during the index ACS hospitalization, and post-discharge HF, as HF developing after discharge from the index ACS hospitalization. Among 9,406 STEMI, 11,008 NSTEMI, and 4,910 UA patients, 13.6%, 14.8%, and 5.2% had index HF, respectively (P < .01). At 1-year, cumulative HF rates were 23.4% in STEMI, 25.4% in NSTEMI, and 16% in UA patients. Among hospital survivors, 1-year mortality rate was 13.9% in patients with index HF, 10.6% in patients with postdischarge HF, and 2.4% in patients with no HF. In multivariable analysis, both index HF (adjusted hazard ratio 3.2, 95% CI 2.7-3.7) and postdischarge HF (adjusted hazard ratio 4.6, 95% CI 3.9-5.4) were associated with 1-year mortality. CONCLUSIONS There are significant differences in the incidence of HF among STEMI, NSTEMI, and UA patients. The increased mortality risk associated with index HF and postdischarge HF suggests a need for vigilant follow-up of all ACS patients for prompt detection and treatment of HF.

Impact of gestational diabetes mellitus and high maternal weight on the development of diabetes, hypertension and cardiovascular disease: a population-level analysis

To examine the association between gestational diabetes mellitus (GDM) and high maternal weight and the risk of development of chronic disease.

Correlation of cardiovascular magnetic resonance imaging findings and endomyocardial biopsy results in patients undergoing screening for heart transplant rejection.

BACKGROUND Endomyocardial biopsy (EMB) is the current gold standard to screen for heart transplant rejection but has important risks and limitations. Cardiovascular magnetic resonance imaging (CMRI) is increasingly used to characterize cardiac function and myocardial tissue. We evaluated the diagnostic accuracy of CMRI compared with EMB and clinically diagnosed heart transplant rejection. METHODS Comprehensive CMRI scans were performed on adult heart transplant recipients within 24 hours of EMB (routine or clinically indicated), before initiation of any anti-rejection therapy, and blinded to EMB results. Multivariable analysis was used to create CMRI diagnostic criteria for comparison with a positive EMB (Grade ≥ 2R or antibody-mediated rejection) and clinical rejection (change in medical therapy to treat rejection). RESULTS Sixty participants (75% male; mean age, 51 ± 14 years) were recruited, providing 73 comparisons between CMRI and EMB for the diagnosis of rejection. Multivariable logistic regression identified myocardial edema (T2 relaxation time) and right ventricular end-diastolic volume index as independent predictors of a positive EMB. Combining threshold right ventricular end-diastolic volume index and edema values predicted a positive EMB with very good accuracy: sensitivity, 93%; specificity, 78%; positive predictive value, 52%; and negative predictive valve, 98%. CMRI was more sensitive than EMB at predicting clinical rejection (sensitivity of 67% vs 58%). CONCLUSIONS CMRI has high sensitivity and high negative predictive value in predicting biopsy-positive heart transplant rejection and may be useful as a screening test before routine EMB. CMRI also has better sensitivity for clinically diagnosed heart transplant rejection and could be helpful in cases of negative rejection on the biopsy specimen.

Risks of gestational diabetes and preeclampsia over the last decade in a cohort of Alberta women.

OBJECTIVES The incidence of gestational diabetes mellitus (GDM) is increasing. However, less is known about the incidence of preeclampsia (PE) and whether it is affected by the presence of GDM. We sought to document the population-level incidence of GDM and PE during the last decade and examine the association between GDM and PE after accounting for established risk factors. METHODS We selected a population-based cohort retrospectively using data from the Alberta Perinatal Health Program registry. Logistic regression was used to examine the association between GDM and PE after adjusting for baseline characteristics. RESULTS Of 426 296 deliveries between 2000 and 2009, 422 672 were in women without pre-existing diabetes. Among these women, the incidence of GDM increased from 3.1% in 2000 to 4.6% in 2009 (P < 0.01), while the incidence of PE remained stable at approximately 1.3% per year. The incidence of PE was significantly higher in women with GDM than in those without GDM (2.6% vs. 1.2%; P < 0.01). After adjustment, women with GDM had a 90% higher risk of PE than those without GDM (OR 1.9; 95% CI 1.7 to 2.1). Other significant risk factors for PE were age, obesity, nulliparity, multifetal gestation, pre-existing hypertension, and chronic kidney disease. CONCLUSION In this contemporary population-based study spanning 10 years, there was a significant increase in the incidence of GDM over time. The higher incidence of PE in women with GDM than in normoglycemic women suggests a need for heightened surveillance and monitoring of women with GDM for the development of PE.

Estimation of relative risk and prevalence ratio

Relative risks (RRs) and prevalence ratios (PRs) are measures of association that are more intuitively interpretable than odds ratios (ORs). Many health science studies report OR estimates, however, even when their designs permit and study questions target RRs and/or PRs. This is, partially, attributable to the popularity and technical advantage (i.e. no restriction on the parameter space) of logistic regression for estimating ORs. To improve this practice, several biostatistical approaches for estimating RR/PR, adjusting for potential confounders, have been proposed. In this paper, we consider two RR/PR estimating methods: (1) the modification of log-binomial regression with the COPY method; and (2) an inverse-probability-of-treatment-weighted (IPTW) log-binomial regression we newly propose. For the COPY method, we rigorously establish the existence and uniqueness of the maximum-likelihood estimator, provided certain degeneracies in the data do not occur. Moreover, the global maximum of the COPY-modified likelihood is shown to occur at an interior point of the restricted parameter space. This result explains why the COPY method avoids convergence problems of log-binomial models frequently. For the IPTW estimator, we show that its simple procedure results in standardized estimates of RR/PR, and discuss its potential challenges, extensions, and an improvement through propensity-score-based grouping of observations. Furthermore, we compare the performances of four RR/PR estimation methods, including the COPY method and IPTW log-binomial regression, on simulated data. We demonstrate a lack of robustness of the COPY method against misspecification of the true relationship between binary outcome and explanatory variables, and show robustness of the IPTW approach in this regard.

Prevalence and Timing of Screening and Diagnostic Testing for Gestational Diabetes Mellitus: A Population-Based Study in Alberta, Canada

OBJECTIVE The extent to which pregnant women are screened for gestational diabetes mellitus (GDM) at the population level is not known. We examined the rate, type, and timing of GDM screening and diagnostic testing in the province of Alberta, Canada. Geographic and temporal differences in screening rates, and maternal risk factors associated with lower likelihood of screening, were also determined. RESEARCH DESIGN AND METHODS Our retrospective linked-database cohort study included 86,842 primiparous women with deliveries between 1 October 2008 and 31 December 2012. Multivariable logistic regression analysis was used to examine maternal factors associated with lower likelihood of GDM screening. RESULTS Overall, 94% (n = 81,304) of women underwent some form of glycemic assessment in the 270 days prior to delivery. The majority (91%) received a 50-g glucose screen (GDS). Women not screened were younger and more likely to smoke and had lower maternal weight and median household income. When a diagnostic 75-g oral glucose tolerance test (OGTT) was indicated, it occurred a median of 10 (interquartile range 7, 15) days after the screen. CONCLUSIONS GDS occurred widely in a system where it was universally recommended and paid for publicly. When indicated, a 75-g OGTT was completed within 15 days in 75% of cases. Our finding that this two-step approach was widely implemented in a timely fashion supports continued endorsement of a two-step approach to screening and diagnosis of GDM. Further research is merited to assess whether the one-step GDM diagnostic approach results in different rates and timing of the 75-g OGTT and affects pregnancy outcomes.

Breast cancer and microbial cancer incidence in female populations around the world : A surprising hyperbolic association

Current literature on cancer epidemiology typically discusses etiology of cancer by cancer type. Risks of different cancer types are, however, correlated at population level and may provide etiological clues. We showed previously an unexpected very high positive correlation between breast cancer (BC) and young‐adult Hodgkin disease incidence rates. In a population‐based case–control study of BC, older ages at the first Epstein–Barr virus exposure, indicated by older ages at onset of infectious mononucleosis, were associated with elevated BC risk. Here we examine BC risk in association with microbial cancer (MC) risk in female populations across the world. MC cancers are cervical, liver and stomach cancers with established causal associations with human papillomaviruses, hepatitis viruses, and helicobacter pylori, respectively. We examined age‐adjusted BC and MC incidence rates in 74 female populations around the world with cancer registries. Our analysis suggests that BC and MC rates are inversely associated in a special mathematical form such that the product of BC rate and MC rate is approximately constant across world female populations. A differential equation model with solutions consistent to the observed inverse association was derived. BC and MC rates were modeled as functions of an exposure level to unspecified common factors that influence the 2 rates. In conjunction with previously reported evidence, we submit a hypothesis that BC etiology may have an appreciable link with microbial exposures (and/or immunological responses to them), the lack of which, especially in early life, may elevate BC risk.

Validation of administrative data case definitions for gestational diabetes mellitus

To examine, using administrative data, the validity of two algorithms for identifying gestational diabetes mellitus: 1) the current National Diabetes Surveillance System algorithm for excluding gestational diabetes cases and 2) gestational diabetes‐specific ICD codes in the delivery‐related hospitalization.

Health Service Use and Costs Associated with Low Birth Weight—A Population Level Analysis

OBJECTIVES To examine differences in health services utilization (HSU) costs in the first year of life between low birth weight (LBW) and normal birth weight (NBW) infants, identify maternal and child characteristics associated with HSU costs, and estimate annual HSU cost of LBW infants for the province of Alberta, Canada. STUDY DESIGN A retrospective cohort study including all live births between 2004 and 2010. Data from the Alberta Perinatal Health Program database were linked to health care administrative data including inpatient, outpatient, and practitioner claims to identify HSU within the first year of life. RESULTS One-year HSU costs among LBW infants (n = 16,209) were

Impact of Colon Cancer Screening on Family History Phenotype

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