Considerations for the use of biochemical laboratory registry data in clinical and public health research

OBJECTIVES

To inform researchers of central considerations and limitations when applying biochemical laboratory-generated registry data in clinical and public health research.

STUDY DESIGN AND SETTING

After review of literature on registry-based studies and the utilization of clinical laboratory registry data, relevant paragraphs and their applicability toward the creation of considerations for the use of biochemical registry data in research were evaluated. This led to the creation of an initial ten considerations. These were elaborated, edited, and merged after several read-throughs by all authors and discussed thoroughly under influence by the authors' personal experiences with laboratory databases and research registries in Denmark, leading to the formulation of five central considerations with corresponding items and illustrative examples.

RESULTS

We recommend that the following considerations should be addressed in studies relying on biochemical laboratory-generated registry data: why are biochemical laboratory data relevant to examine the hypothesis, and how were the variable(s) utilized in the study? What were the primary indications for specimen collection in the study population of interest? Were there any pre-analytical circumstances that could influence the test results? Are data comparable between producing laboratories and within the single laboratory over time? Is the database representative in terms of completeness of study populations and key variables?

CONCLUSION

It is crucial to address key errors in laboratory registry data and acknowledge potential limitations.

Risk and adverse clinical outcomes of thrombocytopenia among patients with solid tumors-a Danish population-based cohort study

BACKGROUND

Knowledge about thrombocytopenia among patients with solid tumors is scarce. We examined the risk of thrombocytopenia among patients with solid tumors and its association with adverse outcomes.

METHODS

Using Danish health registries, we identified all patients with incident solid tumors from 2015-2018 (n = 52,380) and a platelet count measurement within 2 weeks prior to or on their cancer diagnosis date. The risk of thrombocytopenia was categorized as grades 0 (any platelet count × 109/L): <150; 1: <100; 2: <75; 3: <50; 4: <25, and 5: <10. To study the outcomes, each patient with thrombocytopenia was matched with up to five cancer patients without thrombocytopenia by age, sex, cancer type, and stage. Cox regression was used to compute hazard ratios (HRs) of bleeding, transfusion, or death, adjusting for confounding factors.

RESULTS

The 1-year risk of thrombocytopenia was 23%, increasing to 30% at 4 years. This risk was higher in patients receiving chemotherapy (43% at 1 year and 49% at 4 years). Overall, patients with thrombocytopenia had higher 30-days rates of bleeding (HR = 1.72 [95% confidence interval, CI: 1.41-2.11]). Thrombocytopenia was also associated with an increased rate of transfusion, and death, but some of the risk estimates were imprecise.

CONCLUSIONS

The risk of thrombocytopenia was substantial among patients with solid tumors and associated with adverse outcomes.

Oral anticoagulant treatment and risk of kidney disease-a nationwide, population-based cohort study

Background

Direct oral anticoagulants (DOACs) are recommended as first-line treatment of atrial fibrillation. Whether DOAC use is associated with lower risks of kidney complications compared with vitamin K antagonists (VKAs) remains unclear. We examined this association in a nationwide, population-based cohort study.

Methods

We conducted a cohort study including patients initiating oral anticoagulant treatment within 3 months after an atrial fibrillation diagnosis in Denmark during 2012-18. Using routinely collected creatinine measurements from laboratory databases, we followed patients in an intention-to-treat approach for acute kidney injury (AKI) and chronic kidney disease (CKD) progression. We used propensity-score weighting to balance baseline confounders, computed weighted risks and weighted hazard ratios (HRs) with 95% confidence intervals (CIs) comparing DOACs with VKAs. We performed several subgroup analyses and a per-protocol analysis.

Results

We included 32 781 persons with atrial fibrillation initiating oral anticoagulation (77% initiating DOACs). The median age was 75 years, 25% had a baseline estimated glomerular filtration rate <60 mL/min/1.73 m2, and median follow-up was 2.3 (interquartile range 1.1-3.9) years. The weighted 1-year risks of AKI were 13.6% in DOAC users and 15.0% in VKA users (HR 0.86, 95% CI 0.82; 0.91). The weighted 5-year risks of CKD progression were 13.9% in DOAC users and 15.4% in VKA users (HR 0.85, 95% CI 0.79; 0.92). Results were similar across subgroups and in the per-protocol analysis.

Conclusions

Initiation of DOACs was associated with a decreased risk of AKI and CKD progression compared with VKAs. Despite the potential limitations of observational studies, our findings support the need for increased clinical awareness to prevent kidney complications among patients who initiate oral anticoagulants.

High-intensity versus moderate-intensity statin treatment for patients with ischemic stroke: Nationwide cohort study

PURPOSE

Guidelines recommend high-intensity statin treatment after ischemic stroke, but evidence is sparse on the effectiveness and safety of different statin treatment intensities. We examined effectiveness and safety outcomes among patients initiating high-intensity versus moderate-intensity statins after ischemic stroke.

METHODS

In this population-based new-user active-comparator cohort study, we used the Danish Stroke Registry, covering all Danish hospitals, to identify patients with a first-time ischemic stroke during 2012-2021. Using multiple Danish registries, patients who redeemed a statin prescription within 21 days after stroke admission were classified as high-intensity statin initiators or moderate-intensity statin initiators. Propensity score inverse probability of treatment weighting was used to balance patient characteristics. We used competing risk methods to compute 5 year risk differences (RDs) and Cox proportional hazards regression to compute 5 year hazard ratios (HRs) of stroke recurrence, myocardial infarction, heart failure, venous thromboembolism, and all-cause mortality (effectiveness outcomes) and diabetes, liver disease, and kidney disease (safety outcomes).

RESULTS

High-intensity (n = 13,032) and moderate-intensity (n = 14,355) statin initiators were identified. Risks of most examined effectiveness outcomes were comparable between statin intensities. There was no clear association between statin intensity and stroke recurrence (RD: 0.8% [95% CI: 0.1, 1.4], HR: 1.08 [95% CI: 0.96, 1.22]). All-cause mortality was slightly reduced among high-intensity statin initiators (RD: -1.1% [95% CI: -0.1, -2.1], HR: 0.93 [95% CI: 0.85, 1.01]. Risks of most safety outcomes were comparable between statin intensities, but high-intensity statin use was associated with an increased risk of diabetes (RD: 1.2% [95% CI: 0.4, 1.9], HR: 1.10 [95% CI: 1.00, 1.21]).

DISCUSSION AND CONCLUSION

Compared with initiation of moderate-intensity statins, initiation of high-intensity statins after ischemic stroke was associated with similar risks of most effectiveness and safety outcomes. However, mortality risk was reduced, and diabetes risk was increased.

Risk and Prognosis of Cancer in Patients With Cerebral Venous Thrombosis Compared With the Danish General Population

BACKGROUND

Whether cerebral venous thrombosis (CVT) is a marker of cancer in clinical practice remains unknown. Little is known about the prognosis of cancer detected subsequent to CVT.

METHODS

We used Danish nationwide registries (1996-2019) to identify patients with a first-time primary inpatient diagnosis of CVT without a history of cancer (N=811, 65% women, median age 42 years). We assessed the risk of an incident cancer diagnosis using standardized incidence ratios (SIRs). This measure contrasts the number of observed cancers among patients with CVT to the number of expected cancers where patients with CVT have the same cancer risk as the general population. We used Kaplan-Meier survival analysis and Cox regression to compare the survival of patients with both cancer and CVT with the survival of patients with cancer but without CVT, matched on cancer site, sex, age, and year of cancer diagnosis.

RESULTS

Observing 43 incident cancer cases during follow-up, the overall SIR was unity (SIR, 1.04 [95% CI, 0.75-1.40]). However, the risk was ≈7-fold the expected level in the first 3 months following CVT diagnosis (SIR, 7.00 [95% CI, 3.02-13.80]) and ≈2-fold the expected level from 3 to 12 months following CVT diagnosis (SIR, 2.21 [95% CI, 0.89-4.56]). By 12 months following CVT diagnosis, the risk resembled the expected level (SIR, 0.76 [95% CI, 0.50-1.09]). Survival among cancer patients with prior CVT versus cancer patients without prior CVT was 91% versus 87% after 6 months and 65% versus 70% after 5 years. The adjusted hazard ratio of death was 0.78 (95% CI, 0.44-1.38).

CONCLUSIONS

Patients with CVT were not at overall increased risk of a cancer diagnosis, except in the first 3 months after diagnosis during which period the risk was elevated ≈7-fold. The estimate from this early period, however, was based on only a few cancer diagnoses. Unlike other forms of venous thrombosis, a prior diagnosis of CVT did not negatively impact cancer survival.

Preadmission Opioid Use and 1-Year Mortality Following Incident Myocardial Infarction: A Danish Population-Based Cohort Study (1997-2016)

Background Opioid use has been linked to an increased risk of myocardial infarction and cardiovascular mortality, but the prognostic impact of opioid use before an incident myocardial infarction is largely unknown. Methods and Results We conducted a nationwide population-based cohort study including all patients hospitalized for an incident myocardial infarction in Denmark (1997-2016). Based on their last redeemed opioid prescription before admission, patients were categorized as current users (0-30 days), recent users (31-365 days), former users (>365 days), and nonusers. One-year all-cause mortality was calculated using the Kaplan-Meier method. Hazard ratios (HRs) were computed using Cox proportional hazards regression analyses, adjusting for age, sex, comorbidity, any preceding surgery within 6 months before the myocardial infarction admission, and medication use before the myocardial infarction admission. We identified 162 861 patients with an incident myocardial infarction. Of these, 8% were current opioid users, 10% were recent opioid users, 24% were former opioid users, and 58% were nonusers of opioids. One-year mortality was highest among current users (42.5% [95% CI, 41.7%-43.3%]) and lowest among nonusers (20.5% [95% CI, 20.2%-20.7%]). Compared with nonusers, current users had an elevated 1-year all-cause mortality risk (adjusted HR, 1.26 [95% CI, 1.22-1.30]). Following adjustment, neither recent users nor former users of opioids were at elevated risk. Conclusions Preadmission opioid use was associated with an increased 1-year all-cause mortality risk following an incident myocardial infarction. Opioid users thus represent a high-risk subgroup of patients with myocardial infarction.

In vitro Effect of Dalteparin and Argatroban on Hemostasis in Critically Ill Sepsis Patients with New-Onset Thrombocytopenia

Thrombocytopenia is common among critically ill sepsis patients, while they also hold an increased risk for thromboembolic events. Thus, the choice of anticoagulant prophylaxis for this patient population is challenging. We investigated the in vitro effect of low-molecular-weight heparin (dalteparin) and direct thrombin inhibitor (argatroban) on the hemostasis in blood from sepsis patients with new-onset thrombocytopenia. Thrombocytopenia was defined as a platelet count drop of ≥30% and/or from >100 × 10 ⁹ /L to 30 to 100 × 10 ⁹ /L within 24 hours prior to inclusion. We included five healthy individuals and ten patients. Analyses of thrombin generation (Calibrated Automated Thrombogram), thrombin-antithrombin (TAT) complex levels, prothrombin fragment 1+2 (F1+2), and rotational thromboelastometry (ROTEM) were performed. Based on dose-response relationships investigated in healthy blood, patient samples were spiked with prophylactic (0.25 IU/mL) and therapeutic (0.75 IU/mL) dalteparin and low (0.25 µg/mL) and high (0.50 µg/mL) argatroban concentrations, each with a sample without anticoagulant. In patients, the endogenous thrombin potential was markedly lower in therapeutic dalteparin samples than in samples without anticoagulant [median (range): 29 (0-388) vs. 795 (98-2121) nM × min]. In high argatroban concentration samples, thrombin lag time was longer than in samples without anticoagulant [median (range): 15.5 (10.5-20.2) versus 5.3 (2.8-7.3) min]. Dalteparin and argatroban both increased clotting time but did not affect maximum clot firmness in the ROTEM INTEM assay. Six patients had elevated TAT and eight patients had elevated F1 + 2. In conclusion, dalteparin mainly affected the amount of thrombin generated and argatroban delayed clot initiation in critically ill sepsis patients with new-onset thrombocytopenia. Neither anticoagulant affected clot strength.

Labour market participation and retirement after stroke in Denmark: registry based cohort study

OBJECTIVE

To examine labour market participation and retirement among patients with stroke and matched people in the general population according to stroke subtype.

DESIGN

Nationwide, population based, matched cohort study.

SETTING

Danish Stroke Registry, covering all Danish hospitals, and other nationwide registries (2005-18).

PARTICIPANTS

Patients (aged 18-60 years and active in the labour market) with a first time diagnosis of ischaemic stroke (n=16 577), intracerebral haemorrhage (n=2025), or subarachnoid haemorrhage (n=4305), and individuals from the general population, matched on age, sex, and calendar year (n=134 428). The median Scandinavian stroke scale score was 55.

MAIN OUTCOME MEASURES

Unweighted prevalences of labour market participation, receipt of sick leave benefits, receipt of disability pension, voluntary early retirement, state pension, and death were computed for each week and up to five years after stroke diagnosis. A log-linear Poisson model was used to obtain exact prevalence estimates as well as propensity score weighted prevalence differences and prevalence ratios at six months, one year, two years, and five years after stroke diagnosis.

RESULTS

Most patients (62% of those with ischaemic stroke, 69% of those with intracerebral haemorrhage, and 52% of those with subarachnoid haemorrhage) went on sick leave within three weeks of diagnosis. Prevalence of labour market participation among patients with ischaemic stroke compared with matched individuals from the general population was 56.6% versus 96.6% at six months, and 63.9% versus 91.6% at two years. Prevalence of sick leave was 39.8% versus 2.6% at six months, and 15.8% versus 3.8% at two years. Prevalence of receipt of a disability pension was 0.9% versus 0.2% at six months, and 12.2% versus 0.6% at two years. Adjusting for socioeconomic and comorbidity differences between patients and matched individuals from the general population using propensity score weighting methods had little impact on contrasts. Patients with intracerebral haemorrhage had higher prevalences of sick leave and receipt of a disability pension and thus a lower prevalence of labour market participation, while prevalences for patients with subarachnoid haemorrhage were similar in magnitude to those for patients with ischaemic stroke.

CONCLUSIONS

In a highly resourced country, about two thirds of working age adults with ischaemic stroke of primarily mild severity participated in the labour market two years after diagnosis. Sick leave and receipt of a disability pension were the most common reasons for non-participation. Patients with intracerebral haemorrhage were less likely to return to the labour market than patients with ischaemic stroke and subarachnoid haemorrhage.

Exploring the epidemiology of disseminated intravascular coagulation: protocol for the DANish Disseminated Intravascular Coagulation (DANDIC) Cohort Study

INTRODUCTION

Since disseminated intravascular coagulation (DIC) was first described, it has been considered a serious disease of the coagulation system and a major challenge to clinicians. Currently, several important knowledge gaps remain. The DANish Disseminated Intravascular Coagulation (DANDIC) Cohort Study will aim to answer questions regarding the incidence and mortality of patients with DIC including time trends. The study will also identify prognostic factors that may guide personalised prevention and treatment. Furthermore, the study will describe treatment patterns and the safety and effectiveness of various treatment modalities.

METHODS AND ANALYSIS

We will establish the DANDIC Cohort using data collected in daily clinical practice from the Central Denmark Region, which covers approximately 1.3 million residents. The study period will encompass 1 January 2011 through 1 July 2021. Potential DIC cases will be identified from the hospital laboratory database, based on coagulation biomarkers, and diagnoses will be adjudicated by medical experts. The dataset will be enriched with detailed clinical data from electronic medical charts on aetiologies, bleeding, microthrombus formation, organ failure, thrombosis, treatments and comorbidities. The dataset will also take advantage of in-hospital data with longitudinal information on laboratory records, transfusions, microbiology and treatments. It will be possible to merge this dataset with other unique Danish health registries with more than 10 years of virtually complete follow-up. The project will use state-of-the-art epidemiological and biostatistical methods.

ETHICS AND DISSEMINATION

The project has been approved by the Danish Patient Safety Authority (31-1521-452), the Central Denmark Region (1-45-70-83-21), the Danish Data Protection Agency (1-16-02-258-21) and all the hospital chairs. Register-based studies require no ethical approval in Denmark. The results will be disseminated in international peer-reviewed journals.

Evaluation of Neurologic and Psychiatric Outcomes After Hospital Discharge Among Adult Survivors of Cardiac Arrest

IMPORTANCE

Long-term risks of neurologic and psychiatric disease after cardiac arrest are largely unknown.

OBJECTIVE

To examine the short-term and long-term risks of common neurologic outcomes (stroke, epilepsy, Parkinson disease, and dementia) and psychiatric outcomes (depression and anxiety) in patients after hospitalization for cardiac arrest.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide population-based cohort study with 21 years of follow-up included data on 250 838 adults from all Danish hospitals between January 1, 1996, and December 31, 2016. Danish medical registries were used to identify all patients with a first-time diagnosis of cardiac arrest and 2 matched comparison cohorts. The first comparison cohort included patients with a first-time diagnosis of myocardial infarction; the second comprised people from the general population. Data analysis was performed from November 1, 2020, to June 30, 2021.

EXPOSURES

In-hospital or out-of-hospital cardiac arrest.

MAIN OUTCOMES AND MEASURES

Neurologic and psychiatric outcomes after hospital discharge were ascertained using medical registries. Twenty-one-year hazard ratios (HRs) and 95% CIs were computed based on Cox regression analysis, controlled for matching factors, and adjusted for comorbidity and socioeconomic status.

RESULTS

Among the 250 838 individuals included in this study (median age, 67 years [IQR, 57-76 years]; 173 946 [69.3%] male), 3 groups were identified: 12 046 patients with cardiac arrest, 118 332 patients with myocardial infarction, and 120 460 people from the general population. Compared with patients with myocardial infarction, patients with cardiac arrest had an increased rate of ischemic stroke (10 per 1000 persons; HR, 1.30; 95% CI, 1.02-1.64) and hemorrhagic stroke (2 per 1000 persons; HR, 2.03; 95% CI, 1.12-3.67) in the first year after discharge. During the full follow-up period, rates were as follows: for epilepsy, 28 per 1000 persons (HR, 2.01; 95% CI, 1.66-2.44); for dementia, 73 per 1000 persons (HR, 1.23; 95% CI, 1.09-1.38); for mood disorders including depression, 270 per 1000 persons (HR, 1.78; 95% CI, 1.68-1.89); and for anxiety, 187 per 1000 persons (HR, 1.98; 95% CI, 1.85-2.12). The rate of Parkinson disease was similar in the 2 cohorts (8 per 1000 persons; HR, 0.96; 95% CI, 0.65-1.42). The rates of the aforementioned outcomes were highest during the first year after cardiac arrest and then declined over time. Comparisons between the cohort of patients with cardiac arrest and the general population cohort showed higher rates of epilepsy, dementia, depression, and anxiety in the cardiac arrest group.

CONCLUSIONS AND RELEVANCE

In this cohort study, patients discharged after cardiac arrest had an increased rate of subsequent stroke, epilepsy, dementia, depression, and anxiety compared with patients with myocardial infarction and people from the general population, with declining rates over time. These findings suggest the need for preventive strategies and close follow-up of cardiac arrest survivors.

Stroke and Risk of Mental Disorders Compared With Matched General Population and Myocardial Infarction Comparators

BACKGROUND

Accurate estimates of risks of poststroke outcomes from large population-based studies can provide a basis for public health policy decisions. We examined the absolute and relative risks of a spectrum of incident mental disorders following ischemic stroke and intracerebral hemorrhage.

METHODS

During 2004 to 2018, we used Danish registries to identify patients (≥18 years and with no hospital history of mental disorders), with a first-time ischemic stroke (n=76767) or intracerebral hemorrhage (n=9344), as well as age-,sex-, and calendar year-matched general population (n=464 840) and myocardial infarction (n=92 968) comparators. We computed risk differences, considering death a competing event, and hazard ratios adjusted for income, occupation, education, and history of cardiovascular and noncardiovascular comorbidity.

RESULTS

Compared with the general population, following ischemic stroke, the 1-year risk difference was 7.3% (95% CI, 7.0-7.5) for mood disorders (driven by depression), 1.4% (95% CI, 1.3-1.5) for organic brain disorders (driven by dementia and delirium), 0.8% (95% CI, 0.7-0.8) for substance abuse disorders (driven by alcohol and tobacco abuse), and 0.5% (95% CI, 0.4-0.5) for neurotic disorders (driven by anxiety and stress disorders). For suicide, risk differences were near null. Hazard ratios were particularly elevated in the first year of follow-up, ranging from a 2- to a 4-fold increased hazard, decreasing thereafter. Compared with myocardial infarction patients, the 1-year risk difference was 4.9% (95% CI, 4.6 to 5.3) for mood disorders, 1.0% (95% CI, 0.8 to 1.1) for organic brain disorders, 0.1% (95% CI, 0.0 to 0.2) for substance abuse disorders, but -0.2% (95% CI, -0.2 to -0.1) for neurotic disorders. Hazard ratios during the first year of follow-up were elevated 1.1- to 1.8-fold for mood, organic brain, and neurotic disorders, while decreased 0.8-fold for neurotic disorders.

CONCLUSIONS

The considerably greater risks of mental disorders following a stroke, particularly mood disorders, underline the importance of mental health evaluation after stroke.

Atrial fibrillation, liver cirrhosis, thrombosis, and bleeding: A Danish population‐based cohort study

Objectives

We examined the impact of liver cirrhosis on the risk of thromboembolic events and bleeding complications in patients with atrial fibrillation or flutter (AFF).

Methods

This population‐based cohort study used data from Danish health registries. We identified all patients with a first‐time diagnosis of AFF during 1995 to 2015, and followed them from their AFF diagnosis until the end of 2016. Patients were categorized according to the presence or absence of liver cirrhosis. We computed incidence rates per 1000 person‐years and hazard ratios (HRs) with 95% confidence intervals (CIs) based on Cox regression analyses, adjusting for age, CHA₂DS₂VASc score, and Charlson Comorbidity Index score.

Results

We identified 273 225 patients with AFF. Of these, 1463 (0.54%) had liver cirrhosis. During 0 to 5 years of follow‐up, compared to patients without liver cirrhosis, patients with liver cirrhosis had higher incidence rates and hazards of ischemic stroke (29.7 vs 21.6; HR, 1.3; 95% CI, 1.1‐1.6), venous thromboembolism (9.2 vs 5.5; HR, 1.5; 95% CI, 1.2‐2.3), but not myocardial infarction (10.2 vs 11.2; HR, 0.9; 95% CI, 0.7–1.2). Patients with liver cirrhosis also had higher rates of hemorrhagic stroke (5.8 vs 3.3; HR, 1.7; 95% CI, 1.1‐2.6), subdural hemorrhage (5.3 vs 1.6; HR, 3.2; 95% CI, 2.1‐4.9), hemorrhage of the lung or urinary tract (24.6 vs 15.2; HR, 1.6; 95% CI, 1.3–2.0), and gastrointestinal hemorrhage (34.5 vs 10.4; HR, 3.3; 95% CI, 2.7–3.9).

Conclusion

In patients with AFF, liver cirrhosis was associated with an elevated risk of ischemic stroke, venous thromboembolism, and all evaluated bleeding complications.

Risk of Parkinson Disease and Secondary Parkinsonism in Myocardial Infarction Survivors

Background

In addition to primary neurodegenerative processes, vascular disorders, such as stroke, can lead to parkinsonism. However, some cardiovascular risk factors, such as smoking and elevated cholesterol levels, are associated with reduced risk of Parkinson disease. We examined the risk of Parkinson disease and secondary parkinsonism in 1‐year survivors of myocardial infarction (MI).

Methods and Results

We conducted a nationwide population‐based matched cohort study using Danish medical registries from 1995 to 2016. We identified all patients with a first‐time MI diagnosis and sampled a sex‐, age‐, and calendar year–matched general population comparison cohort without MI. Cox regression analysis was used to compute adjusted hazard ratios (aHRs) for Parkinson disease and secondary parkinsonism, controlled for matching factors and adjusted for relevant comorbidities and socioeconomic factors. We identified 181 994 patients with MI and 909 970 matched comparison cohort members (median age, 71 years; 62% men). After 21 years of follow‐up, the cumulative incidence was 0.9% for Parkinson disease and 0.1% for secondary parkinsonism in the MI cohort. Compared with the general population cohort, MI was associated with a decreased risk of Parkinson disease (aHR, 0.80; 95% CI, 0.73–0.87) and secondary parkinsonism (aHR, 0.72; 95% CI, 0.54–0.94).

Conclusions

MI was associated with a 20% decreased risk of Parkinson disease and 28% decreased risk of secondary parkinsonism. Reduced risk may reflect an inverse relationship between cardiovascular risk factors and Parkinson disease.

Risks of Stroke Recurrence and Mortality After First and Recurrent Strokes in Denmark: A Nationwide Registry Study

BACKGROUND AND OBJECTIVES

To examine risks of stroke recurrence and mortality after first and recurrent stroke.

METHODS

Using Danish nationwide health registries, we included patients age ≥18 years with first-time ischemic stroke (n = 105,397) or intracerebral hemorrhage (ICH) (n = 13,350) from 2004 to 2018. Accounting for the competing risk of death, absolute risks of stroke recurrence were computed separately for each stroke subtype and within strata of age groups, sex, stroke severity, body mass index, smoking, alcohol use, Essen stroke risk score, and atrial fibrillation. Mortality risks were computed after first and recurrent stroke.

RESULTS

After adjusting for competing risks, the overall 1-year and 10-year risks of recurrence were 4% and 13% following first-time ischemic stroke and 3% and 12% following first-time ICH. For ischemic stroke, the risk of recurrence increased with age and was higher for men and following mild vs more severe stroke. The most marked differences were across Essen risk scores, for which recurrence risks increased with increasing scores. For ICH, risks were similar for both sexes and did not increase with Essen risk score. For ischemic stroke, the 1-year and 10-year risks of all-cause mortality were 17% and 56% after a first-time stroke and 25% and 70% after a recurrent stroke; corresponding estimates for ICH were 37% and 70% after a first-time event and 31% and 75% after a recurrent event.

DISCUSSION

The risk of stroke recurrence was substantial following both subtypes, but risks differed markedly among patient subgroups. The risk of mortality was higher after a recurrent than first-time stroke.

Biotin interference in routine IDS-iSYS immunoassays for aldosterone, renin, insulin-like growth factor 1, growth hormone and bone alkaline phosphatase

Biotin is increasingly used as dietary supplement. As many immunoassays rely on a binding between biotin and streptavidin, intake of biotin may interfere with laboratory tests, leading to spurious test results. We examined the extent to which levels of aldosterone, renin, insulin-like growth factor 1 (IGF-1), growth hormone (GH) and bone alkaline phosphatase (BAP) were affected by biotin. In an experimental study performed at Aarhus University Hospital, Denmark, patient samples (plasma or serum) were pooled and spiked with biotin in increasing concentrations (0, 20, 50, 100 and 500 ng/mL). All biomarkers were analyzed using Immunodiagnostic Systems (IDS-iSYS) Multi-Discipline Automated System assays. The average bias (%) was calculated, as the difference in concentrations between the sample without biotin (reference) and the samples with increasing concentrations of biotin. Both aldosterone and renin assays showed substantial biotin interference in a dose-dependent manner, with biases up to +3484% for aldosterone and -98% for renin in the highest concentrations of biotin (100-500 ng/mL). IGF-1, GH and BAP results were generally less affected by added biotin and significant bias (>10%) was observed only when the biotin concentration was 100 ng/mL (IGF-1 and GH) or 500 ng/mL (BAP). In conclusion, biotin interfered with the IDS-iSYS immunoassays, particularly for aldosterone and renin. The assays for GH, IGF-1 and BAP were less sensitive and only with high concentrations of biotin.

Disseminated intravascular coagulation diagnosis: Positive predictive value of the ISTH score in a Danish population

BACKGROUND

The diagnostic accuracy of the ISTH's disseminated intravascular coagulation (DIC) score remains to be investigated in contemporary patient populations.

OBJECTIVE

To examine the positive predictive value (PPV) of an ISTH DIC score ≥5 for identifying patients with overt DIC in a Danish hospital laboratory information system database.

MATERIALS AND METHODS

A population-based cross-sectional validation study in the Central Denmark Region (2015-2018). Patients with a DIC score ≥5 were identified from the hospital laboratory information system database. Only patients with a potential underlying cause of DIC were included in the analyses. Cases were adjudicated by the authors as the gold standard for DIC diagnosis. The diagnosis of overt DIC was assigned on the basis of clinical signs of microthrombosis and/or bleeding and available laboratory records. PPVs with 95% confidence intervals (CIs) were computed.

RESULTS

Medical records of 225 patients were included. The overall PPV for overt DIC was 68% (95% CI, 61-74) and for overt + subclinical DIC, 83% (95% CI, 77%-88%) and increased with higher scores from 47% (95% CI, 35-59) for DIC score 5 to 88 (95% CI, 79-94) for DIC score ≥7. PPV was higher among intensive care patients and patient with sepsis, low antithrombin activity, prolonged activated partial thromboplastin time, or high Sequential Organ Failure Assessment score.

CONCLUSION

The accuracy of ISTH DIC score ≥5 was moderate for overt DIC but increased with increasing scores and depended on the underlying cause of DIC. This new knowledge provides guidance to physicians and enables DIC research using laboratory-based data.

Dynamic Hemostasis and Fibrinolysis Assays in Intensive Care COVID-19 Patients and Association with Thrombosis and Bleeding-A Systematic Review and a Cohort Study

Patients admitted to the intensive care unit (ICU) with coronavirus disease 2019 (COVID-19), the infectious pathology caused by severe acute respiratory syndrome coronavirus 2, have a high risk of thrombosis, though the precise mechanisms behind this remain unclarified. A systematic literature search in PubMed and EMBASE identified 18 prospective studies applying dynamic coagulation assays in ICU COVID-19 patients. Overall, these studies revealed normal or slightly reduced primary hemostasis, prolonged clot initiation, but increased clot firmness. Thrombin generation assay parameters generally were equivalent to the control groups or within reference range. Fibrinolysis assays showed increased clot resistance. Only six studies related their findings to clinical outcome. We also prospectively included 51 COVID-19 patients admitted to the ICU. Blood samples were examined on day 1, 3-4, and 7-8 with platelet function tests, rotational thromboelastometry (ROTEM), in vivo and ex vivo thrombin generation, and clot lysis assay. Data on thrombosis, bleeding, and mortality were recorded during 30 days. Primary hemostasis was comparable to healthy controls, but COVID-19 patients had longer ROTEM-clotting times and higher maximum clot firmness than healthy controls. Ex vivo thrombin generation was similar to that of healthy controls while in vivo thrombin generation markers, thrombin-antithrombin (TAT) complex, and prothrombin fragment 1 + 2 (F1 + 2) were higher in ICU COVID-19 patients than in healthy controls. Impaired fibrinolysis was present at all time points. TAT complex and F1 + 2 levels were significantly higher in patients developing thrombosis (n = 16) than in those without. In conclusion, only few previous studies employed dynamic hemostasis assays in COVID-19 ICU-patients and failed to reveal a clear association with development of thrombosis. In ICU COVID-19 patients, we confirmed normal platelet aggregation, while in vivo thrombin generation was increased and fibrinolysis decreased. Thrombosis may be driven by increased thrombin formation in vivo.

Risk of primary gastrointestinal cancers following incident non-metastatic breast cancer: a Danish population-based cohort study

Objective

We examined the risk of primary gastrointestinal cancers in women with breast cancer and compared this risk with that of the general population.

Design

Using population-based Danish registries, we conducted a cohort study of women with incident non-metastatic breast cancer (1990–2017). We computed cumulative cancer incidences and standardised incidence ratios (SIRs).

Results

Among 84 972 patients with breast cancer, we observed 2340 gastrointestinal cancers. After 20 years of follow-up, the cumulative incidence of gastrointestinal cancers was 4%, driven mainly by colon cancers. Only risk of stomach cancer was continually increased beyond 1 year following breast cancer. The SIR for colon cancer was neutral during 2–5 years of follow-up and approximately 1.2-fold increased thereafter. For cancer of the oesophagus, the SIR was increased only during 6–10 years. There was a weak association with pancreas cancer beyond 10 years. Between 1990–2006 and 2007–2017, the 1–10 years SIR estimate decreased and reached unity for upper gastrointestinal cancers (oesophagus, stomach, and small intestine). For lower gastrointestinal cancers (colon, rectum, and anal canal), the SIR estimate was increased only after 2007. No temporal effects were observed for the remaining gastrointestinal cancers. Treatment effects were negligible.

Conclusion

Breast cancer survivors were at increased risk of oesophagus and stomach cancer, but only before 2007. The risk of colon cancer was increased, but only after 2007.

The Danish Myelodysplastic Syndromes Database: Patient Characteristics and Validity of Data Records

Background

The Danish Myelodysplastic Syndromes Database (DMDSD) comprises nearly all patients diagnosed with myelodysplastic syndromes (MDS) in Denmark since 2010. The DMDSD has not yet been used for epidemiological research and the quality of registered variables remains to be investigated.

Objective

To describe characteristics of the patients registered in the DMDSD and to calculate predictive values and the proportion of missing values of registered data records.

Methods

We performed a nationwide cross-sectional validation study of recorded disease and treatment data on MDS patients during 2010-2019. Patient characteristics and the proportion of missing values were tabulated. A random sample of 12% was drawn to calculate predictive values with 95% confidence intervals (CIs) of 48 variables using information from medical records as a reference standard.

Results

Overall, 2284 patients were identified (median age: 76 years, men 62%). Of these, 10% had therapy-related MDS, and 6% had an antecedent hematological disease. Hemoglobin level was less than 6.2 mmol/L for 59% of patients. Within the first two years of treatment, 59% received transfusions, 35% received erythropoiesis-stimulating agents, and 15% were treated with a hypomethylating agent. For the majority of variables (around 80%), there were no missing data. A total of 260 medical records were available for validation. The positive predictive value of the MDS diagnosis was 92% (95% CI: 88-95). Predictive values ranged from 64% to 100% and exceeded 90% for 36 out of 48 variables. Stratification by year of diagnosis suggested that the positive predictive value of the MDS diagnosis improved from 88% before 2015 to 95% after.

Conclusion

In this study, there was a high accuracy of recorded data and a low proportion of missing data. Thus, the DMDSD serves as a valuable data source for future epidemiological studies on MDS.

Cardiovascular events in cancer patients with bone metastases-A Danish population-based cohort study of 23,113 patients

INTRODUCTION

The incidence of cardiovascular events among cancer patients with bone metastases is poorly understood. We examined rates of cardiovascular events among cancer patients with bone metastases and mortality following such events.

METHODS

Using Danish health registries, we identified all Danish cancer patients diagnosed with bone metastases (1994-2013) and followed them from bone metastasis diagnosis. We computed incidence rates (IR) per 100 person-years and cumulative incidence for first-time inpatient hospitalization or outpatient clinic visit for cardiovascular events, defined as myocardial infarction, ischemic stroke, or venous thromboembolism (VTE). We also analyzed all-cause mortality rates including cardiovascular events as time-varying exposure with adjustment for age, sex, and Charlson Comorbidity Index score. All analyses were performed overall and stratified by cancer type (prostate, breast, lung, and other).

RESULTS

We included 23,113 cancer patients with bone metastases. The cumulative incidence of cardiovascular events was 1.3% at 30 days, 3.7% at 1 year, and 5.2% at 5 years of follow-up. The highest IR was observed for VTE, followed by ischemic stroke and myocardial infarction, both overall and by cancer types. Lung cancer patients with bone metastases had the highest incidence of cardiovascular events followed by prostate and breast cancer. Occurrence of any cardiovascular event was a strong predictor of death (5 years following the event, the adjusted hazard ratio was 1.8 [95% confidence interval: 1.7-1.9]).

CONCLUSION

Cancer patients with bone metastases had a substantial risk of developing cardiovascular events, and these events were associated with a subsequent increased mortality. Our findings underscore the importance of continuous optimized prevention of and care for cardiovascular disease among cancer patients with bone metastases.

Nationwide Trends in Incidence and Mortality of Stroke Among Younger and Older Adults in Denmark

OBJECTIVE

To investigate the extent to which the incidence and mortality of a first-time stroke among younger and older adults changed from 2005 to 2018 in Denmark using nationwide registries.

METHODS

We used the Danish Stroke Registry and the Danish National Patient Registry to identify patients 18 to 49 years of age (younger adults) and those ≥50 years of age (older adults) with a first-time ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage. We computed age-standardized incidence rates and 30-day and 1-year mortality risks separately for younger and older adults and according to smaller age groups, stroke subtype, sex, and severity (Scandinavian Stroke Scale score). Average annual percentage changes (AAPCs) were computed to assess temporal trends.

RESULTS

We identified 8,680 younger adults and 105,240 older adults with an ischemic stroke or intracerebral hemorrhage. The incidence rate per 100,000 person-years of ischemic stroke (20.8 in 2005 and 21.9 in 2018, AAPC -0.6 [95% confidence interval (CI) -1.5 to 0.3]) and intracerebral hemorrhage (2.2 in 2005 and 2.5 in 2018, AAPC 0.6 [95% CI -1.0 to 2.3]) remained steady in younger adults. In older adults, rates of ischemic stroke and intracerebral hemorrhage declined, particularly in those ≥70 years of age. Rates of subarachnoid hemorrhage declined, but more so in younger than older adults. Stroke mortality declined over time in both age groups, attributable largely to declines in the mortality after severe strokes. Most trends were similar for men and women.

CONCLUSION

The incidence of ischemic stroke and intracerebral hemorrhage was steady in younger adults from 2005 to 2018, while it dropped in adults >70 years of age. Stroke mortality declined during this time.

Disseminated intravascular coagulation: epidemiology, biomarkers, and management

Disseminated intravascular coagulation (DIC) is a systemic activation of the coagulation system, which results in microvascular thrombosis and, simultaneously, potentially life-threatening haemorrhage attributed to consumption of platelets and coagulation factors. Underlying conditions, e.g. infection, cancer, or obstetrical complications are responsible for the initiation and propagation of the DIC process. This review provides insights into the epidemiology of DIC and the current understanding of its pathophysiology. It details the use of diagnostic biomarkers, current diagnostic recommendations from international medical societies, and it provides an overview of emerging diagnostic and prognostic biomarkers. Last, it provides guidance on management. It is concluded that timely and accurate diagnosis of DIC and its underlying condition is essential for the prognosis. Treatment should primarily focus on the underlying cause of DIC and supportive treatment should be individualised according to the underlying aetiology, patient's symptoms and laboratory records.

Immature Platelets and Risk of Cardiovascular Events among Patients with Ischemic Heart Disease: A Systematic Review

BACKGROUND

 Immature platelets are larger and may be more thrombogenic than mature platelets. This systematic review included studies on the association between mean platelet volume (MPV), immature platelet count (IPC), and immature platelet fraction (IPF) and the risk of major cardiovascular events (MACEs) in patients with acute coronary syndrome (ACS) or stable coronary artery disease (CAD).

METHODS

 The literature search included studies in PubMed, Embase, Web of Science, and Cochrane Library. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Effect estimates that included multivariate adjusted odds ratios, relative risks, or hazard ratios were extracted.

RESULTS

 Forty-two studies were identified. High MPV was positively associated with MACE in 20 of 26 studies of patients with ACS, four of five studies in patients with stable CAD, and in all six studies comprising a combined population with ACS and stable CAD. Using continuous models of MPV in patients with ACS, effect estimates varied from 0.90 (95% confidence interval [CI]: 0.95-1.03) to 1.66 (95% CI: 1.32-2.09). The strength of these associations was broadly similar among patients with stable CAD and in combined populations. Five studies investigated IPC or IPF as exposures and all reported positive associations with MACE among patients with ACS, stable CAD, or in combined populations.

CONCLUSION

 This review demonstrated clear evidence for positive associations between measures of immature platelets and subsequent risk of MACE in acute and stable ischemic heart disease patients.

Constipation and risk of cardiovascular diseases: a Danish population-based matched cohort study

OBJECTIVES

To assess the risks of myocardial infarction, stroke, peripheral artery disease, venous thromboembolism, atrial fibrillation or atrial flutter and heart failure in patients with constipation compared with a general population cohort.

DESIGN

Population-based matched cohort study.

SETTING

All Danish hospitals and hospital outpatient clinics from 2004 to 2013.

PARTICIPANTS

Patients with a constipation diagnosis matched on age, sex and calendar year to 10 individuals without constipation from the general population.

MAIN OUTCOMES MEASURES

Comorbidity-adjusted and medication-adjusted hazard ratios (aHRs) for cardiovascular outcomes based on Cox regression analysis.

RESULTS

83 239 patients with constipation were matched to 832 384 individuals without constipation. The median age at constipation diagnosis was 46.5% and 41% were men. Constipation was strongly associated with venous thromboembolism (aHR 2.04, 95% CI 1.89 to 2.20), especially splanchnic venous thrombosis (4.23, 95% CI 2.45 to 7.31). Constipation was also associated with arterial events, including myocardial infarction (1.24, 95% CI 1.14 to 1.35), ischaemic stroke (1.50, 95% CI 1.41 to 1.60), haemorrhagic stroke (1.46, 95% CI 1.26 to 1.69), peripheral artery disease (1.34, 95% CI 1.20 to 1.50), atrial fibrillation or atrial flutter (1.27, 95% CI 1.20 to 1.34) and heart failure (1.52, 95% CI 1.42 to 1.62). The associations were strongest during the first year after the constipation diagnosis and strengthened with an increased number of laxative prescriptions.

CONCLUSIONS

Constipation was associated with an increased risk of several cardiovascular diseases, in particular venous thromboembolism.

Risk of primary urological and genital cancers following incident breast cancer: a Danish population-based cohort study

PURPOSE

The prevalence of breast cancer survivors has increased due to dissemination of population-based mammographic screening and improved treatments. Recent changes in anti-hormonal therapies for breast cancer may have modified the risks of subsequent urological and genital cancers. We examine the risk of subsequent primary urological and genital cancers in patients with incident breast cancer compared with risks in the general population.

METHODS

Using population-based Danish medical registries, we identified a cohort of women with primary breast cancer (1990-2017). We followed them from one year after their breast cancer diagnosis until any subsequent urological or genital cancer diagnosis. We computed incidence rates and standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) as the observed number of cancers relative to the expected number based on national incidence rates (by sex, age, and calendar year).

RESULTS

Among 84,972 patients with breast cancer (median age 61 years), we observed 623 urological cancers and 1397 genital cancers during a median follow-up of 7.4 years. The incidence rate per 100,000 person-years was stable during follow-up (83 for urological cancers and 176 for genital cancers). The SIR was increased for ovarian cancer (1.37, 95% CI 1.23-1.52) and uterine cancer (1.37, 95% CI 1.25-1.50), but only during the pre-aromatase inhibitor era (before 2007). Moreover, the SIR of kidney cancer was increased (1.52, 95% CI 1.15-1.97), but only during 2007-2017. The SIR for urinary bladder cancer was marginally increased (1.15, 95% CI 1.04-1.28) with no temporal effects. No associations were observed for cervical cancer.

CONCLUSION

Breast cancer survivors had higher risks of uterine and ovarian cancer than expected, but only before 2007, and of kidney cancer, but only after 2007. The risk of urinary bladder cancer was moderately increased without temporal effects, and we observed no association with cervical cancer.

Comorbidity and risk of venous thromboembolism after hospitalization for first-time myocardial infarction: A population-based cohort study

BACKGROUND

Myocardial infarction (MI) is a risk factor for venous thromboembolism (VTE). Although comorbidities affect MI prognosis, it is unclear whether they affect VTE risk after MI.

OBJECTIVES

We examined the impact of comorbidity on VTE risk after MI.

METHODS

We used nationwide population-based registries to identify first-time hospitalizations for MI and subsequent occurrence of VTE in Denmark (1995-2013). We included a comparison cohort from the general population matched 5:1 with MI patients by sex, age, and comorbidities. We computed 30-day and 1- to 12-month cumulative risks, rates, and hazard ratios of VTE. We also assessed the interaction between MI and comorbidity, defined as excess VTE risk in patients with both MI and comorbidity, by computing interaction contrasts and attributable fractions relating to the interaction.

RESULTS

Thirty-day and 1- to 12-month VTE risks were 0.6% and 0.5% in the MI cohort (n = 160 338) and 0.03% and 0.3% in the comparison cohort (n = 792 384). The 30-day hazard ratio for VTE in the MI cohort was 23 (95% confidence interval, 20-27), which decreased during 1-year follow-up. Thirty days after MI, interactions between MI and comorbidity accounted for 16% and 39% of VTE rates in MI patients with low-to-moderate and high comorbidity, respectively. The interactions were driven primarily by hemiplegia and cancer.

CONCLUSIONS

Thirty-day VTE risk was substantially increased after MI compared with the general population. Although the absolute VTE risk was low, comorbidity substantially increased this risk, especially hemiplegia and cancer. VTE prophylaxis might be indicated in such high-risk patients but warrants further investigation.

Changes in Childhood Body-Mass Index and Risk of Venous Thromboembolism in Adulthood

Background Childhood weight trajectories may influence cardiometabolic traits and thereby the risk of venous thromboembolism ( VTE ) later in life. We examined whether overweight and changes in weight status during childhood were associated with risk of VTE in adulthood. Methods and Results We used Danish medical registries to conduct a population-based cohort study of Danish schoolchildren aged 7 to 13 years and born during 1930-1989. We calculated body-mass index ( BMI ) z-scores based on weight and height measurements. We estimated hazard ratios using Cox regressions to examine associations between changes in BMI z-scores from 7 to 13 years of age and the subsequent risk of VTE . Among 313 998 children, 5007 girls and 5397 boys were diagnosed with VTE as adults. Compared with children with a normal BMI (25th to 75th percentile category) at both ages, children with a BMI persistently above the 75th percentile had a 1.30- to 1.50-fold increased risk of VTE in adulthood. Children who experienced a BMI increase from the 25th to 75th or >75th to 90th percentile to a higher percentile category had a 1.35- to 1.70-fold increased risk of adulthood VTE . Children whose BMI percentile category decreased between 7 and 13 years of age had a VTE risk similar to that of children with a persistently normal BMI . Conclusions Risk of VTE in adulthood was higher in children with a persistently above-average BMI . Whereas weight gain from 7 to 13 years of age additionally increased VTE risk, remission from overweight by 13 years of age completely reverted the risk.

Association between lipid fractions and age of first myocardial infarction

OBJECTIVE

Dyslipidemia is a major cause of early coronary heart disease (CHD). Low-density-lipoprotein cholesterol (LDL-C), remnant cholesterol (remnant-C) and high-density lipoprotein cholesterol (HDL-C) have all been shown to be associated with risk of CHD. We aimed to compare the association of these lipid fractions with age at first myocardial infarction(MI). Design. Multicenter study of consecutive patients hospitalized with a first MI. Linear regression models were used to assess the independent association of LDL-C, remnant-C and HDL-C with age at first MI. Results. The study included 1744 patients. In univariate analyses, LDL-C, remnant-C, and HDL-C were all significantly associated with age at first MI. However, in multivariate analyses only LDL-C [-2.5 years (95%CI: -3.1 to -1.8) per 1 SD increase] and to a lesser extent remnant-C [-0.9 years (95% CI: -1.5 to -0.3)] continued to be associated with age of MI, while HDL-C [0.5 years (95%CI: -0.2 to 1.2)] was not. Conclusions. LDL-C is the lipid fraction strongest associated with younger age of presentation of first MI. These results support the importance of controlling and treating LDL-C in prevention of premature MI.

Existing Data Sources in Clinical Epidemiology: Laboratory Information System Databases in Denmark

Routine biomarker results from hospital laboratory information systems, covering hospitals and general practitioners, in Denmark are available to researchers through access to the regional Clinical Laboratory Information System Research Database at Aarhus University and the nationwide Register of Laboratory Results for Research. This review describes these two data sources. The laboratory databases have different geographical and temporal coverage. They both include individual-level biomarker results that are electronically transferred from laboratory information systems. The biomarker results can be linked to all other Danish registries at the individual level, using the unique identifier, the CPR number. The databases include variables such as the CPR number, date and time (hour and minute) of sampling, NPU code, and name of the biomarker, identification code for the laboratory and the requisitioner, the test result with the corresponding unit, and the lower and upper reference limits. Access to the two databases differs since they are hosted by two different institutions. Data cannot be transferred outside Denmark, and direct access is provided only to Danish institutions. It is concluded that access to data on routine biomarkers expands the detailed biological and clinical information available on patients in the Danish healthcare system. The full potential is enabled through linkage to other Danish healthcare registries.

Cohort profile: the Funen Diabetes Database-a population-based cohort of patients with diabetes in Denmark

PURPOSE

Detailed population-based data are essential to understanding the epidemiology of diabetes and its clinical course. This article describes the Funen Diabetes Database (FDDB). The purpose of the FDDB was to serve as a shared electronic medical record system for healthcare professionals treating patients with diabetes. The cohort can also be used for research.

PARTICIPANTS

The FDDB covers a geographical area of almost 500 000 Danish inhabitants. It currently includes 3691 patients with type 1 diabetes, 19 085 patients with type 2 diabetes, 292 patients with other types of diabetes and 5992 patients with an unknown type of diabetes. Patients have been continuously enrolled from general practitioners and endocrinology departments in the Funen area in Denmark since 2003. Patients undergo a clinical work-up at their first diabetes contact and during follow-up visits. The information collected includes type of diabetes contact, blood pressure, height, weight, lifestyle factors (smoking, exercise), laboratory records (eg, haemoglobin A1c and cholesterol levels), results from foot examinations (eg, pulse, cutaneous sensitivity and ankle brachial index), results from eye examinations (eg, degree of retinopathy assessed by retinal photo and eye examination), glucose-lowering drugs and diabetic complications.

FINDINGS TO DATE

The FDDB cohort was followed for a total of 212 234 person-years up to 2016. A cross-sectional study described the prevalence of diabetic retinopathy and its associated risk factors. The clinical outcomes of patients with type 1 diabetes, type 2 diabetes and latent autoimmune diabetes in adults have been assessed. Linkage to population-based medical registries with complete follow-up has enabled the collection of extensive continuous data on general practice contacts, diagnoses and procedures from hospital contacts, medication use and mortality.

FUTURE PLANS

The FDDB serves as a strong data resource that will be used in future studies of diabetes epidemiology with focus on occurrence, risk factors, treatment, complications and prognosis.

Syncope as a sign of occult cancers: a population-based cohort study

BACKGROUND

We examined if syncope was a marker of an occult cancer by comparing the risk in patients with a syncope episode with that of the general population.

METHODS

Using Danish population-based medical registries, we identified all patients diagnosed with syncope during 1994-2013 and followed them until a cancer diagnosis, emigration, death or end of follow-up, whichever came first. We computed cumulative risks and standardised incidence ratios (SIR) with 95% confidence intervals (CI).

RESULTS

Among 208,361 patients with syncope, 20,278 subsequent cancers were observed. The 6-month cumulative risk of any cancer was 1.2%, increasing to 17.9 % for 1-20 years of follow-up. The highest cumulative risks after 6 months of follow-up were lung cancer (0.2%), colorectal cancer (0.2%), prostate cancer (0.1%) and brain cancer (0.1%). The 6-month SIR were 2.7 (95% CI: 2.4-3.0) for lung cancer, 2.0 (95% CI: 1.8-2.2) for colorectal cancer, 1.7 (95% CI: 1.5-1.9) for prostate cancer and 10.0 (95% CI: 8.6-11.4) for brain cancer.

CONCLUSIONS

Syncope was a weak marker of an occult cancer. In short-term the highest cumulative risks were observed for lung, colorectal, prostate and brain cancers. An aggressive search for occult cancer in a patient with syncope is probably not warranted.

Effectiveness and safety of direct oral anticoagulants in atrial fibrillation patients switched from vitamin K antagonists: A systematic review and meta-analysis

A substantial proportion of atrial fibrillation patients initiating direct oral anticoagulants (DOAC) are vitamin K antagonists (VKA)-experienced, for example switchers from VKA to DOAC. With this study, we aimed to summarize available evidence on the effectiveness and safety of DOAC vs VKA in real-life VKA-experienced atrial fibrillation patients. We searched EMBASE, MEDLINE and Cochrane Library systematically for English-language studies indexed any time before October 2018. We included studies of VKA-experienced atrial fibrillation patients initiating DOAC therapy, with continued VKA therapy as comparator. Outcomes included arterial thromboembolism and bleeding. When appropriate, meta-analysis was performed by calculating pooled, weighted and adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Eight cohort studies comparing VKA-experienced DOAC (dabigatran or rivaroxaban) users with continued VKA users were included. When comparing DOAC to VKA, an increased risk of ischaemic stroke and myocardial infarction was found for dabigatran (pooled aHR of 1.61 [95% CI 1.19-2.19, I2  = 65%] and 1.29 [95% CI 1.10-1.52, I2  = 0%], respectively), but not for rivaroxaban. The use of dabigatran in VKA-experienced users was associated with an increased risk of gastrointestinal bleeding (pooled aHR 1.63 [95% CI 1.36-1.94, I2  = 30%]), but a decreased risk of intracranial bleeding (pooled aHR 0.45 [95% CI 0.32-0.64, I2  = 0%]). In conclusion, the use of dabigatran in prior VKA users in clinical practice was associated with a slightly increased risk of arterial thromboembolism and gastrointestinal bleeding, but a decreased risk of intracranial bleeding. Importantly, observational studies of real-life VKA-experienced oral anticoagulant users may be confounded by the reason for switching.

Elevated potassium levels in patients with chronic kidney disease: occurrence, risk factors and clinical outcomes-a Danish population-based cohort study

Background

Data on the true burden of hyperkalemia (HK) in patients with chronic kidney disease (CKD) in a real-world setting are scarce.

Methods

The incidence rate of HK [first blood test with an elevated blood potassium level level >5.0 mmol/L] in primary or hospital care was assessed in a population-based cohort of all newly diagnosed CKD patients [second estimated glomerular filtration rate (eGFR) measurement <60 mL/min/1.73 m2 or hospital diagnosis] in northern Denmark. Risk factors and clinical outcomes were compared for CKD patients with HK and matched CKD patients without HK.

Results

Of 157 766 patients with CKD, 28% experienced HK, for an overall HK incidence rate of 70/1000 person-years. Among patients with Stage 3A, 3B, 4 or 5 CKD, 9, 18, 31 and 42%, respectively, experienced HK within the first year. Important HK risk factors included diabetes {prevalence ratio [PR] 1.74 [95% confidence interval (CI) 1.69-1.79]}, heart failure [PR 2.31 (95% CI 2.23-2.40)] and use of angiotensin-converting enzyme inhibitors [PR 1.45 (95% CI 1.42-1.48)], potassium supplements [PR 1.59 (95% CI 1.55-1.62)] or spironolactone [PR 2.53 (95% CI 2.44-2.63)]. In CKD patients who developed HK, 34% had any acute hospitalization 6 months before the HK event, increasing to 57% 6 months after HK [before-after risk ratio 1.72 (95% CI 1.69-1.74)]. The 6-month mortality following HK was 26%, versus 6% in matched non-HK patients. Compared with non-HK patients, 6-month hazard ratios for any acute hospitalization in HK patients were 2.11-fold higher, including hazard ratios of 2.07 for cardiac diagnoses, 2.29 for ventricular arrhythmias, 3.26 for cardiac arrest, 4.77 for intensive care and 4.85 for death.

Conclusions

More than one in four CKD patients develops HK. Patients with severe CKD, diabetes, heart failure or use of spironolactone are at high risk. HK is associated with severe clinical outcomes.

Influence of Acetylsalicylic Acid Use on Risk and Outcome of Community-Acquired Staphylococcus aureus Bacteremia: A Population-Based Study

Objective

To investigate the influence of acetylsalicylic acid (ASA) use on risk and outcome of community-acquired Staphylococcus aureus bacteremia (CA-SAB).

Method

We used population-based medical databases to identify all patients diagnosed in northern Denmark with first-time CA-SAB and matched population controls from 2000–2011. Categories for ASA users included current users (new or long-term users), former users, and nonusers. The analyses were adjusted for comorbidities, comedication use, and socioeconomic indicators.

Results

We identified 2638 patients with first-time CA-SAB and 26 379 matched population controls. Compared with nonusers, the adjusted odds ratio (aOR) for CA-SAB was 1.00 (95% confidence interval [CI], 0.88–1.13) for current users, 1.00 (95% CI, 0.86–1.16) for former users, 2.04 (95% CI, 1.42–2.94) for new users, and 0.95 (95% CI, 0.84–1.09) for long-term users. Thirty-day cumulative mortality was 28.0% among current users compared with 21.6% among nonusers, yielding an adjusted hazard rate ratio (aHRR) of 1.02 (95% CI, 0.84–1.25). Compared with nonusers, the aHRR was 1.10 (95% CI, 0.87–1.40) for former users, 0.60 (95% CI, 0.29–1.21) for new users, and 1.06 (95% CI, 0.87–1.31) for long-term users. We observed no difference in the risk or outcome of CA-SAB with increasing ASA dose or by presence of diseases commonly treated with ASA.

Conclusions

Use of ASA did not seem to influence the risk or outcome of CA-SAB. The apparent increased risk among new users may relate to residual confounding from the circumstances underlying ASA treatment initiation. Our finding of no association remained robust with increasing ASA dose and across multiple patient subsets.

Risk and Prognosis of Cancer After Lower Limb Arterial Thrombosis

BACKGROUND

Venous thromboembolism can be a presenting symptom of cancer, but the association between lower limb arterial thrombosis and cancer is unknown. We therefore examined cancer risk and prognosis of cancer in patients with lower limb arterial thrombosis.

METHODS

Using nationwide population-based Danish medical registries, we identified all patients diagnosed with first-time lower limb arterial thrombosis (1994-2013) and followed them until the occurrence of any subsequent cancer diagnosis, emigration, death, or November 30, 2013, whichever came first. We computed standardized incidence ratios with 95% confidence intervals as the observed number of cancers relative to the expected number based on national incidence rates by sex, age, and calendar year. To examine the prognostic impact of lower limb arterial thrombosis on all-cause mortality after cancer, we constructed a matched comparison cohort of patients who had cancer without lower limb arterial thrombosis.

RESULTS

Among 6600 patients with lower limb arterial thrombosis, we observed 772 subsequent cancers. The risk of any cancer was 2.5% after 6 months of follow-up, increasing to 17.9% after 20 years. During the first 6 months of follow-up, the standardized incidence ratio of any cancer was 3.28 (95% confidence interval, 2.79-3.82). The standardized incidence ratio remained elevated during 7 to 12 months (1.42; 95% confidence interval, 1.09-1.83) and beyond 12 months (1.14; 95% confidence interval, 1.05-1.24). The strongest associations were found for lung cancer and other smoking-related cancers. Lower limb arterial thrombosis also was associated with increased all-cause mortality after colon, lung, urinary bladder, and breast cancer, but not after prostate cancer.

CONCLUSIONS

Lower limb arterial thrombosis was a marker of occult cancer, especially lung cancer, and was an adverse prognostic factor for mortality in common cancers.

Risk of cancer in patients with fecal incontinence

BACKGROUND

Fecal incontinence may be an early symptom of cancer, but its association with cancer remains unclear. We examined the risk of selected cancers, including colorectal cancer, other gastrointestinal cancers, hormone-related cancers, and lymphoma, in patients with fecal incontinence.

METHODS

Using Danish population-based registries, all patients with hospital-based diagnoses of fecal incontinence during 1995-2013 were identified. We calculated cumulative incidences of cancers. As a measure of relative risks, we computed standardized incidence ratios (SIRs), that is, the observed number of cancers relative to the expected number based on national incidence rates by sex, age, and calendar year.

RESULTS

Among 16 556 patients with fecal incontinence, the cumulative incidence of colorectal cancers, other gastrointestinal cancers, hormone-related cancers, and lymphoma each was less than 0.4% after 1 year. It increased to under 3% after 10 years. The SIR for any cancer during 19 years of follow-up was 1.12 [95% confidence interval (CI), 1.06-1.19]. The SIRs during the first year were 2.31 (95% CI, 1.65-3.13) for colorectal cancer, 1.56 (95% CI, 0.89-2.54) for other gastrointestinal cancers, 1.00 (95% CI, 0.72-1.35) for hormone-related cancers, and 2.02 (95% CI, 1.01-3.61) for lymphoma. Beyond 1 year, the SIR reached unity for other gastrointestinal cancers, hormone-related cancers, and lymphoma, while a reduced risk was observed for colorectal cancer (SIR = 0.77, 95% CI, 0.59-0.98).

CONCLUSIONS

Fecal incontinence was a marker of cancer, especially gastrointestinal cancers and lymphoma within 1 year, which presumably is driven partly by reverse causation. However, the absolute risks were low. Heightened diagnostic efforts may explain in part the increased short-term risk of colorectal cancers.

Risk of thromboembolic and bleeding outcomes following hematological cancers: A Danish population-based cohort study

BACKGROUND

Therapeutic advances have improved survival after hematological cancers. In turn, patients may be at increased risk of thromboembolic and bleeding events.

OBJECTIVES

To examine the risks of myocardial infarction (MI), ischemic stroke, venous thromboembolism (VTE), and bleeding requiring hospital contact in patients with hematological cancers.

METHODS

We conducted a Danish population-based cohort study (2000-2013). We identified all adult hematological cancer patients and sampled a general population comparison cohort in a 1:5 ratio matched by age, sex, previous thromboembolic events, bleeding, and solid cancer. Ten-year absolute risks of thromboembolism and bleeding were calculated and hazard ratios (HRs) were computed, controlling for matching factors.

RESULTS

Among 32 141 hematological cancer patients, the 10-year absolute risk of any thromboembolic or bleeding complication following hematological cancer was 19%: 3.3% for MI, 3.5% for ischemic stroke, 5.2% for VTE, and 8.5% for bleeding. Except among patients with myeloid leukemia, acute lymphoid leukemia, or myelodysplastic syndrome, the risk of thromboembolic events surpassed that of bleeding. The hematological cancer cohort overall was at increased risk for MI [HR = 1.36, 95% confidence interval (CI): 1.25-1.49], ischemic stroke (HR = 1.22, 95% CI: 1.12-1.33), VTE (HR = 3.37, 95% CI: 3.13-3.64), and bleeding (HR = 2.39, 95% CI: 2.26-2.53) compared with the general population.

CONCLUSIONS

Approximately 2 of 10 hematological cancer patients experienced MI, ischemic stroke, VTE, or bleeding requiring hospital contact within 10 years. The hematological cancer cohort had higher hazards of MI, ischemic stroke, VTE, and bleeding requiring hospital contact than a general population comparison cohort.

The Danish health care system and epidemiological research: from health care contacts to database records

Denmark has a large network of population-based medical databases, which routinely collect high-quality data as a by-product of health care provision. The Danish medical databases include administrative, health, and clinical quality databases. Understanding the full research potential of these data sources requires insight into the underlying health care system. This review describes key elements of the Danish health care system from planning and delivery to record generation. First, it presents the history of the health care system, its overall organization and financing. Second, it details delivery of primary, hospital, psychiatric, and elderly care. Third, the path from a health care contact to a database record is followed. Finally, an overview of the available data sources is presented. This review discusses the data quality of each type of medical database and describes the relative technical ease and cost-effectiveness of exact individual-level linkage among them. It is shown, from an epidemiological point of view, how Denmark’s population represents an open dynamic cohort with complete long-term follow-up, censored only at emigration or death. It is concluded that Denmark’s constellation of universal health care, long-standing routine registration of most health and life events, and the possibility of exact individual-level data linkage provides unlimited possibilities for epidemiological research.

Predictors for repeated hyperkalemia and potassium trajectories in high-risk patients - A population-based cohort study

Understanding predictors and trajectories of increased potassium may inform testing and treatment of hyperkalemia. We examined predictors for repeated hyperkalemia among patients after first-time renin angiotensin system inhibitor (RASi) prescription, chronic kidney disease (CKD), or chronic heart failure (CHF); and we also examined potassium trajectories in these patients after their first hyperkalemia event. We used Danish population-based registries to identify all patients with first-time RASi prescription, incident CKD, or incident CHF (2000–2012). For patients with a first hyperkalemia event, potassium trajectories over the following 6 months were examined. The predictors associated with repeated hyperkalemia were assessed, with repeated hyperkalemia defined as a potassium test >5.0 mmol/L after the first event within 6 months. Overall 262,375 first-time RASi users, 157,283 incident CKD patients, and 14,600 incident CHF patients were included. Of patients with a first hyperkalemia event, repeated hyperkalemia within 6 months occurred in 37% of RASi users, 40% with CKD, and 49% of patients with CHF. Predictors included severe hyperkalemia, low eGFR, diabetes, and spironolactone use. In all cohorts, the median potassium levels declined over 2–4 weeks after a hyperkalemia event for the first time, but reverted to levels higher than before the initial hyperkalemia event in those who had repeated hyperkalemia. Following hyperkalemia, discontinuation of RASi and spironolactone was common in the RASi and CHF cohorts. Repeated hyperkalemia was common among the explored cohorts. The first hyperkalemia event was an indicator of increased median potassium levels. Predictors may identify patients likely to benefit from intensified monitoring and intervention.

Venous Thromboembolism in Denmark: Seasonality in Occurrence and Mortality

Background  Many cardiovascular conditions exhibit seasonality in occurrence and mortality, but little is known about the seasonality of venous thromboembolism.

Methods  Using Danish registries, we identified all patients with deep vein thrombosis, pulmonary embolism, splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis during 1977–2016. We tallied monthly deaths occurring within 90 days of the venous thromboembolism diagnosis. We estimated peak-to-trough ratios and timing of the peak of both diagnoses and deaths summed over all years of the study period. The departure from 1.0 of the peak-to-trough ratio measures the intensity of any seasonal pattern.

Results  We estimated a peak-to-trough ratio of 1.09 (95% confidence interval: 1.07–1.11) for deep vein thrombosis and 1.22 (1.19–1.24) for pulmonary embolism occurrence. The peak-to-trough ratios for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis occurrence were 1.10 (1.01–1.20), 1.19 (1.00–1.40), and 1.12 (1.07–1.17), respectively. The occurrence of all conditions peaked during winter or fall. In time trend analyses, the peak-to-trough ratio increased considerably for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis occurrence. In associated mortality, the peak-to-trough ratio for deep vein thrombosis was larger (1.15, 1.07–1.23) than that for pulmonary embolism (1.04, 1.01–1.08).

Discussion  Excess winter risks were modest, but more marked for pulmonary embolism occurrence than for deep vein thrombosis occurrence. The seasonal pattern intensified throughout the study period for splanchnic vein thrombosis, cerebral vein thrombosis, and retinal vein thrombosis. The winter peak in mortality following pulmonary embolism was smaller than that for deep vein thrombosis.

Cardiovascular and bleeding outcomes in a population-based cohort of patients with chronic immune thrombocytopenia

Essentials Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet count. We conducted a cohort study of 3 584 chronic ITP patients from the Nordic countries. Cardiovascular events occurred across all platelet count levels. Cardiovascular or bleeding events were strong prognostic factors for all-cause mortality. Background Among patients with chronic immune thrombocytopenia (cITP), little is known regarding risk factors for cardiovascular and bleeding outcomes and how these events influence mortality. Objectives We examined the rate of cardiovascular events and bleeding requiring a hospital contact according to platelet count levels, as well as the prognostic impact of these events on all-cause mortality in adult patients with cITP. Methods We identified all cITP patients registered in the Nordic Country Patient Registry for Romiplostim during 1996 to 2015. Absolute risks and hazard ratios across platelet count levels based on Cox regression analysis were computed, adjusting for age, sex, prevalent/incident cITP, smoking, and comorbidities. We also compared all-cause mortality rates in cITP patients with and without cardiovascular and bleeding events. Results Among 3 584 cITP patients, 1-year risks were 1.9% for arterial cardiovascular events, 1.2% for venous thromboembolism, and 7.5% for bleeding. Rates of cardiovascular events were similar across platelet counts. Patients with platelet counts <50 × 109 /L had >2-fold higher rates of bleeding than patients with normal platelet counts. These associations were unchanged in time-varying analyses that considered changes in platelet counts during follow-up. Occurrences of cardiovascular and bleeding events were associated with 4-fold to 5-fold increases in 1-year mortality. Conclusions Among patients with cITP, the 1-year risks of cardiovascular events were 1% to 2%, while nearly 8% experienced a bleeding event within 1 year. Cardiovascular events occurred across all platelet levels, while low platelet counts were associated with increased hazards of bleeding. Cardiovascular and bleeding events were strong prognostic factors for mortality.