Validity of register data on acute myocardial infarction and acute stroke: the Skaraborg Hypertension Project

Patient characteristics and safety outcomes in new users of ticagrelor and clopidogrel-An observational cohort study in Sweden

PURPOSE

We aimed to describe characteristics of new users of ticagrelor or clopidogrel following a recent coronary event, and to compare incidences of selected safety outcomes.

METHODS

This observational cohort study used data from national Swedish registers. Patients first dispensed ticagrelor or clopidogrel (June 2011-December 2013) were identified from the Prescribed Drug Register and followed until censoring or 31 December 2014. Cohorts were restricted to patients with a recent coronary event-related hospital contact identified in the Patient Register.

RESULTS

The study included 45 987 unique, naïve users of ticagrelor (73% men; mean age 66 years) or clopidogrel (69% men; mean age 69 years). Corresponding to indication, diagnoses before initiation were acute coronary syndrome (93%), myocardial infarction (76%), and percutaneous coronary intervention (69%). The most common medications used in the year before initiation of study therapy were antithrombotic agents (clopidogrel 62%, ticagrelor 43%), mainly low-dose acetylsalicylic acid. Ticagrelor users had a higher incidence (per 1000 person-years) of respiratory bleeding (24.6 [95% confidence interval (CI): 22.1-27.3]; vs clopidogrel users: 14.4 [13.1-15.8]) and dyspnea (25.9 [23.3-28.7]; vs clopidogrel users: 16.8 [15.4-18.4]). Epistaxis accounted for 83-93% of respiratory bleeds. Adjusted analyses found increased risks of gout and acute renal failure with ticagrelor.

CONCLUSIONS

Clopidogrel users were older with a higher prevalence of concomitant medications than ticagrelor users. Our study showed increased incidences of dyspnea and respiratory bleeding (mainly epistaxis) among current ticagrelor users compared with clopidogrel users, and increased risks of gout and acute renal failure after adjustment.

Major adverse cardiovascular event definitions used in observational analysis of administrative databases: a systematic review

Background

Major adverse cardiovascular events (MACE) are increasingly used as composite outcomes in randomized controlled trials (RCTs) and observational studies. However, it is unclear how observational studies most commonly define MACE in the literature when using administrative data.

Methods

We identified peer-reviewed articles published in MEDLINE and EMBASE between January 1, 2010 to October 9, 2020. Studies utilizing administrative data to assess the MACE composite outcome using International Classification of Diseases 9th or 10th Revision diagnosis codes were included. Reviews, abstracts, and studies not providing outcome code definitions were excluded. Data extracted included data source, timeframe, MACE components, code definitions, code positions, and outcome validation.

Results

A total of 920 articles were screened, 412 were retained for full-text review, and 58 were included. Only 8.6% (n = 5/58) matched the traditional three-point MACE RCT definition of acute myocardial infarction (AMI), stroke, or cardiovascular death. None matched four-point (+unstable angina) or five-point MACE (+unstable angina and heart failure). The most common MACE components were: AMI and stroke, 15.5% (n = 9/58); AMI, stroke, and all-cause death, 13.8% (n = 8/58); and AMI, stroke and cardiovascular death 8.6% (n = 5/58). Further, 67% (n = 39/58) did not validate outcomes or cite validation studies. Additionally, 70.7% (n = 41/58) did not report code positions of endpoints, 20.7% (n = 12/58) used the primary position, and 8.6% (n = 5/58) used any position.

Conclusions

Components of MACE endpoints and diagnostic codes used varied widely across observational studies. Variability in the MACE definitions used and information reported across observational studies prohibit the comparison, replication, and aggregation of findings. Studies should transparently report the administrative codes used and code positions, as well as utilize validated outcome definitions when possible.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01440-5.

Validation of myocardial infarction diagnosis in patients with congenital heart disease in Sweden

Background

The population of adults with congenital heart disease (CHD) is growing, and increasingly more patients with CHD reach older ages. Patients with CHD are at an increased risk of myocardial infarction (MI) with increased age. Diagnosing MI in patients with CHD can be challenging in clinical practice owing to a high prevalence of aberrant electrocardiograms, ventricular hypertrophy, and heart failure, among other factors. The National Swedish Patient Register (NPR) is widely used in epidemiological studies; however, MI diagnoses specifically in patients with CHD have never been validated in the NPR.

Methods

We contacted hospitals and medical archive services to request medical records for 249 patients, born during 1970–2012, with both CHD and MI diagnoses and who were randomly selected from the NPR by the Swedish National Board of Health and Welfare. Follow-up was until 2015. We performed a medical chart review to validate the MI diagnoses; we also validated CHD diagnoses to ensure that only patients with confirmed CHD diagnoses were included in the MI validation process.

Results

We received medical records for 96.4% (n = 238/249) of patients for validation of CHD diagnoses. In total, 74.8% (n = 178/238) had a confirmed CHD diagnosis; of these, 70.2% (n = 167) had a fully correct CHD diagnosis in the NPR; a further 4.6% (n = 11) had a CHD diagnosis, but it was misclassified. MI diagnoses were validated in 167 (93.8%) patients with confirmed CHD. Of the patients with confirmed CHD, 88.0% (n = 147/167) had correct MI diagnoses. Patients with non-complex CHD diagnoses had more correct MI diagnoses than patients with complex CHD (91.0%, n = 131 compared with 69.6%, n = 16). The main cause for incorrect MI diagnoses was typographical error, contributing to 50.0% of the incorrect diagnoses.

Conclusions

The validity of MI diagnoses in patients with confirmed CHD in the NPR is high, with nearly 9 of 10 MI diagnoses being correct (88.0%). MI in patients with CHD can safely be studied using the NPR.

Validity of Acute Cardiovascular Outcome Diagnoses Recorded in European Electronic Health Records: A Systematic Review

BACKGROUND

Electronic health records are widely used in cardiovascular disease research. We appraised the validity of stroke, acute coronary syndrome and heart failure diagnoses in studies conducted using European electronic health records.

METHODS

Using a prespecified strategy, we systematically searched seven databases from dates of inception to April 2019. Two reviewers independently completed study selection, followed by partial parallel data extraction and risk of bias assessment. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value estimates were narratively synthesized and heterogeneity between sensitivity and PPV estimates were assessed using I2.

RESULTS

We identified 81 studies, of which 20 validated heart failure diagnoses, 31 validated acute coronary syndrome diagnoses with 29 specifically recording estimates for myocardial infarction, and 41 validated stroke diagnoses. Few studies reported specificity or negative predictive value estimates. Sensitivity was ≤66% in all but one heart failure study, ≥80% for 91% of myocardial infarction studies, and ≥70% for 73% of stroke studies. PPV was ≥80% in 74% of heart failure, 88% of myocardial infarction, and 70% of stroke studies. PPV by stroke subtype was variable, at ≥80% for 80% of ischaemic stroke but only 44% of haemorrhagic stroke. There was considerable heterogeneity (I2 >75%) between sensitivity and PPV estimates for all diagnoses.

CONCLUSION

Overall, European electronic health record stroke, acute coronary syndrome and heart failure diagnoses are accurate for use in research, although validity estimates for heart failure and individual stroke subtypes were lower. Where possible, researchers should validate data before use or carefully interpret the results of previous validation studies for their own study purposes.

Can the Plasma Concentration Ratio of Triglyceride/High-Density Lipoprotein Cholesterol Identify Individuals at High Risk of Cardiovascular Disease During 40-Year Follow-Up?

BACKGROUND

The plasma concentration ratio of triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) is a simple way to estimate insulin resistance. We aimed to evaluate the TG/HDL-C ratio as a simple clinical way to identify apparently healthy individuals with insulin resistance and enhanced risk of future cardiovascular disease (CVD).

METHODS

One thousand seven hundred twenty men, aged 50 years, free from diabetes and CVD when evaluated at baseline in 1970-1974 were followed for 40 years regarding incident CVD (myocardial infarction and/or ischemic stroke, n = 576).

RESULTS

Participants with a high TG/HDL-C ratio (highest quartile >1.8) at baseline were more insulin resistant, with a significantly more adverse cardiometabolic risk profile (P < 0.001) at baseline, compared with those with a lower ratio. This group also showed an increased risk of CVD [hazard ratio, HR 1.47 (95% confidence interval 1.26-1.93) P < 0.001]. Fourteen percent of subjects with metabolic syndrome, in whom insulin resistance is increased, were also at enhanced CVD risk [HR 1.75 (1.42-2.16) P < 0.001].

CONCLUSIONS

Twenty-five percent of apparently healthy 50-year-old men with the highest TG/HDL-C plasma concentration ratio had a significantly more adverse cardiometabolic profile at baseline, and developed more CVD over the next 40 years, compared with those not meeting this cut point. Determining the TG/HDL-C ratio in middle-aged men provided a simple and potentially clinically useful way to identify increased risk of developing CVD in persons free of diabetes or manifest CVD.

Increased risk for dementia both before and after stroke: A population-based study in women followed over 44 years

INTRODUCTION

Longitudinal studies are needed to understand the long-term associations between stroke and dementia.

METHODS

A population sample of 1460 women without stroke or dementia at baseline was followed over 44 years, from 1968 to 2012. Information on stroke and dementia was obtained from neuropsychiatric examinations, key-informant interviews, hospital registry, and medical records.

RESULTS

During 44 years follow-up, 362 women developed stroke and 325, dementia. The age-specific incidence of the two disorders was similar. The incidence of dementia was higher in those with stroke than among those without (33.7% vs. 18.5%; age-adjusted hazard ratio 1.44, 95% confidence interval 1.15-1.81). The increased risk of dementia started already 5 years before stroke, was highest 1 year after stroke, and continued more than 11 years after stroke.

DISCUSSION

There is an increased risk for dementia both before and after stroke. This has implications for understanding the relation between the two disorders and for prevention of dementia and stroke.

Determination of age-specific and sex-specific familial risks for the different manifestations of venous thromboembolism: A nationwide family study in Sweden

This nationwide study aimed to determine whether differences exist in age-specific and sex-specific familial risks for pulmonary embolism (PE), venous thrombosis of the lower limbs (VT) and other forms of venous thromboembolism (OVTE) among offspring, siblings and spouses of affected individuals. The Swedish Multi-Generation Register was linked to the Hospital Discharge Register data for the period 1987–2007. Standardised incidence ratios (SIRs) were calculated for individuals whose relatives were hospitalised for venous thromboembolism (VTE), as determined by the International Classification of Diseases (ICD), and those whose relatives were unaffected by VTE. The total number of hospitalised VTE patients was 45,362. All VTE patients were categorised as PE, VT or OVTE according to ICD at first hospitalisation. For example, the parental SIRs for PE, VT and OVTE in offspring at age 10–19 years were 2.89 (95% CI 1.48–5.06), 4.99 (95% CI 3.22–6.10) and 3.89 (95% CI 2.51–5.75), respectively. The low spousal risks of PE (1.08; 95% CI 1.02–1.13), VT (1.06; 95% CI 1.011.12) and OVTE (1.07; 95% CI 1.00–1.15) suggest the familial risks to be largely genetic. In both men and women, familial relative risks were increased for all the different manifestations of VTE with the exception of those older than 70 years. Familial history is a risk indicator in both sexes, and is potentially useful for clinical risk assessment for the different manifestations of VTE.

Decreasing prevalence of dementia in 85-year olds examined 22 years apart: the influence of education and stroke

Individuals aged 80 years and older constitute the fastest growing segment of the population worldwide, leading to an expected increase in dementia cases. Education level and treatment of vascular risk factors has increased during the last decades. We examined whether this has influenced the prevalence of dementia according to DSM-III-R using population-based samples of 85-year-olds (N = 1065) examined with identical methods 1986–87 and 2008–10. The prevalence of dementia was 29.8% in 1986–87 and 21.7% in 2008–10 (OR 0.66; 95%-CI: 0.50–0.86). The decline was mainly observed for vascular dementia. The proportion with more than basic education (25.2% and 57.7%), and the prevalence of stroke (20% and 30%) increased, but the odds ratio for dementia with stroke decreased from 4.3 to 1.8 (interaction stroke*birth cohort; p = 0.008). In a logistic regression, education (OR 0.70; 95%-CI 0.51–0.96), stroke (OR 3.78; 95%-CI 2.28–6.29), interaction stroke*birth cohort (OR 0.50; 95%-CI 0.26–0.97), but not birth cohort (OR 0.98; 95%-CI 0.68–1.41), were related to prevalence of dementia. Thus, the decline in dementia prevalence was mainly explained by higher education and lower odds for dementia with stroke in later born birth cohorts. The findings may be related to an increased cognitive reserve and better treatment of stroke in later-born cohorts.

Predictive value of stroke discharge diagnoses in the Danish National Patient Register

AIMS

To determine the positive predictive values for stroke discharge diagnoses, including subarachnoidal haemorrhage, intracerebral haemorrhage and cerebral infarction in the Danish National Patient Register.

METHODS

Participants in the Danish cohort study Diet, Cancer and Health with a stroke discharge diagnosis in the National Patient Register between 1993 and 2009 were identified and their medical records were retrieved for validation of the diagnoses.

RESULTS

A total of 3326 records of possible cases of stroke were reviewed. The overall positive predictive value for stroke was 69.3% (95% confidence interval (CI) 67.8-70.9%). The predictive values differed according to hospital characteristics, with the highest predictive value of 87.8% (95% CI 85.5-90.1%) found in departments of neurology and the lowest predictive value of 43.0% (95% CI 37.6-48.5%) found in outpatient clinics.

CONCLUSIONS

The overall stroke diagnosis in the Danish National Patient Register had a limited predictive value. We therefore recommend the critical use of non-validated register data for research on stroke. The possibility of optimising the predictive values based on more advanced algorithms should be considered.

Genetic susceptibility to cardiovascular disease and risk of dementia

Several studies have shown cardiovascular disease (CVD) to be associated with dementia, but it is not clear whether CVD per se increases the risk of dementia or whether the association is due to shared risk factors. We tested how a genetic risk score (GRS) for coronary artery disease (CAD) affects dementia risk after CVD in 13 231 Swedish twins. We also utilized summarized genome-wide association data to study genetic overlap between CAD and Alzheimer´s disease (AD), and additionally between shared risk factors and each disease. There was no direct effect of a CAD GRS on dementia (hazard ratio 0.99, 95% confidence interval (CI): 0.98-1.01). However, the GRS for CAD modified the association between CVD and dementia within 3 years of CVD diagnosis, ranging from a hazard ratio of 1.59 (95% CI: 1.05-2.41) in the first GRS quartile to 1.91 (95% CI: 1.28-2.86) in the fourth GRS quartile. Using summary statistics, we found no genetic overlap between CAD and AD. We did, however, find that both AD and CAD share a significant genetic overlap with lipids, but that the overlap arose from clearly distinct gene clusters. In conclusion, genetic susceptibility to CAD was found to modify the association between CVD and dementia, most likely through associations with shared risk factors.

Association between antithrombotic treatment and hemorrhagic stroke in patients with atrial fibrillation-a cohort study in primary care

Objective

The objective of this study was to study the association between antithrombotic treatment and risk of hemorrhagic stroke (HS) in patients with atrial fibrillation (AF) treated in primary health care.

Methods

Study population included all adults (n = 12,215) 45 years and older diagnosed with AF at 75 primary care centers in Sweden 2001–2007. Outcome was defined as a first hospital episode with a discharge episode of HS after the AF diagnosis. Association between HS and persistent treatment with antithrombotic agents (warfarin, acetylsalicylic acid (ASA), clopidogrel) was explored using Cox regression analysis, with hazard ratios (HRs) and 95 % CIs. Adjustment was made for age, socioeconomic status, and co-morbid cardiovascular conditions.

Results

During a mean of 5.8 years (SD 2.4) of follow-up, 162 patients (1.3 %; 67 women and 95 men) with HS were recorded. The adjusted risk associated with persistent warfarin treatment compared to no antithrombotic treatment consistently showed no increased HS risk, HR for women 0.53 (95 % CI 0.23–1.27) and for men 0.55 (95 % CI 0.29–1.04); corresponding HRs for ASA were, for women, 0.45 (95 % CI 0.14–1.44) and, for men, 0.56 (95 % CI 0.24–1.29).

Conclusions

In this clinical setting, we found no evidence pointing to an increased risk of HS with antithrombotic treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-016-2152-8) contains supplementary material, which is available to authorized users.

Measures of prevalence: which healthcare registers are applicable?

Aims: This study analyses the applicability of some of the registers used within the healthcare system for estimations of disease prevalence .The study focuses on the diagnoses of asthma, diabetes mellitus, chronic bronchitis/emphysema, hypertensive disease, and cerebrovascular disease. Methods: The study population comprised all inhabitants ( n=20,037) in the municipality of Tierp on 31 December 1996. Diagnostic information was collected from primary healthcare and occupational healthcare in the municipality of Tierp and from inpatient and outpatient units at the hospitals in Uppsala County. The proportion of registered patients in the different registers was calculated in relation to the total number of patients who had been registered during 1996 with the selected diagnoses . Results: In the primary healthcare register, between 67% ( cerebrovascular disease) and 85% ( asthma) of all patients with selected diagnoses could be identified. A search on the inpatient care register ( Hospital Discharge Register) led to the identification of between 8% ( hypertensive disease) and 53% ( cerebrovascular disease) of the patients. Conclusions: For all of the examined diagnoses, most patients could be identified in the primary healthcare register. Register data from both primary healthcare and inpatient and outpatient care at hospital are needed to make reasonable estimates of prevalence.

Circulating concentrations of endothelin-1 predict coronary heart disease in women but not in men: a longitudinal observational study in the Vara-Skövde Cohort

BACKGROUND

The vasoconstricting peptide endothelin-1 has been proposed to be a marker of cardiovascular disease. Our aim was to investigate whether circulating endothelin-1 levels predict coronary heart disease (CHD) in Sweden.

METHODS

In 2002-2005, 2816 adult participants (30-74 years) were randomly selected from two municipalities in south-western Sweden. Cardiovascular risk factors and endothelin-1 levels were assessed at baseline, and incident CHD was followed-up in all participants through 2011. After exclusion of 50 participants due to known CHD at baseline and 21 participants because of unsuccessful analysis of endothelin-1, 2745 participants were included in the study. In total, 72 CHD events (52 in men and 20 in women) were registered during the follow-up time.

RESULTS

We showed that baseline circulating endothelin-1 levels were higher in women with incident CHD than in women without CHD (3.2 pg/ml, SE: 0.36 vs 2.4 pg/ml, SE: 0.03, p = 0.003) whereas this difference was not observed in men (2.3 pg/ml, SE: 0.16 vs 2.3 pg/ml, SE: 0.04, p = 0.828). An age-adjusted Cox proportional regression analysis showed an enhanced risk of CHD with increasing baseline endothelin-1 levels in women (hazard ratio (HR) = 1.51, 95 % CI = 1.1-2.1, p = 0.015) but not in men (HR = 0.98, 95 % CI = 0.8-1.2, p = 0.854). Furthermore, the predictive value of endothelin-1 for incident CHD in women was still significant after adjustments for age, HOMA-IR, apolipoprotein (apo)B/apoA1 and smoking (HR = 1.53, CI = 1.1-1.2, p = 0.024).

CONCLUSION

Circulating endothelin-1 levels may predict CHD in women.

Family history of venous thromboembolism is a risk factor for venous thromboembolism in combined oral contraceptive users: a nationwide case-control study

BACKGROUND

The aim was to assess the risk of venous thromboembolism (VTE) associated with use of combined oral contraceptives (COCs) in women with a family history of VTE.

METHODS

The study is a Swedish nationwide case-control study based on the Multigeneration register, the Swedish Hospital Discharge Register, the Outpatient Care Register, and the Swedish Prescribed Drug Register. Cases (n = 2,311) were non-pregnant Swedish women aged 15-49 with first VTE diagnoses between January 2006 and December 2010. Five controls without VTE were matched to each case on age and education level. Conditional logistic regression examined the associations with VTE with determination of odds ratio (OR) for first VTE diagnosis. Effect modification was assessed by interaction testing.

RESULTS

Both among controls (14.6 % vs. 4.5 %; p < 0.0001) and cases (27.2 % vs. 8.8 %; p < 0.0001) COC use was more common in women without a family history of VTE compared with women with a family history of VTE. In a multivariate conditional logistic regression model the OR for VTE was 2.53 (95 % CI 2.23-2.87) for COC users and 2.38 (2.09-2.71) for individuals with a family history of VTE. The OR for VTE for COC users with a family history of VTE was 6.02 (5.02-7.22). There was no significant interaction between family history of VTE and COC use (OR 0.92, 0.57-1.46).

CONCLUSIONS

Family history of VTE is a risk factor for VTE in women using COCs. The low prevalence of COC use among women with a family history of VTE suggests that family history of VTE is considered when COCs are prescribed in Sweden. The present study may therefore even underestimate the importance of family history of VTE. The lack of interaction indicates that the risk of COC use in women with family history of VTE is determined by the product of the ORs for family history and COC use.

Validity of Diagnostic Codes for Acute Stroke in Administrative Databases: A Systematic Review

OBJECTIVE

To conduct a systematic review of studies reporting on the validity of International Classification of Diseases (ICD) codes for identifying stroke in administrative data.

METHODS

MEDLINE and EMBASE were searched (inception to February 2015) for studies: (a) Using administrative data to identify stroke; or (b) Evaluating the validity of stroke codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), or Kappa scores) for stroke, or data sufficient for their calculation. Additional articles were located by hand search (up to February 2015) of original papers. Studies solely evaluating codes for transient ischaemic attack were excluded. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

Seventy-seven studies published from 1976-2015 were included. The sensitivity of ICD-9 430-438/ICD-10 I60-I69 for any cerebrovascular disease was ≥ 82% in most [≥ 50%] studies, and specificity and NPV were both ≥ 95%. The PPV of these codes for any cerebrovascular disease was ≥ 81% in most studies, while the PPV specifically for acute stroke was ≤ 68%. In at least 50% of studies, PPVs were ≥ 93% for subarachnoid haemorrhage (ICD-9 430/ICD-10 I60), 89% for intracerebral haemorrhage (ICD-9 431/ICD-10 I61), and 82% for ischaemic stroke (ICD-9 434/ICD-10 I63 or ICD-9 434&436). For in-hospital deaths, sensitivity was 55%. For cerebrovascular disease or acute stroke as a cause-of-death on death certificates, sensitivity was ≤ 71% in most studies while PPV was ≥ 87%.

CONCLUSIONS

While most cases of prevalent cerebrovascular disease can be detected using 430-438/I60-I69 collectively, acute stroke must be defined using more specific codes. Most in-hospital deaths and death certificates with stroke as a cause-of-death correspond to true stroke deaths. Linking vital statistics and hospitalization data may improve the ascertainment of fatal stroke.

Low concentrations of serum testosterone predict acute myocardial infarction in men with type 2 diabetes mellitus

BACKGROUND

The aim of the present study was to investigate the associations between endogenous testosterone concentrations and the incidence of acute myocardial infarction (AMI) in men and women with and without type 2 diabetes.

METHODS

The study comprised 1109 subjects ≥40 years of age (mean age 62 ± 12 years) participating in a baseline survey in Sweden in 1993-94. Information about smoking habits and physical activity was obtained using validated questionnaires. Serum concentrations of testosterone and sex hormone-binding globulin (SHBG) were obtained using radioimmunoassay. Diagnosis of type 2 diabetes was based on WHO's 1985 criteria. Individual patient information on incident AMI was ascertained by record linkage with national inpatient and mortality registers from baseline through 2011.

RESULTS

The prevalence of type 2 diabetes at baseline was 10.0% in men and 7.5% in women. During a mean follow-up of 14.1 years (±5.3), there were 74 events of AMI in men and 58 in women. In age-adjusted Cox models, a significant inverse association between concentrations of testosterone and AMI-morbidity was found in men with type 2 diabetes (HR = 0.86 CI (0.75-0.98)). In a final model also including waist-to-hip ratio, systolic blood pressure, total cholesterol and active smoking, the association still remained statistically significant (HR = 0.754 CI (0.61-0.92)).

CONCLUSION

Low concentrations of testosterone predicted AMI in men with type 2 diabetes independent of other risk factors. Trials with testosterone investigating the effect regarding cardiovascular outcome are still lacking. Future trials in this field should take into account a modification effect of diabetes.

Validation of Stroke Diagnosis in the National Registry of Hospitalized Patients in the Czech Republic

BACKGROUND

Stroke is a common cause of mortality and morbidity in Eastern Europe. However, detailed epidemiological data are not available. The National Registry of Hospitalized Patients (NRHOSP) is a nationwide registry of prospectively collected data regarding each hospitalization in the Czech Republic since 1998. As a first step in the evaluation of stroke epidemiology in the Czech Republic, we validated stroke cases in NRHOSP.

METHODS

Any hospital in the Czech Republic with a sufficient number of cases was included. We randomly selected 10 of all 72 hospitals and then 50 patients from each hospital in 2011 stratified according to stroke diagnosis (International Classification of Diseases Tenth Revision [ICD-10] cerebrovascular codes I60, I61, I63, I64, and G45). Discharge summaries from hospitalization were reviewed independently by 2 reviewers and compared with NRHOSP for accuracy of discharge diagnosis. Any disagreements were adjudicated by a third reviewer.

RESULTS

Of 500 requested discharge summaries, 484 (97%) were available. Validators confirmed diagnosis in NRHOSP as follows: transient ischemic attack (TIA) or any stroke type in 82% (95% confidence interval [CI], 79-86), any stroke type in 85% (95% CI, 81-88), I63/cerebral infarction in 82% (95% CI, 74-89), I60/subarachnoid hemorrhage in 91% (95% CI, 85-97), I61/intracerebral hemorrhage in 91% (95% CI, 85-96), and G45/TIA in 49% (95% CI, 39-58). The most important reason for disagreement was use of I64/stroke, not specified for patients with I63.

CONCLUSIONS

The accuracy of coding of the stroke ICD-10 codes for subarachnoid hemorrhage (I60) and intracerebral hemorrhage (I61) included in a Czech Republic national registry was high. The accuracy of coding for I63/cerebral infarction was somewhat lower than for ICH and SAH.

Perinatal risk factors for premature ischaemic heart disease in a Swedish national cohort

OBJECTIVE

Several studies have reported associations between restricted fetal development, as shown by birth weight or birth length, and later ischaemic heart disease (IHD). However, few studies have examined the importance of these perinatal factors when taking into account gestational age at birth, hereditary factors, sociodemographic factors and comorbidities. This study investigated the importance of perinatal risk factors for premature IHD and myocardial infarction (MI) in a large Swedish cohort.

SETTING AND PARTICIPANTS

National cohort study of 1,970,869 individuals who were live-born in Sweden in 1973 through 1992, and followed up to 2010 (ages 18-38 years).

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcome was IHD, and the secondary outcome was MI.

RESULTS

A total of 668 individuals were diagnosed with IHD in 18.8 million person-years of follow-up. After adjusting for gestational age at birth, sociodemographic factors, comorbidities and family history of IHD, low fetal growth was associated with increased risk of IHD (HR for <-2 vs -1 to <1 SD, 1.54; 95% CI 1.15 to 2.07; p=0.004) and increased risk of MI (HR for <-2 vs -1 to <1 SD, 2.48; 95% CI 1.66 to 3.71; p<0.001) in young adulthood. In contrast, gestational age at birth was not associated with the risk of IHD or MI.

CONCLUSIONS

In this large national cohort, low fetal growth was strongly associated with IHD and MI in young adulthood, independently of gestational age at birth, sociodemographic factors, comorbidities and family history of IHD.

Copeptin is an independent predictor of diabetic heart disease and death

BACKGROUND

We previously discovered that high copeptin is associated with incidence of diabetes mellitus (diabetes), abdominal obesity, and albuminuria. Furthermore, copeptin predicts cardiovascular events after myocardial infarction in diabetic patients, but whether it is associated with heart disease and death in individuals without diabetes and prevalent cardiovascular disease is unknown. In this study, we aim to test whether plasma copeptin (copeptin), the C-terminal fragment of arginine vasopressin prohormone, predicts heart disease and death differentially in diabetic and nondiabetic individuals.

METHODS

We related plasma copeptin to a combined end point composed of coronary artery disease (CAD), heart failure (HF), and death in diabetes (n = 895) and nondiabetes (n = 4187) individuals of the Malmö Diet and Cancer Study-Cardiovascular cohort.

RESULTS

Copeptin significantly interacted with diabetes regarding the combined end point (P = .006). In diabetic individuals, copeptin predicted the combined end point (hazard ratio [HR] 1.32 per SD, 95% CI 1.10-1.58, P = .003) after adjustment for conventional risk factors, prevalent HF and CAD, and remained significant after additional adjustment for either fasting glucose (P = .02) or hemoglobin A1c (P = .02). Furthermore, in diabetic individuals, copeptin predicted CAD (HR 1.33 per SD, 95% CI 1.04-1.69, P = .02), HF (HR 1.62 per SD, 95% CI 1.09-2.41, P = .02), and death (HR 1.32 per SD, 95% CI 1.04-1.68, P = .02). Interestingly, among nondiabetic individuals, copeptin was not associated with any of the end points.

CONCLUSIONS

Copeptin predicted heart disease and death, specifically in diabetes patients, suggesting copeptin and the vasopressin system as a prognostic marker and therapeutic target for diabetic heart disease and death.

Association of postdischarge rehabilitation with mortality in intensive care unit survivors of sepsis

RATIONALE

Intensive care unit (ICU)-acquired weakness is a common issue for sepsis survivors that is characterized by impaired muscle strength and causes functional disability. Although inpatient rehabilitation has not been found to reduce in-hospital mortality, the impact of postdischarge rehabilitation on sepsis survivors is uncertain.

OBJECTIVES

To investigate the benefit of postdischarge rehabilitation to long-term mortality in sepsis survivors.

METHODS

We conducted a nationwide, population-based, high-dimensional propensity score-matched cohort study using Taiwan's National Health Insurance Research Database. The rehabilitation cohort comprised 15,535 ICU patients who survived sepsis and received rehabilitation within 3 months after discharge between 2000 and 2010. The control cohort consisted of 15,535 high-dimensional propensity score-matched subjects who did not receive rehabilitation within 3 months after discharge. The endpoint was mortality during the 10-year follow-up period.

MEASUREMENTS AND MAIN RESULTS

Compared with the control cohort, the rehabilitation cohort had a significantly lower risk of 10-year mortality (adjusted hazard ratio, 0.94; 95% confidence interval, 0.92-0.97; P < 0.001), with an absolute risk reduction of 1.4 per 100 person-years. The frequency of rehabilitation was inversely associated with 10-year mortality (≥3 vs. 1 course: adjusted hazard ratio, 0.82; P < 0.001). Compared with the control cohort, improved survival was observed in the rehabilitation cohort among ill patients who had more comorbidities, required more prolonged mechanical ventilation, and had longer ICU or hospital stays, but not among those with the opposite conditions (i.e., less ill patients).

CONCLUSIONS

Postdischarge rehabilitation may be associated with a reduced risk of 10-year mortality in the subset of patients with particularly long ICU courses.

Urinary calculi and risk of cancer: a nationwide population-based study

Previous studies have shown that urinary calculi are associated with increased risks of urinary tract cancers. However, the association between urinary calculi and overall cancers is a largely undefined body of knowledge. We conducted a nationwide population-based cohort study using Taiwan's National Health Insurance Research Database from 2000 and 2009. Patients were excluded if they had antecedent cancers or urinary calculi before the enrollment. All study subjects were followed until the occurrence of cancer, dropout from the NHI program, death, or the end of 2010. Patterns of cancer incidence in patients with urinary calculi were compared with those of the general population using standardized incidence ratio (SIR). A total of 43,516 patients with urinary calculi were included. After a median follow-up of 5.3 years, 1891 patients developed cancer. The risk of overall cancers was significantly increased (SIR, 1.75; 95% confidence interval [CI], 1.68-1.83). We observed that urinary calculi was associated with higher risk of cancers of kidney (4.24; 95% CI, 3.47-5.13), bladder (3.30; 95% CI, 2.69-4.00), thyroid (2.50; 95% CI, 1.78-3.40), hematologic origin (2.41; 95% CI, 1.92-2.99), breast (1.84; 95% CI, 1.54-2.20), lung (1.82; 95% CI, 1.59-2.07), digestive tract (1.69; 95% CI, 1.57-1.82), and head and neck (1.54; 95% CI, 1.32-1.79), respectively. Our study shows that urinary calculi are associated with higher risk of systemic cancers in addition to urinary tract cancers. Further study is required to validate this association.

Increased risk of urinary calculi in patients with migraine: a nationwide cohort study

OBJECTIVE

Whether migraine is associated with urinary calculi is an unresolved issue, although topiramate, a migraine-preventive agent, is known to contribute to this complication. This study investigates the association between migraine and the risk of urinary calculi.

METHODS

We identified a total of 147,399 patients aged ≥18 years with migraine diagnoses recorded in the Taiwan National Health Insurance Research Database between 2005 and 2009. Each patient was randomly matched with one individual without headache using propensity scores. All participants were followed from the date of enrollment until urinary calculi development, death, or the end of 2010.

RESULTS

The risk of urinary calculi was greater in the migraine than the control cohort (adjusted hazard ratio (aHR), 1.58; 95% confidence interval (CI), 1.52-1.63; p < 0.001, irrespective of the influence of topiramate. The risk was higher in younger and female patients. The magnitude of the risk was proportional to the annual frequency of clinic visits for headache (≥6 vs. <3, aHR = 1.11; 95% CI, 1.04-1.17; p = 0.002), but did not differ between migraine patients with and without aura.

CONCLUSIONS

Our study showed migraine was associated with an increased risk of urinary calculi, independent of topiramate use. A higher frequency of clinic visits was associated with a greater risk.

Proton pump inhibitor use represents an independent risk factor for myocardial infarction

BACKGROUND

There is substantial debate regarding the development of acute coronary syndrome in patients using proton pump inhibitors (PPIs) combined with clopidogrel. However, data remain limited to address the effect of PPIs alone on the subsequent risk of myocardial infarction (MI). We aimed to explore the subsequent risk of MI in PPI users who had no previous history of MI.

METHODS

The records of inpatients and outpatients with PPI prescriptions were retrieved from the Taiwan National Health Insurance Research Database between 2000 and 2009. We conducted two different study designs, the first using propensity score (PS)-matching analyses and the second using case-crossover analyses. The risk of developing MI for PPI users was analyzed in the PS-matched study. The association between risk of MI and prior PPI exposure was further validated in the case-crossover study.

RESULTS

In the PS-matched study, we included 126,367 PPI users and 126,367 PS-matched PPI non-users. After 120 days of follow-up, PPI use was associated with a 1.58-fold greater risk of MI (adjusted hazard ratio [HR] = 1.58, 95% confidence interval [CI] = 1.11 to 2.25). In the case-crossover study, adjusted odds ratios of PPI for MI risk were 4.61 (95% CI = 1.76 to 12.07) for the 7-day window and 3.47 (95% CI = 1.76 to 6.83) for the 14-day window.

CONCLUSIONS

Use of PPIs may be independently associated with an increased risk of MI. However, the benefits of PPIs may greatly outweigh the risks of adverse cardiovascular effects, with number needed to harm of 4357.

Cataract surgery is associated with a reduced risk of dementia: a nationwide population-based cohort study

BACKGROUND AND PURPOSE

Our purpose was to determine the association of cataract surgery with subsequent development of dementia in older adults with newly diagnosed cataract.

METHODS

By using data from Taiwan National Health Insurance Research Database (NHIRD), a population-based cohort study including 491 226 subjects aged 70 or older with first-time diagnosis of cataract coded from 2000 to 2009 was conducted. After matching cataract patients receiving cataract surgery with cataract patients without receiving cataract surgery for age, sex, index date, Charlson Comorbidity Index score, interval between first coding of cataract diagnosis and index date, hypertension and diabetes mellitus, 113 123 patients in each cohort were enrolled. The main outcome measure was newly diagnosed dementia coded by neurologists or psychiatrists more than 365 days after cataract surgery. Incidence rate and hazard ratio of dementia were compared between the cataract surgery and cataract diagnosis cohorts.

RESULTS

The incidence rate of dementia was 22.40 per 1000 person-years in the cataract surgery cohort and 28.87 per 1000 person-years in the cataract diagnosis cohort. The rate of dementia was significantly lower in the cataract surgery group (hazard ratio 0.77, 95% confidence interval 0.75-0.79, P < 0.001). Female gender (P < 0.001) and a shorter interval between the date of first coding of a cataract diagnosis and the date of cataract surgery (P = 0.009) were significantly associated with a lower incidence rate of dementia.

CONCLUSION

In an NHIRD cohort of Taiwanese aged 70 years and older with a diagnosis of cataract, patients undergoing cataract surgery were associated with a reduced risk of subsequent dementia compared with those without cataract surgery.

Venous thromboembolism and varicose veins share familial susceptibility: a nationwide family study in Sweden

Background

Varicose veins (VVs) have been associated with venous thromboembolism (VTE), but whether these diseases share familial susceptibility has not been determined. This nationwide study aimed to determine whether VTE shares familial susceptibility with VVs.

Methods and Results

Swedish Multigeneration Register data for persons aged 0 to 76 years during the period 1964–2008 were linked to the Swedish Inpatient and Outpatient Registers. Familial risks (standardized incidence ratios [SIRs]) of VTE and VVs were examined in 2 ways (ie, bidirectionally): risk of VTE in subjects whose siblings had been diagnosed with VVs and risk of VVs in persons whose siblings had been diagnosed with VTE. The analyses were repeated for spouses to determine the importance of shared adult family environment. In total, 96 810 siblings had VVs and 87 564 had VTE. An increased risk of VTE was observed in persons whose siblings had VVs (SIR 1.30, 95% CI 1.26 to 1.33), whereas persons whose siblings had VTE had an increased risk of VVs (SIR 1.30, 95% CI 1.27 to 1.34). If 2 or more siblings were affected by VTE, the risk for VVs was 1.70 (95% CI 1.53 to 1.88). Conversely, if 2 or more siblings were affected by VVs, the risk for VTE was 1.52 (95% CI 1.38 to 1.67). In spouses of VTE patients, a minor increased risk of VVs was observed (SIR 1.05 for husbands, SIR 1.06 for wives). The risk of VTE in spouses of VV patients was similarly small (SIR 1.01 for husbands, SIR 1.05 for wives).

Conclusions

VVs and VTE share familial susceptibility. This novel finding suggests the existence of shared familial and possibly genetic factors.

Risk of tuberculosis among healthcare workers in an intermediate-burden country: a nationwide population study

OBJECTIVE

The potential association between healthcare workers (HCWs) and the risk of clinically active tuberculosis (TB) in countries with intermediate TB burdens remains unclear.

METHODS

A nationwide, population-based cohort study was performed by using Taiwan National Health Insurance Database during 2000-2010. We included HCWs and non-HCWs without history of tuberculosis matched at a 1:1 ratio according to age, sex, monthly income, underlying comorbidities, and concomitant medications. All subjects were followed from the date of enrollment until TB occurrence, death, or 31 December 2010.

RESULTS

The study population comprised 11,811 healthcare workers and 11,811 matched subjects. 62 HCWs and 38 control subjects developed TB during a median follow-up period of 9.4 years. The incidence of TB was higher among HCWs than among matched subjects (61.08 vs. 37.81 per 100,000 person-years). The risk of TB was also greater among HCWs (adjusted hazard ratio [aHR], 1.62; 95% confidence interval [CI], 1.08-2.43), particularly for pulmonary TB in comparison with extrapulmonary TB (aHR, 1.56; 95% CI, 1.02-2.39). Among different job categories of HCWs, we found that only nurses had a significantly increased risk of developing TB (aHR, 2.55; 95% CI, 1.37-4.72) compared to the matched cohort.

CONCLUSIONS

HCWs are associated independently with a higher risk of developing TB in this intermediate-burden country. Therefore, the importance of TB surveillance among HCWs should be emphasized.

Pyogenic liver abscess in end-stage renal disease patients: a nationwide longitudinal study

End-stage renal disease (ESRD) patients are more prone to infectious disease because of their immunocompromised status. However, the association between pyogenic liver abscess (PLA) and ESRD remains not clear. The aim of our study is to evaluate the incidence, risk factors, and outcomes of PLA in ESRD patients. We recruited all incident ESRD patients from the Taiwan National Health Insurance database from 1998 to 2006. The incidence rate of PLA in ESRD patients was compared with that of a randomly selected non-ESRD control group matched for age, sex gender, Charlson comorbidity score, diabetes mellitus, and cirrhosis. Among the 57,761 incident dialysis patients, there were 538 cases of PLA. The incidence rate of PLA was 18.20 per 10,000 person-years in the ESRD cohort and 6.34 per 10,000 person-years in matched control cohort. The rate of PLA was significantly higher in the ESRD cohort (hazard ratio 3.63, 95% confidence interval 2.83-4.65, P < 0.001). The mortality rates of PLA were higher in the ESRD cohort than those in matched control cohort. Diabetes mellitus was an independent risk factor for mortality of PLA. Compared with non-ESRD patients, ESRD patients have a higher risk of PLA and poorer outcomes.

Genetic factors may play a prominent role in the development of coronary heart disease dependent on important environmental factors

OBJECTIVE

The aim of the study was to examine whether various lifestyle factors modify genetic influences on coronary heart disease (CHD).

DESIGN

The effect of lifestyle factors [including smoking, sedentary lifestyle, alcohol intake and body mass index (BMI)] on risk of CHD was evaluated via Cox regression models in a twin study of gene-environment interaction. Using structure equation modelling, we estimated genetic variance of CHD dependent on lifestyle factors.

SUBJECTS

In total, 51 065 same-sex twins from 25 715 twin pairs born before 1958 and registered in the Swedish Twin Registry were eligible for this study. During the 40-year follow-up, 7264 incident CHD events were recorded.

RESULTS

Smoking, sedentary lifestyle and above average BMI were significantly associated with increased CHD incidence. The heritability of CHD decreased with increasing age, as well as with increasing levels of BMI, in both men and women.

CONCLUSIONS

The difference in the genetic component of CHD as a function of BMI suggests that genetic factors may play a more prominent role for disease development in the absence of important environmental factors. Increased knowledge of gene-environment interactions will be important for a full understanding of the aetiology of CHD.

Validity of myocardial infarction diagnoses in administrative databases: a systematic review

BACKGROUND

Though administrative databases are increasingly being used for research related to myocardial infarction (MI), the validity of MI diagnoses in these databases has never been synthesized on a large scale.

OBJECTIVE

To conduct the first systematic review of studies reporting on the validity of diagnostic codes for identifying MI in administrative data.

METHODS

MEDLINE and EMBASE were searched (inception to November 2010) for studies: (a) Using administrative data to identify MI; or (b) Evaluating the validity of MI codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value, or Kappa scores) for MI, or data sufficient for their calculation. Additonal articles were located by handsearch (up to February 2011) of original papers. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

Thirty studies published from 1984-2010 were included; most assessed codes from the International Classification of Diseases (ICD)-9th revision. Sensitivity and specificity of hospitalization data for identifying MI in most [≥50%] studies was ≥86%, and PPV in most studies was ≥93%. The PPV was higher in the more-recent studies, and lower when criteria that do not incorporate cardiac troponin levels (such as the MONICA) were employed as the gold standard. MI as a cause-of-death on death certificates also demonstrated lower accuracy, with maximum PPV of 60% (for definite MI).

CONCLUSIONS

Hospitalization data has higher validity and hence can be used to identify MI, but the accuracy of MI as a cause-of-death on death certificates is suboptimal, and more studies are needed on the validity of ICD-10 codes. When using administrative data for research purposes, authors should recognize these factors and avoid using vital statistics data if hospitalization data is not available to confirm deaths from MI.

Suicide, fatal injuries, and other causes of premature mortality in patients with traumatic brain injury: a 41-year Swedish population study

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IMPORTANCE

Longer-term mortality in individuals who have survived a traumatic brain injury (TBI) is not known.

OBJECTIVES

To examine the relationship between TBI and premature mortality, particularly by external causes, and determine the role of psychiatric comorbidity.

DESIGN, SETTING, AND PATIENTS

We studied all persons born in 1954 or later in Sweden who received inpatient and outpatient International Classification of Diseases-based diagnoses of TBI from 1969 to 2009 (n = 218,300). We compared mortality rates 6 months or more after TBI to general population controls matched on age and sex (n = 2,163,190) and to unaffected siblings of patients with TBI (n = 150,513). Furthermore, we specifically examined external causes of death (suicide, injury, or assault). We conducted sensitivity analyses to investigate whether mortality rates differed by sex, age at death, severity (including concussion), and different follow-up times after diagnosis.

MAIN OUTCOMES AND MEASURES

Adjusted odds ratios (AORs) of premature death by external causes in patients with TBI compared with general population controls.

RESULTS

Among those who survived 6 months after TBI, we found a 3-fold increased odds of mortality (AOR, 3.2; 95% CI, 3.0-3.4) compared with general population controls and an adjusted increased odds of mortality of 2.6 (95% CI, 2.3-2.8) compared with unaffected siblings. Risks of mortality from external causes were elevated, including for suicide (AOR, 3.3; 95% CI, 2.9-3.7), injuries (AOR, 4.3; 95% CI, 3.8-4.8), and assault (AOR, 3.9; 95% CI, 2.7-5.7). Among those with TBI, absolute rates of death were high in those with any psychiatric or substance abuse comorbidity (3.8% died prematurely) and those with solely substance abuse (6.2%) compared with those without comorbidity (0.5%).

CONCLUSIONS AND RELEVANCE

Traumatic brain injury is associated with substantially elevated risks of premature mortality, particularly for suicide, injuries, and assaults, even after adjustment for sociodemographic and familial factors. Current clinical guidelines may need revision to reduce mortality risks beyond the first few months after injury and address high rates of psychiatric comorbidity and substance abuse.

Registration of acute stroke: validity in the Danish Stroke Registry and the Danish National Registry of Patients

BACKGROUND

The validity of the registration of patients in stroke-specific registries has seldom been investigated, nor compared with administrative hospital discharge registries. The objective of this study was to examine the validity of the registration of patients in a stroke-specific registry (The Danish Stroke Registry [DSR]) and a hospital discharge registry (The Danish National Patient Registry [DNRP]).

METHODS

Assuming that all patients with stroke were registered in either the DSR, DNRP or both, we first identified a sample of 75 patients registered with stroke in 2009; 25 patients in the DSR, 25 patients in the DNRP, and 25 patients registered in both data sources. Using the medical record as a gold standard, we then estimated the sensitivity and positive predictive value of a stroke diagnosis in the DSR and the DNRP. Secondly, we reviewed 160 medical records for all potential stroke patients discharged from four major neurologic wards within a 7-day period in 2010, and estimated the sensitivity, specificity, positive predictive value, and negative predictive value of the DSR and the DNRP.

RESULTS

Using the first approach, we found a sensitivity of 97% (worst/best case scenario 92%-99%) in the DSR and 79% (worst/best case scenario 73%-84%) in the DNRP. The positive predictive value was 90% (worst/best case scenario 72%-98%) in the DSR and 79% (worst/best case scenario 62%-88%) in the DNRP. Using the second approach, we found a sensitivity of 91% (95% confidence interval [CI] 81%-96%) and 58% (95% CI 46%-69%) in the DSR and DNRP, respectively. The negative predictive value was 91% (95% CI 83%-96%) in the DSR and 72% (95% CI 62%-80%) in the DNRP. The specificity and positive predictive value did not differ among the registries.

CONCLUSION

Our data suggest a higher sensitivity in the DSR than the DNRP for acute stroke diagnoses, whereas the positive predictive value was comparable in the two data sources.

Premature mortality in epilepsy and the role of psychiatric comorbidity: a total population study

BACKGROUND

Epilepsy is associated with high rates of premature mortality, but the contribution of psychiatric comorbidity is uncertain. We assessed the prevalence and risks of premature mortality from external causes such as suicide, accidents, and assaults in people with epilepsy with and without psychiatric comorbidity.

METHODS

We studied all individuals born in Sweden between 1954 and 2009 with inpatient and outpatient diagnoses of epilepsy (n=69,995) for risks and causes of premature mortality. Patients were compared with age-matched and sex-matched general population controls (n=660,869) and unaffected siblings (n=81,396). Sensitivity analyses were done to investigate whether these odds differed by sex, age, seizure types, comorbid psychiatric diagnosis, and different time periods after epilepsy diagnosis.

RESULTS

6155 (8.8%) people with epilepsy died during follow-up, at a median age of 34·5 (IQR 21·0-44·0) years with substantially elevated odds of premature mortality (adjusted odds ratio [aOR] of 11·1 [95% CI 10·6-11·6] compared with general population controls, and 11·4 [10·4-12·5] compared with unaffected siblings). Of those deaths, 15·8% (n=972) were from external causes, with high odds for non-vehicle accidents (aOR 5·5, 95 % CI 4·7-6·5) and suicide (3·7, 3·3-4·2). Of those who died from external causes, 75·2% had comorbid psychiatric disorders, with strong associations in individuals with co-occurring depression (13·0, 10·3-16·6) and substance misuse (22·4, 18·3-27·3), compared with patients with no epilepsy and no psychiatric comorbidity.

INTERPRETATION

Reducing premature mortality from external causes of death should be a priority in epilepsy management. Psychiatric comorbidity plays an important part in the premature mortality seen in epilepsy. The ability of health services and public health measures to prevent such deaths requires review.

FUNDING

Wellcome Trust, the Swedish Prison and Probation Service, and the Swedish Research Council.

The epidemiology of heart failure, based on data for 2.1 million inhabitants in Sweden

AIMS

The epidemiology of congestive heart failure (CHF) is likely to have changed due to changes in demography, risk factors, diagnostic procedures, and medical care. Prevailing information is in part old, incomplete, and to some extent contradictory. We determined the current prevalence, incidence, mortality, and 5-year survival rate of CHF, and possible temporal changes in Sweden.

METHODS AND RESULTS

This was a cross-sectional study on individual patient data from an administrative health data register in the Stockholm region, Sweden, comprising 2.1 million inhabitants. This contained all recorded diagnoses on all consultations in primary and secondary care (defined as specialist outpatient care), and on all hospitalizations. Prevalence, incidence, and mortality were estimated for the entire Swedish population, adjusted for demographic composition in 2010. The study population consisted of 88 038 patients (51% women). The prevalence was 2.2% (both women and men), the incidence was 3.8/1000 person-years (both women and men), and mortality was 3.2/1000 person-years in women and 3.0/1000 person-years in men (P < 0.001); the 5-year survival rate was 48%. Mortality (age adjusted; hazard ratio and 95% confidence intervals) was higher in men, 1.29, 1.24-1.34; P < 0.001. Prevalence remained essentially unchanged from 2006 to 2010, while incidence decreased by 24% (P < 0.001) and mortality by 19% (both women and men; P < 0.001).

CONCLUSIONS

The estimated prevalence of CHF in Sweden is 2.2%, incidence 3.8/1000 person-years, and mortality 3.1/1000 person-years. There has been a decrease in incidence and mortality from 2006 to 2010 in both women and men, with no major change in prevalence over time.

Genetic variants from lipid-related pathways and risk for incident myocardial infarction

BACKGROUND

Circulating lipids levels, as well as several familial lipid metabolism disorders, are strongly associated with initiation and progression of atherosclerosis and incidence of myocardial infarction (MI).

OBJECTIVES

We hypothesized that genetic variants associated with circulating lipid levels would also be associated with MI incidence, and have tested this in three independent samples.

SETTING AND SUBJECTS

Using age- and sex-adjusted additive genetic models, we analyzed 554 single nucleotide polymorphisms (SNPs) in 41 candidate gene regions proposed to be involved in lipid-related pathways potentially predisposing to incidence of MI in 2,602 participants of the Swedish Twin Register (STR; 57% women). All associations with nominal P<0.01 were further investigated in the Uppsala Longitudinal Study of Adult Men (ULSAM; N = 1,142).

RESULTS

In the present study, we report associations of lipid-related SNPs with incident MI in two community-based longitudinal studies with in silico replication in a meta-analysis of genome-wide association studies. Overall, there were 9 SNPs in STR with nominal P-value <0.01 that were successfully genotyped in ULSAM. rs4149313 located in ABCA1 was associated with MI incidence in both longitudinal study samples with nominal significance (hazard ratio, 1.36 and 1.40; P-value, 0.004 and 0.015 in STR and ULSAM, respectively). In silico replication supported the association of rs4149313 with coronary artery disease in an independent meta-analysis including 173,975 individuals of European descent from the CARDIoGRAMplusC4D consortium (odds ratio, 1.03; P-value, 0.048).

CONCLUSIONS

rs4149313 is one of the few amino acid changing variants in ABCA1 known to associate with reduced cholesterol efflux. Our results are suggestive of a weak association between this variant and the development of atherosclerosis and MI.

Renal dysfunction increases the risk of ischemic and hemorrhagic stroke in the general population

AIMS

The association between chronic kidney disease (CKD) and different subtypes of stroke is unclear, and previous studies have yielded conflicting results. We aimed to assess the impact of CKD on the risk of fatal or non-fatal ischemic and hemorrhagic stroke in both men and women.

METHODS

In 539,287 Swedish men and women, mainly undergoing health controls, with mean age 45 years, and no previous stroke or myocardial infarction, hazard ratios for stroke were calculated to assess the association between renal dysfunction and incidence of stroke. We estimated glomerular filtration rates (GFR) using the Mayo (GFR-Mayo) formula. Glomerular filtration rate 60-90, 30-60, and 15-30 mL per minute per 1.73 m(2) was defined as mildly, moderately, and severely decreased GFR, respectively.

RESULTS

There were 17,678 strokes, of which 72% were ischemic, 15% hemorrhagic, and 12% unspecified, during 12 years of follow-up. Hazard ratios (95% confidence intervals) for ischemic stroke were 1.09 (1.04-1.14) for mildly, 1.24 (1.10-1.39) for moderately, and 2.27 (1.63-3.17) for severely decreased GFR-Mayo. The corresponding figures for hemorrhagic stroke were 1.04 (0.93-1.15), 1.26 (0.96-1.64), and 2.31 (1.10-4.87). Ischemic stroke was related to all levels of decreased GFR-Mayo in both genders (P < 0.0003). Hemorrhagic stroke was only related to renal dysfunction among women; hazard ratios (95% confidence intervals) 1.38 (1.14-1.66) for mildly, 1.70 (1.13-2.57) for moderately, and 3.46 (1.09-10.9) for severely decreased GFR-Mayo.

CONCLUSIONS

Already mildly decreased GFR-Mayo increases the risk of ischemic fatal or non-fatal stroke and severely decreased GFR-Mayo the risk of hemorrhagic stroke in the general population. In gender-specific analyses ischemic stroke was related to a decreased GFR-Mayo in both genders. Hemorrhagic stroke was only related to renal dysfunction among women.

Case definitions for acute myocardial infarction in administrative databases and their impact on in-hospital mortality rates

OBJECTIVE

To identify validated ICD-9-CM/ICD-10 coded case definitions for acute myocardial infarction (AMI).

DATA SOURCES

Ovid Medline (1950-2010) was searched to identify studies that validated acute myocardial infarction (AMI) case definitions. Hospital discharge abstract data and chart data were linked to validate identified AMI definitions.

STUDY DESIGN

Systematic literature review, chart review, and administrative data analysis.

DATA COLLECTION/EXTRACTION METHODS

Data on sensitivity/specificity/positive and negative predictive values (PPV and NPV) were extracted from previous studies to identify validated case definitions for AMI. These case definitions were validated in administrative data through chart review and applied to hospital discharge data to assess in-hospital mortality.

PRINCIPAL FINDINGS

Of the eight ICD-9-CM definitions validated in the literature, use of ICD-9-CM code 410 to define AMI had the highest sensitivity (94 percent) and specificity (99 percent). In our data, ICD-9-CM/ICD-10 codes 410/I21-I22 in all available coding fields had high sensitivity (83.3 percent/82.8 percent) and PPV (82.8 percent/82.2 percent). The in-hospital mortality among AMI patients identified using this case definition was 7.6 percent in ICD-9-CM data and 6.6 percent in ICD-10 data.

CONCLUSIONS

We recommend that ICD-9-CM 410 or ICD-10 I21-I22 in the primary diagnosis coding field should be used to define AMI. The use of a consistent validated case definition would improve comparability across studies.

Risk of subsequent ischemic and hemorrhagic stroke in patients hospitalized for immune-mediated diseases: a nationwide follow-up study from Sweden

Background

Certain immune-mediated diseases (IMDs) have been associated with increased risk for cardiovascular disorders. The aim of the present study was to examine whether there is an association between 32 different IMDs and first hospitalization for ischemic or hemorrhagic stroke.

Methods

All individuals in Sweden hospitalized with a main diagnosis of IMD (without previous or coexisting stroke), between January 1, 1987 and December 31, 2008 (n = 216,291), were followed for first hospitalization for ischemic or hemorrhagic stroke. The reference population was the total population of Sweden. Adjusted standardized incidence ratios (SIRs) for ischemic and hemorrhagic stroke were calculated.

Results

Totally 20 and 15 of the 32 IMDs studied, respectively, were associated with an increased risk of ischemic and hemorrhagic stroke during the follow-up. The overall risks of ischemic and hemorrhagic stroke during the first year after hospitalization for IMD were 2.02 (95% CI 1.90–2.14) and 2.65 (95% CI 2.27–3.08), respectively. The overall risk of ischemic or hemorrhagic stroke decreased over time, to 1.50 (95% CI 1.46–1.55) and 1.83 (95% CI 1.69–1.98), respectively, after 1–5 years, and 1.29 (95% CI 1.23–1.35) and 1.47 (95% CI 1.31–1.65), respectively, after 10+ years. The risk of hemorrhagic stroke was ≥2 during the first year after hospitalization for seven IMDs: ankylosing spondylitis (SIR = 8.11), immune thrombocytopenic purpura (SIR = 8.60), polymyalgia rheumatica (SIR = 2.06), psoriasis (SIR = 2.88), rheumatoid arthritis (SIR = 3.27), systemic lupus erythematosus (SIR = 8.65), and Wegener´s granulomatosis (SIR = 5.83). The risk of ischemic stroke was ≥2 during the first year after hospitalization for twelve IMDs: Addison’s disease (SIR = 2.71), Crohn´s disease (SIR = 2.15), Grave´s disease (SIR = 2.15), Hashimoto´s thyroiditis (SIR = 2.99), immune thrombocytopenic purpura (SIR = 2.35), multiple sclerosis (SIR = 3.05), polymyositis/dermatomyositis (SIR = 3.46), rheumatic fever (SIR = 3.91), rheumatoid arthritis (SIR = 2.08), Sjögren’s syndrome (SIR = 2.57), systemic lupus erythematosus (SIR = 2.21), and ulcerative colitis (SIR = 2.15).

Conclusions

Hospitalization for many IMDs is associated with increased risk of ischemic or hemorrhagic stroke. The findings suggest that several IMDs are linked to cerebrovascular disease.

Cohort Profile: the National Prostate Cancer Register of Sweden and Prostate Cancer data Base Sweden 2.0

In 1987, the first Regional Prostate Cancer Register was set up in the South-East health-care region of Sweden. Other health-care regions joined and since 1998 virtually all prostate cancer (PCa) cases are registered in the National Prostate Cancer Register (NPCR) of Sweden to provide data for quality assurance, bench marking and clinical research. NPCR includes data on tumour stage, Gleason score, serum level of prostate-specific antigen (PSA) and primary treatment. In 2008, the NPCR was linked to a number of other population-based registers by use of the personal identity number. This database named Prostate Cancer data Base Sweden (PCBaSe) has now been extended with more cases, longer follow-up and a selection of two control series of men free of PCa at the time of sampling, as well as information on brothers of men diagnosed with PCa, resulting in PCBaSe 2.0. This extension allows for studies with case-control, cohort or longitudinal case-only design on aetiological factors, pharmaceutical prescriptions and assessment of long-term outcomes. The NPCR covers >96% of all incident PCa cases registered by the Swedish Cancer Register, which has an underreporting of <3.7%. The NPCR is used to assess trends in incidence, treatment and outcome of men with PCa. Since the national registers linked to PCBaSe are complete, studies from PCBaSe 2.0 are truly population based.