Exploring variation in timely reperfusion treatment in ST-segment elevation myocardial infarction in Norway: a national register-based cohort study.

OBJECTIVES: This study aimed to investigate determinants of reperfusion within recommended time limits (timely reperfusion) for ST-segment elevation myocardial infarction patients, exploring the impact of geography, patient characteristics and socio-economy. DESIGN: National register-based cohort study. SETTING: Multilevel logistic regression models were applied to examine the associations between timely reperfusion and residency in hospital referral areas and municipalities, patient characteristics, and socio-economy. PARTICIPANTS: 7607 Norwegian ST-segment elevation myocardial infarction patients registered in the Norwegian Registry of Myocardial Infarction during 2015-2018. MAIN OUTCOME MEASURES: The odds of timely reperfusion by primary percutaneous coronary intervention (PCI) or fibrinolysis. RESULTS: Among 7607 ST-segment elevation myocardial infarction patients in Norway, 56% received timely reperfusion. The Norwegian goal is 85%. While 81% of the patients living in the Oslo hospital referral area received timely reperfusion, only 13% of the patients living in Finnmark did so.Patients aged 75-84 years had lower odds of timely reperfusion than patients below 55 years of age (OR 0.73, 95% CI 0.61 to 0.87). Patients with moderate or high comorbidity had lower odds than patients without (OR 0.81, 95% CI 0.68 to 0.95 and OR 0.61, 95% CI 0.44 to 0.84). More than 2 hours from symptom onset to first medical contact gave lower odds than less than 30 min (OR 0.63, 95% CI 0.54 to 0.72). 1-2 hours of travel time to a PCI centre (OR 0.39, 95% CI 0.31 to 0.49) and more than 2 hours (OR 0.22, 95% CI 0.16 to 0.30) gave substantially lower odds than less than 1 hour of travel time. CONCLUSIONS: The varying proportion of patients receiving timely reperfusion across hospital referral areas implies inequity in fundamental healthcare services, not compatible with established Norwegian health policy. The importance of travel time to PCI centre points at the expanded use of prehospital pharmacoinvasive strategy to obtain the goals of timely reperfusion in Norway.

Lipid Levels During Adult Lifetime in Men and Women With and Without a Subsequent Incident Myocardial Infarction: A Longitudinal Analysis of Data From the Tromsø Study 1974 to 2016.

Background The atherosclerotic effect of an adverse lipid profile is assumed to accumulate throughout life, leading to increased risk of myocardial infarction (MI). Still, little is known about age at onset and duration of unfavorable lipid levels before MI. Methods and Results Longitudinal data on serum lipid levels for 26 130 individuals (50.5% women, aged 20-89 years) were obtained from 7 population-based health surveys in Tromsø, Norway. Diagnoses of MI were obtained from national registers. A linear mixed model was applied to compare age- and sex-specific mean values of total cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglyceride concentration by MI status (MI versus non-MI). Already from young adulthood, 20 to 35 years before the incident MI, individuals with a subsequent incident MI had on average more adverse lipid levels than individuals of the same age and sex without MI. Analogous to a dose-response relationship, there was a clear trend toward more severe adverse lipid levels the lower the age at incident MI (P<0.001, test for trend through ordered categories <55, 55-74, ≥75 years). This trend was particularly pronounced for high-density lipoprotein cholesterol in percentage of total cholesterol (both sexes) and for the relative relationship between triglyceride, high-density lipoprotein cholesterol, and total cholesterol level (women). The difference in mean lipid level by MI status was just as large in women as in men, but the age pattern differed (P≤0.05, tests of 3-way interaction). Conclusions Compared with general population mean levels, adverse lipid levels were seen 20 to 35 years before the incident MI in both men and women.

Treatment and 30-Day Mortality after Myocardial Infarction in Prostate Cancer Patients: A Population-Based Study from Norway.

INTRODUCTION: There is limited knowledge about the use of invasive treatment and mortality after acute myocardial infarction (AMI) in prostate cancer (PCa) patients. We therefore wanted to compare rates of invasive treatment and 30-day mortality between AMIs in patients with PCa and AMIs in the general Norwegian male population. METHODS: Norwegian population-based registry data from 2013 to 2019 were used in this cohort study to identify AMIs in patients with a preceding PCa diagnosis. We compared invasive treatment rates and 30-day mortality in AMI patients with PCa to the same outcomes in all male AMI patients in Norway. Invasive treatment was defined as performed angiography with or without percutaneous coronary intervention or coronary artery bypass graft surgery. Standardized mortality (SMR) and incidence ratios, and logistic regression were used to evaluate the association between PCa risk groups and invasive treatment. RESULTS: In 1,018 patients with PCa of all risk groups, the total rates of invasive treatment for AMIs were similar to the rates in the general AMI population. In patients with ST-segment elevation AMIs, rates were lower in metastatic PCa compared to localized PCa (OR 0.15, 95% CI: 0.04-0.49). For non-ST-segment elevation AMIs, there were no differences between PCa risk groups. The 30-day mortality after AMI was lower in PCa patients than in the total population of similarly aged AMI patients (SMR 0.77, 95% CI: 0.61-0.97). CONCLUSION: Except for patients with metastatic PCa experiencing an ST-segment elevation AMI, PCa patients were treated as frequent with invasive treatment for their AMI as the general AMI population. 30-day all-cause mortality was lower after AMI in PCa patients compared to the general AMI population.

Drug-Eluting versus Bare-Metal Stents in Saphenous Vein Grafts Compared to Native Coronary Vessels: The Norwegian Coronary Stent Trial Study.

BACKGROUND: Drug-eluting stents (DES) reduce target lesion revascularization (TLR) with no effect on mortality or myocardial infarction (MI) compared to bare-metal stents (BMS) in native vessels. Randomized stent studies in saphenous vein grafts (SVG) are few and the reported effects are ambiguous. The Norwegian Coronary Stent Trial study is the first to randomize lesions to percutaneous coronary intervention in native vessels and SVG. AIMS: The aim of this study was to compare the rate of mortality, MI, and TLR across stent and vessel types. METHODS: In this substudy, 6,087 patients with a single lesion in native vessels and 164 in SVG were followed for 5 years. RESULTS: MI was more frequent in SVG (subdistributional hazard ratio [SHR] 4.95 (3.75-6.54, p < 0.001), but not affected by stent type. In the first 500 days, DES reduced TLR in native vessels (SHR 0.21 (0.15-0.30) p < 0.001) and SVG (SHR 0.18 (0.04-0.80) p = 0.02). Thereafter, DES and BMS were equivalent in native vessels, but DES had a higher TLR rate than BMS in SVG (SHR 3.31 (1.23-8.94) p = 0.02). After 5 years, the TLR rate was still significantly lower for DES in native vessels (3.2% vs. 7.8%, p < 0.001) but not in SVG (21.4% vs. 18. 4%). CONCLUSION: In SVG, no difference in TLR between DES and BMS was observed after 5 years in contrast to persistent benefit in native vessels. The high rate of TLR and MI in SVG makes treatment of native vessels a preference whenever feasible and better treatment options for SVG are warranted.

Validating Acute Myocardial Infarction Diagnoses in National Health Registers for Use as Endpoint in Research: The Tromsø Study.

PURPOSE: To assess whether acute myocardial infarction (MI) diagnoses in national health registers are sufficiently correct and complete to replace manual collection of endpoint data for a population-based, epidemiological study. PATIENTS AND METHODS: Using the Tromsø Study Cardiovascular Disease Register for 2013-2014 as gold standard, we calculated correctness (defined as positive predictive value (PPV)) and completeness (defined as sensitivity) of MI cases in the Norwegian Myocardial Infarction Register and the Norwegian Patient Register separately and in combination. We calculated the sensitivity and PPV with 95% confidence intervals using the Clopper-Pearson Exact test. RESULTS: We identified 153 MI cases in the gold standard. In the Norwegian Myocardial Infarction Register, we found a PPV of 97.1% (95% confidence interval (CI) 92.8-99.2) and a sensitivity of 88.2% (95% CI 82.0-92.9). In the Norwegian Patient Register, the PPV was 96.3% (95% CI 91.6-98.8) and the sensitivity was 85.6% (95% CI 79.0-90.8). The combined dataset of the Norwegian Myocardial Infarction Register and the Norwegian Patient Register had a PPV of 96.6% (95% CI 92.1-98.9) and a sensitivity of 91.5% (95% CI 85.9-95.4). CONCLUSION: MI diagnoses in both the Norwegian Myocardial Infarction Register and the Norwegian Patient Register were highly correct and complete, and each of the registers could be considered as endpoint sources for the Tromsø Study. A combination of the two national registers seemed, however, to represent the most comprehensive data source overall. The benefits of using data from national registers as endpoints in epidemiological studies include faster, less resource-intensive access to nationwide data and considerably lower loss to follow-up, compared to manual data collection in a limited geographical area.

Incidence and risk factors for major bleeding among patients undergoing percutaneous coronary intervention: Findings from the Norwegian Coronary Stent Trial (NORSTENT).

INTRODUCTION: Bleeding is a concern after percutaneous coronary intervention (PCI) and subsequent dual antiplatelet therapy (DAPT). We herein report the incidence and risk factors for major bleeding in the Norwegian Coronary Stent Trial (NORSTENT). MATERIALS AND METHODS: NORSTENT was a randomized, double blind, pragmatic trial among patients with acute coronary syndrome or stable coronary disease undergoing PCI during 2008-11. The patients (N = 9,013) were randomized to receive either a drug-eluting stent or a bare-metal stent, and were treated with at least nine months of DAPT. The patients were followed for a median of five years, with Bleeding Academic Research Consortium (BARC) 3-5 major bleeding as one of the safety endpoints. We estimated cumulative incidence of major bleeding by a competing risks model and risk factors through cause-specific Cox models. RESULTS: The 12-month cumulative incidence of major bleeding was 2.3%. Independent risk factors for major bleeding were chronic kidney disease, low bodyweight (< 60 kilograms), diabetes mellitus, and advanced age (> 80 years). A myocardial infarction (MI) or PCI during follow-up increased the risk of major bleeding (HR = 1.67, 95% CI 1-29-2.15). CONCLUSIONS: The 12-month cumulative incidence of major bleeding in NORSTENT was higher than reported in previous, explanatory trials. This analysis strengthens the role of chronic kidney disease, advanced age, and low bodyweight as risk factors for major bleeding among patients receiving DAPT after PCI. The presence of diabetes mellitus or recurrent MI among patients is furthermore a signal of increased bleeding risk. CLINICAL TRIAL REGISTRATION: Unique identifier NCT00811772; http://www.clinicaltrial.gov.

Does a history of cardiovascular disease or cancer affect mortality after SARS-CoV-2 infection? / Hva betyr tidligere hjerte- og karsykdom eller kreft for risiko for død etter påvist SARS-CoV-2?

BACKGROUND: Cardiovascular disease and cancer have been described as possible risk factors for COVID-19 mortality. The purpose of this study was to investigate whether a history of cardiovascular disease or cancer affects the risk of dying after a COVID-19 diagnosis in Norway. MATERIAL AND METHOD: Data were compiled from the Norwegian Surveillance System for Communicable Diseases, the Norwegian Cardiovascular Disease Registry and the Cancer Registry of Norway. Univariable and multivariable regression models were used to calculate both relative and absolute risk. RESULTS: In the first half of 2020, 8 809 people tested positive for SARS-CoV-2 and 260 COVID-19-associated deaths were registered. Increasing age, male sex (relative risk (RR): 1.5; confidence interval (CI): 1.2-2.0), prior stroke (RR: 1.5; CI: 1.0-2.1) and cancer with distant metastasis at the time of diagnosis (RR: 3.0; CI: 1.1-8.2) were independent risk factors for death after a diagnosis of COVID-19. After adjusting for age and sex, myocardial infarction, atrial fibrillation, heart failure, hypertension, and non-metastatic cancer were no longer statistically significant risk factors for death. INTERPRETATION: The leading risk factor for death among individuals who tested positive for SARS-CoV-2 was age. Male sex, and a previous diagnosis of stroke or cancer with distant metastasis were also associated with an increased risk of death after a COVID-19 diagnosis.

Influenza vaccination and risk for cardiovascular events: a nationwide self-controlled case series study.

BACKGROUND: US and European guidelines diverge on whether to vaccinate adults who are not at high risk for cardiovascular events against influenza. Here, we investigated the associations between influenza vaccination and risk for acute myocardial infarction, stroke and pulmonary embolism during the 2009 pandemic in Norway, when vaccination was recommended to all adults. METHODS: Using national registers, we studied all vaccinated Norwegian individuals who suffered AMI, stroke, or pulmonary embolism from May 1, 2009 through September 30, 2010. We defined higher-risk individuals as those using anti-diabetic, anti-obesity, anti-thrombotic, pulmonary or cardiovascular medications (i.e. individuals to whom vaccination was routinely recommended); all other individuals were regarded as having lower-risk. We estimated incidence rate ratios with 95% CI using conditional Poisson regression in the pre-defined risk periods up to 180 days following vaccination compared to an unexposed time-period, with adjustment for season or daily temperature. RESULTS: Overall, we observed lower risk for cardiovascular events following influenza vaccination. When stratified by baseline risk, we observed lower risk across all three outcomes in association with vaccination among higher-risk individuals. In this subgroup, relative risks were 0.72 (0.59-0.88) for AMI, 0.77 (0.59-0.99) for stroke, and 0.73 (0.45-1.19) for pulmonary embolism in the period 1-14 days following vaccination when compared to the background period. These associations remained essentially the same up to 180 days after vaccination. In contrast, the corresponding relative risks among subjects not using medications were 4.19 (2.69-6.52), 1.73 (0.91-3.31) and 2.35 (0.78-7.06). CONCLUSION: In this nationwide study, influenza vaccination was associated with overall cardiovascular benefit. This benefit was concentrated among those at higher cardiovascular risk as defined by medication use. In contrast, our results demonstrate no comparable inverse association with thrombosis-related cardiovascular events following vaccination among those free of cardiovascular medications at baseline. These results may inform the risk-benefit balance for universal influenza vaccination.

Completeness and correctness of acute myocardial infarction diagnoses in a medical quality register and an administrative health register.

Aims: Health registers are used for administrative purposes, disease surveillance, quality assessment, and research. The value of the registers is entirely dependent on the quality of their data. The aim of this study was to investigate and compare the completeness and correctness of the acute myocardial infarction (AMI) diagnosis in the Norwegian Myocardial Infarction Register and in the Norwegian Patient Register. Methods: All Norwegian patients admitted directly to St Olavs hospital, Trondheim University Hospital, Trondheim University Hospital from 1 July to 31 December 2012 and who had plasma levels of cardiac troponin T measured during their hospitalization (n=4835 unique individuals, n=5882 hospitalizations) were identified in the hospital biochemical database. A gold standard for AMI was established by evaluation of maximum troponin T levels and by review of the information in the medical records. Cases of AMI in the registers were classified as true positive, false positive, true negative, and false negative according to the gold standard. We calculated sensitivity, positive predictive value (PPV), specificity, and negative predictive value (NPV). Results: The Norwegian Myocardial Infarction Register had a sensitivity of 86.0% (95% confidence interval (CI) 82.8-89.3%), PPV of 97.9% (96.4-99.3%), and specificity of 99.9% and NPV of 98.9% (98.6-99.2%) (99.8-100%). The corresponding figures for the Norwegian Patient Register were 85.8% (95% CI 82.5-89.1%), 95.1% (92.9-97.2%), and 99.7% (99.5-99.8%) and 98.9% (98.6-99.2%), respectively. Both registers had a sensitivity higher than 95% when compared to hospital discharge diagnoses. The results were similar for men and women and for cases below and above 80 years of age. Conclusions: The Norwegian Myocardial Infarction Register and the Norwegian Patient Register are adequately complete and correct for administrative purposes, disease surveillance, quality assessment, and research.

Treatment of ST-elevation myocardial infarction - an observational study. / Behandling av hjerteinfarkt med ST-elevasjon ­ en observasjonsstudie.

BACKGROUND: ST-elevation myocardial infarction is treated with reperfusion, either in the form of primary percutaneous coronary intervention (PCI) or thrombolytic therapy. The choice of treatment depends on transport time to the nearest PCI centre. Norway's geography means that thrombolytic therapy will be appropriate for many patients. Irrespective of treatment choice, it is important to avoid delays. We wished to compare the outcomes of primary PCI and thrombolytic therapy in our healthcare region and to examine whether reperfusion therapy was administered within the recommended time window. MATERIAL AND METHOD: Using registry data and patient medical records, we compared the outcomes of primary PCI and thrombolytic therapy in cases of ST-elevation myocardial infarction in the Central Norway Regional Health Authority in the period 2015-16. The outcomes analysed were 30-day mortality, ejection fraction measured by echocardiography during the hospital stay, incidence of bleeding complications, and time from diagnosis to start of treatment. RESULTS: The study population comprised 648 patients with ST-elevation myocardial infarction. Of these, 382 were treated with primary PCI and 266 received thrombolytic therapy. The 30-day mortality was 5.5 % in the primary PCI group and 5.6 % in the thrombolysis group (p = 1.0). There were no significant differences in ejection fraction and no cases of serious bleeding. In 45 % of the total population, reperfusion therapy was started later than recommended in guidelines. INTERPRETATION: There was no statistically significant difference in mortality or ejection fraction when comparing primary PCI and thrombolytic therapy in an unselected population with ST-elevation myocardial infarction. Many patients experienced delayed start of treatment . It is important to take action to reduce delays at all stages of the therapeutic chain. Thrombolytic therapy should be considered when it is unclear whether transport time to a PCI centre will exceed that recommended in guidelines.

Longitudinal and secular trends in total cholesterol levels and impact of lipid-lowering drug use among Norwegian women and men born in 1905-1977 in the population-based Tromsø Study 1979-2016.

OBJECTIVES: Elevated blood cholesterol is a modifiable risk factor for cardiovascular disease. Cholesterol level surveillance is necessary to study population disease burden, consider priorities for prevention and intervention and understand the effect of diet, lifestyle and treatment. Previous studies show a cholesterol decline in recent decades but lack data to follow individuals born in different decades throughout life. METHODS: We investigated changes in age-specific and birth cohort-specific total cholesterol (TC) levels in 43 710 women and men born in 1905-1977 (aged 20-95 years at screening) in the population-based Tromsø Study. Fifty-nine per cent of the participants had more than one and up to six repeated TC measurements during 1979-2016. Linear mixed models were used to test for time trends. RESULTS: Mean TC decreased during 1979-2016 in both women and men and in all age groups. The decrease in TC in age group 40-49 years was 1.2 mmol/L in women and 1.0 mmol/L in men. Both the 80th and the 20th percentile of the population TC distribution decreased in both sexes and all age groups. Longitudinal analysis showed that TC increased with age to a peak around middle age followed by a decrease. At any given age, TC significantly decreased with increase in year born. Lipid-lowering drug use was rare in 1994, increased thereafter, but was low (<3% in women and <5% in men) among those younger than 50 years in all surveys. Between 1994 and 2016, lipid-lowering drug treatment in individuals 50 years and older explained 21% and 28% of the decrease in TC levels in women and men, respectively. CONCLUSIONS: We found a substantial decrease in mean TC levels in the general population between 1979 and 2016 in all age groups. In birth cohorts, TC increased with age to a peak around middle age followed by a decrease.

Data on gender contrasts in the risk of incident myocardial infarction by age. The Tromsø Study 1979-2012.

The data presented in this article relate to the research article entitled "Risk of incident myocardial infarction by gender: Interactions with serum lipids, blood pressure and smoking. The Tromsø Study 1979-2012" (Albrektsen et al., 2017) [1]. Data quantify the gender differences in the risk of myocardial infarction (MI) in terms of incidence rate ratios (IRR), in subgroups defined by serum lipids, blood pressure and smoking among persons aged 35-54 years, 55-74 years and 75-94 years, respectively. Data also describe the age- and gender-specific linear associations with the coronary heart disease (CHD) risk factors. IRRs for combined categories of age, gender and a CHD risk factor, with each category compared to the same reference group, are also shown. IRRs were calculated as estimates of relative risk in Poisson regression analyses of person-years at risk. Among 33,859 individuals at risk, a total of 622, 1308 and 816 were diagnosed with MI at ages 35-54, 55-74 and 75-94 years, respectively.

Risk of incident myocardial infarction by gender: Interactions with serum lipids, blood pressure and smoking. The Tromsø Study 1979-2012.

BACKGROUND AND AIMS: Overall, men have roughly twice the risk of myocardial infarction (MI) compared to women, but what causes this contrast is unclear. Identification of subgroups where the gender contrast in risk is particularly low or high, may provide new insight. In the search for such subgroups, we focus on gender-specific effects of established coronary heart disease (CHD) risk factors. Heterogeneity across age groups is also explored. METHODS: Population-based prospective study from Tromsø, Norway, comprising 33,859 individuals (51% women); 2746 individuals (854 women) received a diagnosis of MI during follow-up at ages 35-94 years. Incidence rate ratios (IRR) were calculated as estimates of relative risk in Poisson regression analyses. RESULTS: The association between total cholesterol and risk of MI was stronger for men than women, and IRR for men vs. women accordingly increased with increasing cholesterol, but the risk was higher for men in all subgroups (IRR in range 1.63-3.27), except among older people with low cholesterol levels. The adverse effect of increasing blood pressure (BP) was stronger for women, and IRR for gender diminished with increasing systolic (from 3.90 to 1.38) and diastolic BP (from 2.87 to 1.54). The gender contrast in risk was also substantially reduced in smokers ≥75 years. Associations with high-density lipoprotein cholesterol (HDL-C) did not differ between genders. CONCLUSIONS: Gender heterogeneity in associations with total cholesterol but not HDL-C indicates gender differences in associations with non-HDL-C. The stronger association with BP in women may relate to more severe hypertension-induced left ventricular hypertrophy.

Lifelong Gender Gap in Risk of Incident Myocardial Infarction: The Tromsø Study.

Importance: It is not clear to what extent the higher incidence of coronary heart disease (CHD) in men vs women is explained by differences in risk factor levels because few studies have presented adjusted risk estimates for sex. Moreover, the increase in risk of CHD in postmenopausal women, possibly hormone related, may eventually eliminate the sex contrast in risk, but age-specific risk estimates are scarce. Objective: To quantify the difference in risk of incident myocardial infarction (MI) between men and women. Design, Setting and Participants: Population-based prospective study from Tromsø, Norway, comprising 33 997 individuals (51% women). Median follow-up time during ages 35 to 102 years was 17.6 years. Incidence rates (IRs) and incidence rate ratios (IRRs, relative risk) of MI were calculated in Poisson regression analysis of person-years at risk. The data analysis was performed in November 2015. Exposures: Sex, age, birth cohort, serum lipid levels, blood pressure, lifestyle factors, diabetes. Main Outcomes and Measures: Incident MI. Results: A total of 2793 individuals (886 women) received a diagnosis of MI during follow-up in the period 1979 through 2012. The IR increased with age in both sexes, with lower rates for women until age 95 years. Adjusted for age and birth cohort, the overall IRR for men vs women was 2.72 (95% CI, 2.50-2.96). Adjustment for high-density lipoprotein cholesterol and total cholesterol levels had the strongest impact on the risk estimate for sex, followed by diastolic blood pressure and smoking. However, the sex difference remained substantial even after adjustment for these factors (IRR, 2.07; 95% CI, 1.89-2.26). Men had higher risk throughout life, but the IRRs decreased with age (3.64 [95% CI, 2.85-4.65], 2.00 [95% CI, 1.76-2.28], and 1.66 [95% CI, 1.42-1.95] for age groups 35-54, 55-74, and 75-94 years, respectively). Adjustment for systolic blood pressure, diabetes, body mass index, and physical activity had no notable impact. Conclusions and Relevance: The observed sex contrast in risk of MI cannot be explained by differences in established CHD risk factors. The gender gap persisted throughout life but declined with age as a result of a more pronounced flattening of risk level changes in middle-aged men. The minor changes in IRs when moving from premenopausal to postmenopausal age in women make it unlikely that changes in female hormone levels influence the risk of MI.

Interrater reliability of a national acute myocardial infarction register.

BACKGROUND: Disease-specific registers may be used for measuring and improving healthcare and patient outcomes, and for disease surveillance and research, provided they contain valid and reliable data. The aim of this study was to assess the interrater reliability of all variables in a national myocardial infarction register. METHODS: We randomly selected 280 patients who had been enrolled from 14 hospitals to the Norwegian Myocardial Infarction Register during the year 2013. Experienced audit nurses, who were blinded to the data about the 280 patients already in the register, completed the Norwegian Myocardial Infarction paper forms for 240 patients by review of medical records. We then extracted all registered data on the same patients from the Norwegian Myocardial Infarction Register. To compare the interrater reliability between the register and the audit nurses, we calculated intraclass correlations coefficient for continuous variables, Cohen's kappa and Gwet's first agreement coefficient (AC1) for nominal variables, and quadratic weighted Cohen's kappa and Gwet's second AC for ordinal variables. RESULTS: We found excellent (AC1 >0.80) or good (AC1 0.61-0.80) agreement for most variables, including date and time variables, medical history, investigations and treatments during hospitalization, medication at discharge, and ST-segment elevation or non-ST-segment elevation acute myocardial infarction. However, only moderate agreement (AC1 0.41-0.60) was found for family history of coronary heart disease, diagnostic electrocardiography, and complications during hospitalization, whereas fair agreement (AC1 0.21-0.40) was found for acute myocardial infarction location. A high percentage of missing data was found for symptom onset, family history, body mass index, infarction location, and new Q-wave. CONCLUSION: Most variables in Norwegian Myocardial Infarction Register had excellent or good reliability. However, some important variables had lower reliability than expected or had missing data. Precise definitions of data elements and proper training of data abstractors are necessary to ensure that clinical registries contain valid and reliable data.

Trends in Modifiable Risk Factors Are Associated With Declining Incidence of Hospitalized and Nonhospitalized Acute Coronary Heart Disease in a Population.

BACKGROUND: Few studies have used individual person data to study whether contemporary trends in the incidence of coronary heart disease are associated with changes in modifiable coronary risk factors. METHODS AND RESULTS: We identified 29 582 healthy men and women ≥25 years of age who participated in 3 population surveys conducted between 1994 and 2008 in Tromsø, Norway. Age- and sex-adjusted incidence rates were calculated for coronary heart disease overall, out-of-hospital sudden death, and hospitalized ST-segment-elevation and non-ST-segment-elevation myocardial infarction. We measured coronary risk factors at each survey and estimated the relationship between changes in risk factors and changes in incidence trends. A total of 1845 participants had an incident acute coronary heart disease event during 375 064 person-years of follow-up from 1994 to 2010. The age- and sex-adjusted incidence of total coronary heart disease decreased by 3% (95% confidence interval, 2.0-4.0; P<0.001) each year. This decline was driven by decreases in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in coronary risk factors accounted for 66% (95% confidence interval, 48-97; P<0.001) of the decline in total coronary heart disease. Favorable changes in cholesterol contributed 32% to the decline, whereas blood pressure, smoking, and physical activity each contributed 14%, 13%, and 9%, respectively. CONCLUSIONS: We observed a substantial decline in the incidence of coronary heart disease that was driven by reductions in out-of-hospital sudden death and hospitalized ST-segment-elevation myocardial infarction. Changes in modifiable coronary risk factors accounted for 66% of the decline in coronary heart disease events.