Existing data sources for clinical epidemiology: The Danish National Database of Reimbursed Prescriptions

The Danish National Patient Registry: a review of content, data quality, and research potential

Background

The Danish National Patient Registry (DNPR) is one of the world’s oldest nationwide hospital registries and is used extensively for research. Many studies have validated algorithms for identifying health events in the DNPR, but the reports are fragmented and no overview exists.

Objectives

To review the content, data quality, and research potential of the DNPR.

Methods

We examined the setting, history, aims, content, and classification systems of the DNPR. We searched PubMed and the Danish Medical Journal to create a bibliography of validation studies. We included also studies that were referenced in retrieved papers or known to us beforehand. Methodological considerations related to DNPR data were reviewed.

Results

During 1977–2012, the DNPR registered 8,085,603 persons, accounting for 7,268,857 inpatient, 5,953,405 outpatient, and 5,097,300 emergency department contacts. The DNPR provides nationwide longitudinal registration of detailed administrative and clinical data. It has recorded information on all patients discharged from Danish nonpsychiatric hospitals since 1977 and on psychiatric inpatients and emergency department and outpatient specialty clinic contacts since 1995. For each patient contact, one primary and optional secondary diagnoses are recorded according to the International Classification of Diseases. The DNPR provides a data source to identify diseases, examinations, certain in-hospital medical treatments, and surgical procedures. Long-term temporal trends in hospitalization and treatment rates can be studied. The positive predictive values of diseases and treatments vary widely (<15%–100%). The DNPR data are linkable at the patient level with data from other Danish administrative registries, clinical registries, randomized controlled trials, population surveys, and epidemiologic field studies – enabling researchers to reconstruct individual life and health trajectories for an entire population.

Conclusion

The DNPR is a valuable tool for epidemiological research. However, both its strengths and limitations must be considered when interpreting research results, and continuous validation of its clinical data is essential.

Rheumatoid Arthritis: Trends in Antirheumatic Drug Use, C-reactive Protein Levels, and Surgical Burden

Objective.

Over the past decade, the therapeutic approach used to treat patients with rheumatoid arthritis (RA) has considerably changed. It remains unclear whether these changes have been accompanied by decreased disease severity and surgical treatment burden at the population level. Therefore, we investigated time trends in antirheumatic drug consumption, C-reactive protein (CRP) levels, and use of orthopedic surgery among Danish patients with RA.

Methods.

Using medical databases, we identified all patients with RA living in Northern Denmark during 1996–2012. For each calendar year, we computed the annual rate of antirheumatic drug use (1996–2010), the median CRP value in mg/l (1996–2011), and the proportions of patients who underwent hip replacement and other orthopedic procedures (1996–2012).

Results.

Antirheumatic drug consumption per patient increased 5-fold, from 145.0 defined daily doses (DDD) in 1996 to 695.4 DDD in 2010. Median CRP declined from 20.5 mg/l [interquartile range (IQR), 10.0 to 43.5 mg/l] in 1996 to 10.0 mg/l (IQR, 4.2–17.8 mg/l) in 2011. From 1996 to 2012, declining proportions of patients with RA underwent hip replacement (14.9% to 10.1%) and other joint operations (29.1% to 23.4%), while the annual proportion of patients who underwent soft tissue procedures increased from 20.7% to 23.4%.

Conclusion.

Antirheumatic drug consumption has substantially increased among patients with RA since 1996, in association with reduced disease activity (i.e., lower CRP levels), fewer joint procedures (including hip replacements), and more soft tissue procedures.

The impact of preadmission oral bisphosphonate use on 30-day mortality following stroke: a population-based cohort study of 100,043 patients

Purpose

Bisphosphonate use has been associated with increased risk of fatal stroke. We examined the association between preadmission use of oral bisphosphonates and 30-day mortality following hospitalization for stroke.

Patients and methods

We conducted a nationwide population-based cohort study using medical databases and identified all patients in Denmark with a first-time hospitalization for stroke between 1 July 2004 and 31 December 2012 (N=100,043). Cox regression was used to compute adjusted hazard ratios as a measure of 30-day mortality rate ratios (MRRs) associated with bisphosphonate current use (prescription filled within 90 days prior to the stroke) or recent use (prescription filled in the 90–180 days prior to the stroke). Current use was further classified as new or long-term use.

Results

We found 51,982 patients with acute ischemic stroke (AIS), 11,779 with intracerebral hemorrhage (ICH), 4,528 with subarachnoid hemorrhage (SAH), and 31,754 with unspecified stroke. Absolute 30-day mortality risks were increased among current vs nonusers of bisphosphonates for AIS (11.9% vs 8.5%), ICH (43.2% vs 34.5%), SAH (40.3% vs 23.2%), and unspecified strokes (18.8% vs 14.0%). However, in adjusted analyses, current bisphosphonate use did not increase 30-day mortality from AIS (MRR, 0.87; 95% confidence interval [CI]: 0.75, 1.01); ICH (MRR, 1.05; 95% CI: 0.90, 1.23); SAH (MRR, 1.15; 95% CI: 0.83, 1.61); or unspecified stroke (MRR, 0.94; 95% CI: 0.81, 1.09). Likewise, no association with mortality was found for recent use. Adjusted analyses by type of bisphosphonate showed increased mortality following stroke among new users of etidronate (MRR, 1.40; 95% CI: 1.01, 1.93) and reduced mortality after AIS among current users of alendronate (MRR, 0.87; 95% CI: 0.74, 1.02).

Conclusion

We found no overall evidence that preadmission bisphosphonate use increases 30-day mortality following stroke.

The Effect of Medical Treatment of Attention Deficit Hyperactivity Disorder (ADHD) on Foster Care Caseloads: Evidence from Danish Registry Data

Since the early 2000s, foster care caseloads have decreased in many wealthy democracies, yet the causes of these declines remain, for the most part, a mystery. This article uses administrative data on all Danish municipalities (N = 277) and a 10% randomly drawn sample of all Danish children (N = 157,938) in the period from 1998 to 2010 to show that increasing medical treatment of attention deficit hyperactivity disorder (ADHD) accounts for a substantial share of the decrease in foster care caseloads. According to our estimates, the decline in foster care caseloads during this period would have been 45% smaller absent increases in medical treatment of ADHD. These findings are especially provocative in light of recent research showing ambiguous effects of medical treatment of ADHD. Future research should be attentive to how medical treatment aimed at addressing children's acute behavioral problems could also have a powerful effect on foster care caseloads.

Pre-existing atrial fibrillation and risk of arterial thromboembolism and death in intensive care unit patients: a population-based cohort study

INTRODUCTION

Pre-existing atrial fibrillation (AF) may worsen prognosis in patients admitted to the intensive care unit (ICU).

METHODS

In a cohort study (2005-2011) including all patients with first-time ICU admissions in Denmark (n=57,110), we compared patients with and without pre-existing AF and estimated absolute risks and relative risks (RRs) of arterial thromboembolism and death within 30 days and 365 days following admission, using Kaplan-Meier methods and multivariate regression analyses. We analysed the prognostic impact of AF within strata of patient age, sex, coexisting cardiac diseases, and ICU therapies.

RESULTS

Among ICU patients, 5065 (9%) had pre-existing AF. Compared with patients without AF, those with AF were older (median age 75 vs. 62 years) and had more comorbidity. The risk of arterial thromboembolism was 2.8% in patients with AF and 2.0% in non-AF patients at 30 days, and 4.3% and 2.9%, respectively, at 365 days. Corresponding RRs were 1.41 crude and 1.14 (95% confidence interval [CI] 0.93-1.40) adjusted at 30 days, and 1.50 crude and 1.20 (95% CI 1.02-1.41) adjusted at 365 days. Thirty-day mortality was 27% in patients with pre-existing AF and 16% in non-AF patients (crude RR 1.67, adjusted RR 1.04, 95% CI 0.99-1.10). Corresponding mortality estimates at 365 days were 40.9% and 25.4%, respectively (crude RR 1.61, adjusted RR 1.03, 95% CI 1.00-1.07). In stratified analyses, pre-existing AF increased mortality in ICU patients aged <55 years (adjusted RR at 30 days 1.73, 95% CI 1.29-2.32; adjusted RR at 365 days 1.34, 95% CI 1.06-1.69) and in ICU patients treated with mechanical ventilation (adjusted RR at 30 days 1.12, 95% CI 1.05-1.20, adjusted RR at 365 days 1.09, 95% CI: 1.04-1.15). Analyses stratified by sex and coexisting cardiac diseases yielded adjusted RRs close to 1.

CONCLUSIONS

In ICU patients, pre-existing AF was associated with modestly increased risk of arterial thromboembolism when adjusted for the substantially higher age and comorbidity levels in patients with AF, whereas there was no overall association with mortality. In ICU patients aged <55 years and in those treated with mechanical ventilation, AF predicted increased mortality.

Healthcare Contacts after Myocardial Infarction According to Mental Health and Socioeconomic Position: A Population-Based Cohort Study

OBJECTIVE

To examine the long-term use of healthcare contacts to general practice (GP) and hospital after a first-time myocardial infarction (MI) according to mental health and socioeconomic position.

METHODS

Population-based cohort study of all patients discharged with first-time MI in the Central Denmark Region in 2009 (n=908) using questionnaires and nationwide registers. We estimated adjusted incidence rates and incidence rate ratios (IRR) for GP and hospital contacts according to depressive and anxiety symptoms, educational level and cohabitation status.

RESULTS

During the 24-month period after the MI, patients with anxiety symptoms had 24% more GP contacts (adjusted IRR 1.24, 95% confidence interval (CI) 1.12-1.36) than patients with no anxiety symptoms. In contrast, patients with depressive symptoms (1.05, 0.94-1.16) and with short and medium education (<10 years: 0.96, 0.84-1.08; 10-12 years: 0.91, 0.80-1.03) and patients living alone (0.95, 0.87-1.04) had the same number of GP contacts as their counterparts (patients with no depressive symptoms, with long education [>12 years] and patients living with a partner). During the first 6 months after the MI, patients living alone had 13% fewer hospital contacts (0.87, 0.77-0.99), patients with short education had 16% fewer hospital contacts (<10 years: 0.84, 0.72-0.98) and patients with anxiety symptoms had 27% fewer hospital contacts (0.73, 0.62-0.86) than their counterparts. In contrast, patients with depressive symptoms (0.92, 0.77-1.10) and medium education (10-12 years: 1.05, 0.91-1.22) had the same number of hospital contacts as their counterparts.

CONCLUSIONS

This study indicates that patients with depressive symptoms, short and medium education and patients living alone have a lower long-term use of healthcare contacts following MI than patients without these risk factors. Patients with depressive symptoms and low socioeconomic position would be expected to have a higher need of healthcare after MI as they have a poorer prognosis.

Cirrhosis is Associated with an Increased 30-Day Mortality After Venous Thromboembolism

Objectives:

Patients with cirrhosis are at increased risk of venous thromboembolism (VTE), but the impact of cirrhosis on the clinical course following VTE is unclear. In a nationwide cohort study, we examined 30-day mortality among patients with cirrhosis and VTE.

Methods:

We used Danish population-based health-care databases (1994–2011) to identify patients with incident VTE, i.e., deep venous thrombosis (DVT), pulmonary embolism (PE), and portal vein thrombosis (PVT). Among these, we identified 745 patients with cirrhosis and 3647 patients without cirrhosis (matched on gender, year of birth, calendar year of VTE diagnosis and VTE type). We assessed the 30-day mortality risk among VTE patients with and without cirrhosis, and the mortality rate ratios (MRRs), using an adjusted Cox model with 95% confidence interval. We obtained information on immediate cause of death for patients who died within 30 days after VTE.

Results:

The 30-day mortality risk for DVT was 7% for patients with cirrhosis and 3% for patients without cirrhosis. Corresponding PE-related mortality risks were 35% and 16%, and PVT-related mortality risks were 19% and 15%, respectively. The adjusted 30-day MRRs were 2.17 (1.24–3.79) for DVT, 1.83 (1.30–2.56) for PE, and 1.30 (0.80–2.13) for PVT. Though overall mortality was higher in patients with cirrhosis than patients without cirrhosis, the proportions of deaths due to PE were similar among patients (25% and 24%, respectively).

Conclusions:

Cirrhosis is a predictor for increased short-term mortality following VTE, with PE as the most frequent cause of death.

Preadmission use of ACE inhibitors or angiotensin receptor blockers and short-term mortality after stroke

BACKGROUND AND AIM

The prognostic impact of ACE inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) on stroke mortality remains unclear. We aimed to examine whether prestroke use of ACE-Is or ARBs was associated with improved short-term mortality following ischaemic stroke, intracerebral haemorrhage (ICH) and subarachnoid haemorrhage (SAH).

METHODS

We conducted a nationwide population-based cohort study using medical registries in Denmark. We identified all first-time stroke patients during 2004-2012 and their comorbidities. We defined ACE-I/ARB use as current use (last prescription redemption <90 days before admission for stroke), former use and non-use. Current use was further classified as new or long-term use. We used Cox regression modelling to compute 30-day mortality rate ratios (MRRs) with 95% CIs, controlling for potential confounders.

RESULTS

We identified 100 043 patients with a first-time stroke. Of these, 83 736 patients had ischaemic stroke, 11 779 had ICH, and 4528 had SAH. For ischaemic stroke, the adjusted 30-day MRR was reduced in current users compared with non-users (0.85, 95% CI 0.81 to 0.89). There was no reduction in the adjusted 30-day MRR for ICH (0.95, 95% CI 0.87 to 1.03) or SAH (1.01, 95% CI 0.84 to 1.21), comparing current users with non-users. No association with mortality was found among former users compared with non-users. No notable modification of the association was observed within sex or age strata.

CONCLUSIONS

Current use of ACE-Is/ARBs was associated with reduced 30-day mortality among patients with ischaemic stroke. We found no association among patients with ICH or SAH.

Incretin-based therapy and risk of acute pancreatitis: a nationwide population-based case-control study

OBJECTIVE

To investigate whether the use of incretin-based drugs (GLP-1 receptor agonists and dipeptidyl peptidase 4 [DPP4] inhibitors) is associated with acute pancreatitis.

RESEARCH DESIGN AND METHODS

The study was a nationwide population-based case-control study using medical databases in Denmark. Participants were 12,868 patients with a first-time hospitalization for acute pancreatitis between 2005 and 2012 and a population of 128,680 matched control subjects. The main outcome measure was the odds ratio (OR) for acute pancreatitis associated with different antihyperglycemic drugs. We adjusted for history of gallstones, alcoholism, obesity, and other pancreatitis-associated comorbidities and medications.

RESULTS

A total of 89 pancreatitis patients (0.69%) and 684 control subjects (0.53%) were ever users of incretins. The crude OR for acute pancreatitis among incretin users was 1.36 (95% CI 1.08-1.69), while it was 1.44 (95% CI 1.34-1.54) among users of other antihyperglycemic drugs. After confounder adjustment, the risk of acute pancreatitis was not increased among incretin users (OR 0.95 [95% CI 0.75-1.21]), including DPP4 inhibitor users (OR 1.04 [95% CI 0.80-1.37]) or GLP-1 receptor agonist users (OR 0.82 [95% CI 0.54-1.23]), or among nonincretin antihyperglycemic drug users (OR 1.05 [95% CI 0.98-1.13]), compared with nonusers of any antihyperglycemic drugs. Findings were similar in current versus ever drug users and in patients with pancreatitis risk factors. The adjusted OR comparing incretin-based therapy with other antihyperglycemic therapy internally while also adjusting for diabetes duration and complications was 0.97 (95% CI 0.76-1.23).

CONCLUSIONS

Our findings suggest that the use of incretin-based drugs appears not to be associated with an increased risk of acute pancreatitis.

The "true" incidence of surgically treated deep prosthetic joint infection after 32,896 primary total hip arthroplasties: a prospective cohort study

BACKGROUND AND PURPOSE

It has been suggested that the risk of prosthetic joint infection (PJI) in patients with total hip arthroplasty (THA) may be underestimated if based only on arthroplasty registry data. We therefore wanted to estimate the "true" incidence of PJI in THA using several data sources.

PATIENTS AND METHODS

We searched the Danish Hip Arthroplasty Register (DHR) for primary THAs performed between 2005 and 2011. Using the DHR and the Danish National Register of Patients (NRP), we identified first revisions for any reason and those that were due to PJI. PJIs were also identified using an algorithm incorporating data from microbiological, prescription, and clinical biochemistry databases and clinical findings from the medical records. We calculated cumulative incidence with 95% confidence interval.

RESULTS

32,896 primary THAs were identified. Of these, 1,546 had first-time revisions reported to the DHR and/or the NRP. For the DHR only, the 1- and 5-year cumulative incidences of PJI were 0.51% (0.44-0.59) and 0.64% (0.51-0.79). For the NRP only, the 1- and 5-year cumulative incidences of PJI were 0.48% (0.41-0.56) and 0.57% (0.45-0.71). The corresponding 1- and 5-year cumulative incidences estimated with the algorithm were 0.86% (0.77-0.97) and 1.03% (0.87-1.22). The incidences of PJI based on the DHR and the NRP were consistently 40% lower than those estimated using the algorithm covering several data sources.

INTERPRETATION

Using several available data sources, the "true" incidence of PJI following primary THA was estimated to be approximately 40% higher than previously reported by national registries alone.

The Danish National Prescription Registry in studies of a biological pharmaceutical: palivizumab - validation against two external data sources

Background

National prescription databases are important tools in pharmacoepidemiological studies investigating potential long-term adverse events after drug use. Palivizumab is a biological pharmaceutical used as passive prophylaxis against severe infection with respiratory syncytial virus in high-risk children.

Objective

To assess the registration of palivizumab in the Danish National Prescription Registry (DNPR) and to examine if palivizumab reimbursement data obtained from the Danish Health and Medicines Authority could serve as a supplement to data from the DNPR.

Methods

Registration of palivizumab exposure in the DNPR between 1999 and 2010 was compared to two external data sources: registration of palivizumab exposure in medical records, and palivizumab reimbursement data.

Results

During the study period, 182 children with palivizumab exposure were registered in the DNPR. A total of 207 children were registered for palivizumab reimbursement. The sensitivity of palivizumab registration in the DNPR was 26% (20%–34%), and the specificity of no palivizumab registration in the DNPR was 97% (94%–99%), with data from the medical record as the reference. Palivizumab registration sensitivity in reimbursement data was 29% (22%–36%), and the specificity of no palivizumab registration in the DNPR was 97% (94%–99%), with data from the medical record as the reference.

Conclusion

Exposure to palivizumab was underestimated in the DNPR. Reimbursement data are a readily accessible data supplement, which only slightly increased the sensitivity of palivizumab registration in the DNPR. Our findings underline the need to improve DNPR information concerning drugs administered in hospitals.

Mortality in cancer patients previously diagnosed with herpes zoster in the hospital setting: a nationwide cohort study

Background:

Herpes zoster (HZ) is associated with underlying immunodeficiency and may thereby predict mortality of subsequent cancer.

Methods:

By using Danish nationwide medical databases, we identified all cancer patients with a prior hospital-based HZ diagnosis during 1982–2011 (n=2754) and a matched cancer cohort without prior HZ (n=26 243). We computed adjusted mortality rate ratios (aMRRs) associating prior HZ with mortality following cancer.

Results:

Prior HZ was associated with decreased mortality within the year after cancer diagnosis (aMRR 0.87; 95% confidence interval (CI): 0.81–0.93), but not thereafter (aMRR 1.07; 95% CI: 0.99–1.15). However, prior HZ predicted increased mortality throughout the entire follow-up among patients aged <60 years (aMRR 1.39; 95% CI: 1.15–1.68) and those with disseminated HZ (aMRR 1.18; 95% CI: 1.01–1.37). The increased mortality rates were observed primarily for haematological and immune-related cancers.

Conclusions:

Overall, HZ was not a predictor of increased mortality following subsequent cancer.

Time-dependent effect of preinfarction angina pectoris and intermittent claudication on mortality following myocardial infarction: A Danish nationwide cohort study

BACKGROUND

As proxies for local and remote ischemic preconditioning, we examined whether preinfarction angina pectoris and intermittent claudication influenced mortality following myocardial infarction.

METHODS

Using medical registries, we conducted a nationwide population-based cohort study of all first-time myocardial infarction patients in Denmark during 2004-2012 (n=70,458). We computed all-cause and coronary mortality rate ratios (MRRs). We categorized time between angina/claudication presentation and subsequent myocardial infarction as 0-14, 15-30, 31-90, and > 90 days. We adjusted for age, sex, coronary intervention, comorbidities, and medication use.

RESULTS

Among all myocardial infarction patients, 18.4% had prior angina and 3.8% had prior intermittent claudication. Compared to patients without prior angina, the adjusted 30-day coronary MRR was 0.85 (95% confidence interval (CI): 0.80-0.92) for stable and 0.68 (95% CI: 0.58-0.79) for unstable angina patients. The mortality reduction increased when angina presented close to myocardial infarction and was higher for unstable than for stable angina. Thus, the 30-day coronary MRR was 0.72 (95% CI: 0.51-1.02) for stable angina and 0.35 (95% CI: 0.17-0.73) for unstable angina presenting within 14 days before MI. The results were robust for all-cause mortality and in numerous subgroups, including women, diabetics, patients treated with PCI, and patients treated with and without cardioprotective drugs. Preinfarction intermittent claudication was associated with higher short- and long-term mortality compared to patients without intermittent claudication.

CONCLUSIONS

Preinfarction angina reduced 30-day mortality, particularly when unstable angina closely preceded MI. Preinfarction intermittent claudication was associated with increased short- and long-term mortality.

Prevalence and characteristics of patients with low levels of low-density lipoprotein cholesterol in northern Denmark: a descriptive study

BACKGROUND

With the emergence of new lipid-lowering therapies, more patients are expected to achieve substantial lowering of low-density lipoprotein cholesterol (LDL-C). However, there are limited data examining the clinical experience of patients with low (<1.3 mmol/L) or very low (<0.65 mmol/L) levels of LDL-C. To provide information on patients with low LDL-C, we identified and characterized persons with low LDL-C using data from Danish medical databases.

METHODS

Using a population-based clinical laboratory database, we identified adults with at least one LDL-C measurement in northern Denmark between 1998 and 2011 (population approximately 1.5 million persons). Based on the lowest measurement during the study period, we divided patients into groups with low (<1.3 mmol/L), moderate (1.3-3.3 mmol/L), or high (>3.3 mmol/L) LDL-C. We described their demographic characteristics, entire comorbidity history, and 90-day prescription history prior to the lowest LDL-C value measured. Finally, we further restricted the analysis to individuals with very low LDL-C (<0.65 mmol/L).

RESULTS

Among 765,503 persons with an LDL-C measurement, 23% had high LDL-C, 73% had moderate LDL-C, and 4.8% had low LDL-C. In the latter group, 9.6% (0.46% of total) had very low LDL-C. Compared with the moderate and high LDL-C categories, the low LDL-C group included more males and older persons with a higher prevalence of cardiovascular disease, diabetes, chronic pulmonary disease, ulcer disease, and obesity, as measured by hospital diagnoses or relevant prescription drugs for these diseases. Cancer and use of psychotropic drugs were also more prevalent. These patterns of distribution became even more pronounced when restricting to individuals with very low LDL-C.

CONCLUSION

Using Danish medical databases, we identified a cohort of patients with low LDL-C and found that cohort members differed from patients with higher LDL-C levels. These differences may be explained by various factors, including prescribing patterns of lipid-lowering therapies.

Impact of preadmission treatment with calcium channel blockers or beta blockers on short-term mortality after stroke: a nationwide cohort study

Background

The prognostic impact of preadmission use of calcium channel blockers (CCBs) and beta blockers (BBs) on stroke mortality remains unclear. We aimed to examine whether preadmission use of CCBs or BBs was associated with improved short-term mortality following ischemic stroke, intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH).

Methods

We conducted a nationwide population-based cohort study using Danish medical registries. We identified all patients with a first-time inpatient diagnosis of stroke between 2004 and 2012 and their comorbidities. We defined CCB/BB use as current use, former use, or non-use. Current use was further classified as new or long-term use. We used Cox regression modeling to compute 30-day mortality rate ratios (MRRs) with 95% confidence intervals (CIs), controlling for potential confounders.

Results

We identified 100,043 patients with a first-time stroke. Of these, 83,736 (83.7%) patients had ischemic stroke, 11,779 (11.8%) had ICH, and 4,528 (4.5%) had SAH. Comparing current users of CCBs or BBs with non-users, we found no association with mortality for ischemic stroke [adjusted 30-day MRR = 0.99 (95% CI: 0.94-1.05) for CCBs and 1.01 (95% CI: 0.96-1.07) for BBs], ICH [adjusted 30-day MRR = 1.05 (95% CI: 0.95-1.16) for CCBs and 0.95 (95% CI: 0.87-1.04) for BBs], or SAH [adjusted 30-day MRR = 1.05 (95% CI: 0.85-1.29) for CCBs and 0.89 (95% CI: 0.72-1.11) for BBs]. Former use of CCBs or BBs was not associated with mortality.

Conclusions

Preadmission use of CCBs or BBs was not associated with 30-day mortality following ischemic stroke, ICH, or SAH.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-015-0279-3) contains supplementary material, which is available to authorized users.

Preoperative glucocorticoid use and risk of postoperative bleeding and infection after gastric bypass surgery for the treatment of obesity

BACKGROUND

Previous research suggests that patients using glucocorticoids may be at increased risk of postoperative bleeding and infection after major surgery. The objective was to investigate the association between preoperative glucocorticoid use and risk of bleeding and infection after Roux-en-Y gastric bypass surgery (RYGB).

SETTING

Nationwide cohort study of 13,195 patients, who underwent RYGB 2006-2012 using Danish population-based medical databases.

METHODS

Information was obtained on current (redeemed prescription<60 d before surgery), recent (prescription 60-180 d before surgery), or no glucocorticoid use, and postoperative bleeding or infection within 30 days of surgery. We computed risk differences and odds ratios (ORs) as a measure of relative risk with 95% confidence intervals (95% CIs) for the association between glucocorticoid use and bleeding or infection, adjusting for gender, age, and co-morbidities by logistic regression.

RESULTS

Among RYGB patients, 325 (2.5%) were current glucocorticoid users, and 365 (2.8%) were recent users. The risk of bleeding was increased in current users: 2.8% versus 1.6% among nonusers (risk difference: 1.2%, 95% CI: -.6, 3.0) corresponding to an adjusted OR of 1.5 (95% CI: .8, 3.0). For recent users, the adjusted OR for bleeding was 1.2 (95% CI: .5, 2.5). The risk of infection did not differ materially between current (1.8%), recent (1.0%) and nonusers (1.7%), corresponding to an adjusted OR of .9 (95% CI: .4, 2.1) among current versus nonusers.

CONCLUSIONS

Current use of glucocorticoids is associated with a slightly increased risk of postoperative bleeding, but not infection, after RYGB. No increased risks were found for recent users.

The Western Denmark Cardiac Computed Tomography Registry: a review and validation study

BACKGROUND

As a subregistry to the Western Denmark Heart Registry (WDHR), the Western Denmark Cardiac Computed Tomography Registry (WDHR-CCTR) is a clinical database established in 2008 to monitor and improve the quality of cardiac computed tomography (CT) in Western Denmark.

OBJECTIVE

We examined the content, data quality, and research potential of the WDHR-CCTR.

METHODS

We retrieved 2008-2012 data to examine the 1) content; 2) completeness of procedure registration using the Danish National Patient Registry as reference; 3) completeness of variable registration comparing observed vs expected numbers; and 4) positive predictive values as well as negative predictive values of 19 main patient and procedure variables.

RESULTS

By December 31, 2012, almost 22,000 cardiac CTs with up to 40 variables for each procedure have been registered. Of these, 87% were coronary CT angiography performed in patients with symptoms indicative of coronary artery disease. Compared with the Danish National Patient Registry, the overall procedure completeness was 72%. However, an additional medical record review of 282 patients registered in the Danish National Patient Registry, but not in the WDHR-CCTR, showed that coronary CT angiographies accounted for only 23% of all nonregistered cardiac CTs, indicating >90% completeness of coronary CT angiographies in the WDHR-CCTR. The completeness of individual variables varied substantially (range: 0%-100%), but was >85% for more than 70% of all variables. Using medical record review of 250 randomly selected patients as reference standard, the positive predictive value for the 19 variables ranged from 89% to 100% (overall 97%), whereas the negative predictive value ranged from 97% to 100% (overall 99%). Stratification by center status showed consistently high positive and negative predictive values for both university (96%/99%) and nonuniversity centers (97%/99%).

CONCLUSION

WDHR-CCTR provides ongoing prospective registration of all cardiac CTs performed in Western Denmark since 2008. Overall, the registry data have a high degree of completeness and validity, making it a valuable tool for clinical epidemiological research.

Effectiveness and safety of different duration of thromboprophylaxis in 16,865 hip replacement patients--a real-word, prospective observational study

INTRODUCTION

Clinical trials have provided evidence about efficacy and safety of extended thromboprophylaxis among total hip replacement (THR) patients. There is a lack of evidence on effectiveness and safety of extended treatment in unselected patients from routine clinical practice. We examined the effectiveness and safety of short (1-6 days) and standard (7-27 days) compared with extended (≥28 days) thromboprophylaxis using population-based design.

MATERIAL AND METHODS

Among all primary THR procedures performed in Denmark from 2010 through 2012 (n=16,865), we calculated adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for risk of symptomatic venous thromboembolism (VTE) and major bleeding, in addition to net clinical benefit, defined as the number of VTE avoided minus the number of excess bleeding events occurring among patients prescribed short-term and standard versus extended treatment.

RESULTS

The 90-day risks of VTE were 1.1% (short), 1.4% (standard), and 1.0% (extended), yielding aHRs of 0.83 (95% CI: 0.52-1.31) and 0.82 (95% CI: 0.50-1.33) for short and standard versus extended treatment. The risk of major bleeding was 1.1% (short), 1.0% (standard), and 0.7% (extended), resulting in aHRs of 1.64 (95% CI: 0.83-3.21) and 1.24 (95%CI: 0.61-2.51) for short and standard versus extended thromboprophylaxis. Direct comparison between benefits and harms using net clinical benefit analyses did not favor any of the three treatment durations. The same results were found for VTE or death.

CONCLUSIONS

In a real-word observational cohort of unselected THR patients, we observed no difference in the risks of symptomatic VTE, VTE/ death or bleeding with respect to thromboprophylaxis duration.

Risk of venous and arterial thrombotic events in patients diagnosed with superficial vein thrombosis: a nationwide cohort study

Recently, it has become apparent that superficial vein thrombosis (SVT) can have serious complications. However, the magnitude of the risk of subsequent deep venous and arterial thrombotic events remains unknown. We examined this in a nationwide population-based setting during a period when SVT was not treated routinely with anticoagulants. The Danish National Registry of Patients, covering all Danish hospitals, was used to identify 10 973 patients with a first-time diagnosis of SVT between 1980 and 2012. A comparison cohort of 515 067 subjects, matched by age, gender, and calendar year, was selected from the general Danish population. Outcomes were venous thromboembolism, acute myocardial infarction, ischemic stroke, and death. During median follow-up of 7 years, the incidence rate of venous thromboembolism was 18.0/1000 person-years (95% confidence interval [CI], 17.2-18.9). The highest risk occurred in the first 3 months (3.4%; 95% CI, 3.0-3.7). Compared with the general population, the hazard ratio was 71.4 (95% CI, 60.2-84.7) in this period, steadily decreasing to 5.1 (95% CI 4.6-5.5), 5 years after the SVT. The hazard ratios for acute myocardial infarction, stroke, and death were 1.2 (95% CI, 1.1-1.3), 1.3 (95% CI, 1.2-1.4), and 1.3 (95% CI, 1.2-1.3), respectively, with the highest risk also shortly after SVT. These data indicate the prognostic importance of SVT and may form the basis for clinical decision-making regarding anticoagulation.

Modifiable clinical and lifestyle factors are associated with elevated alanine aminotransferase levels in newly diagnosed type 2 diabetes patients: results from the nationwide DD2 study

BACKGROUND

Current literature lacks data on markers of non-alcoholic fatty liver disease (NAFLD) in newly diagnosed type 2 diabetes mellitus (T2DM) patients. We therefore, conducted a cross-sectional study to examine modifiable clinical and lifestyle factors associated with elevated alanine aminotransferase (ALT) levels as a marker of NAFLD in new T2DM patients.

METHODS

Alanine aminotransferase levels were measured in 1026 incident T2DM patients enrolled in the nationwide Danish Centre for Strategic Research in Type 2 Diabetes (DD2) cohort. We examined prevalence of elevated ALT (>38 IU/L for women and >50 IU/L for men) and calculated prevalence ratios associated with clinical and lifestyle factors using Poisson regression. We examined the association with other biomarkers by linear regression.

RESULTS

The median value of ALT was 24 IU/L (interquartile range: 18-32 IU/L) in women and 30 IU/L (interquartile range: 22-41 IU/L) in men. Elevated ALT was found in 16% of incident T2DM patients. The risk of elevated ALT was increased in patients who were <40 years old at diabetes debut [adjusted prevalence ratio (aPR): 1.96, 95% confidence interval (CI): 1.15-3.33], in those with alcohol overuse (>14/>21 drinks per week for women/men) (aPR: 1.60, 95% CI: 1.03-2.50), and in those with no regular physical activity (aPR: 1.42, 95% CI: 1.04-1.93). Obesity and metabolic syndrome per se showed no association with elevated ALT when adjusted for other markers, whereas we found positive associations of ALT with increased C-peptide (β = 0.14, 95% CI: 0.06-0.21) and fasting blood glucose (β = 0.07, 95% CI: 0.03-0.11).

CONCLUSIONS

Among newly diagnosed T2DM patients, several modifiable clinical and lifestyle factors are independent markers of elevated ALT levels.

Duration of thyroid dysfunction correlates with all-cause mortality. the OPENTHYRO Register Cohort

Introduction and Aim

The association between thyroid dysfunction and mortality is controversial. Moreover, the impact of duration of thyroid dysfunction is unclarified. Our aim was to investigate the correlation between biochemically assessed thyroid function as well as dysfunction duration and mortality.

Methods

Register-based follow-up study of 239,768 individuals with a serum TSH measurement from hospitals and/or general practice in Funen, Denmark. Measurements were performed at a single laboratory from January 1st 1995 to January 1st 2011. Cox regression was used for mortality analyses and Charlson Comorbidity Index (CCI) was used as comorbidity score.

Results

Hazard ratios (HR) with 95% confidence intervals (CI) for mortality with decreased (<0.3 mIU/L) or elevated (>4.0 mIU/L) levels of TSH were 2.22; 2.14–2.30; P<0.0001 and 1.28; 1.22–1.35; P<0.0001, respectively. Adjusting for age, gender, CCI and diagnostic setting attenuated the risk estimates (HR 1.23; 95% CI: 1.19–1.28; P<0.0001, mean follow-up time 7.7 years, and HR 1.07; 95% CI: 1.02–1.13; P = 0.004, mean follow-up time 7.2 years) for decreased and elevated values of TSH, respectively. Mortality risk increased by a factor 1.09; 95% CI: 1.08–1.10; P<0.0001 or by a factor 1.03; 95% CI: 1.02–1.04; P<0.0001 for each six months a patient suffered from decreased or elevated TSH, respectively. Subdividing according to degree of thyroid dysfunction, overt hyperthyroidism (HR_overt 1.12; 95% CI: 1.06–1.19; P<0.0001), subclinical hyperthyroidism (HR_subclinical 1.09; 95% CI: 1.02–1.17; P = 0.02) and overt hypothyroidism (HR_overt 1.57; 95% CI: 1.34–1.83; P<0.0001), but not subclinical hypothyroidism (HR_subclinical 1.03; 95% CI: 0.97–1.09; P = 0.4) were associated with increased mortality.

Conclusions and Relevance

In a large-scale, population-based cohort with long-term follow-up (median 7.4 years), overt and subclinical hyperthyroidism and overt but not subclinical hypothyroidism were associated with increased mortality. Excess mortality with increasing duration of decreased or elevated serum TSH suggests the importance of timely intervention in individuals with thyroid dysfunction.

Diverticular disease is associated with increased risk of subsequent arterial and venous thromboembolic events

BACKGROUND & AIMS

Diverticular disease and cardiovascular disease share several risk factors. Inflammation associated with diverticular disease could predispose to cardiovascular disease. We assessed the association between a diagnosis of diverticular disease and subsequent arterial and venous thromboembolic events, adjusting for related comorbidities to explore a possible causal relationship.

METHODS

We identified 77,065 incident cases of diverticular disease from 1980-2011 from Danish nationwide medical registries; these were matched for age and sex with 302,572 population comparison cohort members. Individuals with a history of cardiovascular disease were excluded. We used Cox proportional hazards regression to compute incidence rate ratios, comparing the incidence of acute myocardial infarction, stroke, venous thromboembolism, and subarachnoid hemorrhage in patients with diverticular disease with those of the population cohort members, adjusting for age, sex, obesity, diabetes, hyperlipidemia, chronic obstructive pulmonary disease, connective tissue disease, renal disease, and treatments and medications.

RESULTS

The adjusted incidence rate ratios for patients with diverticular disease, compared with population cohort members, were 1.11 (95% confidence interval [CI], 1.07-1.14) for acute myocardial infarction, 1.11 (95% CI, 1.08-1.15) for overall stroke, 1.36 (95% CI, 1.30-1.43) for overall venous thromboembolism, and 1.27 (95% CI, 1.09-1.48) for subarachnoid hemorrhage. The relative risk of each event remained increased after we adjusted for changes in aspirin use or for endoscopy or colorectal surgery after the diagnosis of diverticular disease. These findings also held after excluding the first year of follow-up and limiting the analysis to patients with diverticulitis.

CONCLUSIONS

On the basis of an analysis of Danish medical registries, a diagnosis of diverticular disease is associated with a modest increase in risk of arterial and venous thromboembolic events after adjustment for related disorders.

Lifestyle and clinical factors associated with elevated C-reactive protein among newly diagnosed Type 2 diabetes mellitus patients: a cross-sectional study from the nationwide DD2 cohort

BACKGROUND

We aimed to examine the prevalence of and modifiable factors associated with elevated C-reactive Protein (CRP), a marker of inflammation, in men and women with newly diagnosed Type 2 Diabetes mellitus (DM) in a population-based setting.

METHODS

CRP was measured in 1,037 patients (57% male) with newly diagnosed Type 2 DM included in the prospective nationwide Danish Centre for Strategic Research in Type 2 Diabetes (DD2) project. We assessed the prevalence of elevated CRP and calculated relative risks (RR) examining the association of CRP with lifestyle and clinical factors by Poisson regression, stratified by gender. We used linear regression to examine the association of CRP with other biomarkers.

RESULTS

The median CRP value was 2.1 mg/L (interquartile range, 1.0 - 4.8 mg/L). In total, 405 out of the 1,037 Type 2 DM patients (40%) had elevated CRP levels (>3.0 mg/L). More women (46%) than men (34%) had elevated CRP. Among women, a lower risk of elevated CRP was observed in patients receiving statins (adjusted RR (aRR) 0.7 (95% confidence interval (CI) 0.6-0.9)), whereas a higher risk was seen in patients with central obesity (aRR 2.3 (95% CI 1.0-5.3)). For men, CRP was primarily elevated among patients with no regular physical activity (aRR 1.5 (95% CI 1.1-1.9)), previous cardiovascular disease (aRR1.5 (95% CI 1.2-1.9) and other comorbidity. For both genders, elevated CRP was 1.4-fold increased in those with weight gain >30 kg since age 20 years. Sensitivity analyses showed consistent results with the full analysis. The linear regression analysis conveyed an association between high CRP and increased fasting blood glucose.

CONCLUSIONS

Among newly diagnosed Type 2 DM patients, 40% had elevated CRP levels. Important modifiable risk factors for elevated CRP may vary by gender, and include low physical activity for men and central obesity and absence of statin use for women.

Statin use and venous thromboembolism recurrence: a combined nationwide cohort and nested case-control study

BACKGROUND

Data on statins' effect on venous thromboembolism (VTE) recurrence are conflicting.

OBJECTIVES

We examined whether statin use was associated with reduced risk of recurrent VTE in a nationwide population-based setting.

PATIENTS/METHODS

Using the Danish National Patient Registry, we identified first-time and recurrent VTEs between 1 July 2004 and 31 December 2012 (n = 27,862). VTE diagnoses were validated by medical record review of a subsample of patients. We ascertained nationwide prescription data and categorized statin use as current (further divided into new and long-term use), former and no use. We identified statin use at baseline (mimicking an intention-to-treat analysis) and in a time-varying manner during follow-up (mimicking per-protocol analysis) and computed hazard ratios (HRs) for recurrent VTE using Cox regression. In a supplementary nested case-control study, we identified statin use at time of VTE recurrence and computed odds ratios as unbiased estimates of the incidence rate ratios (IRRs) using conditional logistic regression. We adjusted for age, sex, year of diagnosis, provoking factors, co-morbidities and co-medications, including time-varying use of aspirin and anticoagulant drugs.

RESULTS

The adjusted HR comparing current use with no use was 0.72 (95% confidence interval [CI], 0.59-0.88) for recurrent VTE, with a stronger effect of high (0.40; 95% CI, 0.21-0.78) vs. low potency statins (0.77; 95% CI, 0.63-0.94). Consistently, the recurrence rate was reduced in both the time-varying analysis (HR=0.64; 95% CI, 0.54-0.77) and nested case-control analysis (IRR=0.55; 95% CI, 0.45-0.67). The effect was largest for recurrent deep venous thrombosis.

CONCLUSIONS

Statin use was associated with reduced VTE recurrence.

From administrative infrastructure to biomedical resource: Danish population registries, the "Scandinavian laboratory," and the "epidemiologist's dream"

Since the 1970s, Danish population registries were increasingly used for research purposes, in particular in the health sciences. Linked with a large number of disease registries, these data infrastructures became laboratories for the development of both information technology and epidemiological studies. Denmark's system of population registries had been centralized in 1924 and was further automated in the 1960s, with individual identification numbers (CPR-numbers) introduced in 1968. The ubiquitous presence of CPR-numbers in administrative routines and everyday lives created a continually growing data archive of the entire population. The resulting national-level database made possible unprecedented record linkage, a feature epidemiologists and biomedical scientists used as a resource for population health research. The specific assemblages that emerged with their practices of data mining were constitutive of registry-based epidemiology as a style of thought and of a distinct relationship between science, citizens, and the state that emerged as “Scandinavian.”

National Surveillance of Central Diabetes Insipidus (CDI) in Denmark: results from 5 years registration of 9309 prescriptions of desmopressin to 1285 CDI patients

CONTEXT

Epidemiological data for central diabetes insipidus (CDI) are sparse.

OBJECTIVE

The purpose of this study was to provide accurate epidemiological data on CDI on a national level.

DESIGN AND SETTING

This was a drug utilization and patient registry study during a 5-year period from 2007 to 2011.

METHODS

We used the Danish National Prescription Registry data linked with the Danish National Patient Registry to study the epidemiology of CDI using waiting time distribution and other pharmacoepidemiological methods.

PATIENTS

A total of 1285 patients with CDI were recorded in the observation period and given 9309 prescriptions for desmopressin in the nasal formulation, orodispersible tablet, or conventional tablet.

RESULTS

The period prevalence rate of CDI in Denmark over the 5-year period investigated was 23 CDI patients per 100 000 inhabitants, with a higher prevalence in children and older adults (>80 years of age). The 1-year period prevalence rate of CDI decreased in Denmark over the 5 years from approximately 10 to 7 CDI patients per 100 000 inhabitants. The yearly incidence rate of new cases of CDI was found to be 3 to 4 patients per 100 000. The incidence of (presumable) congenital CDI was found to be 2 infants per 100 000 infants. Half of the patients with CDI prescribed as oral treatment were provided dosing instructions to only administer the drug before bedtime, and one third of the CDI patients either had no specific instructions or were instructed to use the drug as needed. Hospital admissions due to severe hyponatremia occurred in 0.9% of patients over a 5-year period, predominantly in females with an incidence ratio of women to men of 1.8:1.

CONCLUSION

Half of the cases of CDI are acquired later in life. At least half of the patients with CDI are instructed to prevent nocturnal polyuria, but it is not clear whether their CDI remains uncontrolled during the daytime or, alternatively, whether they use desmopressin only as needed. Female patients with CDI had approximately twice the number of hospital admissions due to severe hyponatremia than male patients with CDI.

Potential of prescription registries to capture individual-level use of aspirin and other nonsteroidal anti-inflammatory drugs in Denmark: trends in utilization 1999-2012

BACKGROUND

Due to over-the-counter availability, no consensus exists on whether adequate information on nonsteroidal anti-inflammatory drug (NSAID) use can be obtained from prescription registries.

OBJECTIVES

To examine utilization of aspirin and nonaspirin NSAIDs in Denmark between 1999 and 2012 and to quantify the proportion of total sales that was sold on prescription.

METHOD

Based on nationwide data from the Danish Serum Institute and the Danish National Prescription Registry, we retrieved sales statistics for the Danish primary health care sector to calculate 1-year prevalences of prescription users of aspirin or nonaspirin NSAIDs, and to estimate the corresponding proportions of total sales dispensed on prescription.

RESULTS

Both low-dose aspirin and nonaspirin NSAIDs were commonly used in the Danish population between 1999 and 2012, particularly among elderly individuals. The 1-year prevalence of prescribed low-dose aspirin increased throughout the study period, notably among men. Nonaspirin NSAID use was frequent in all age groups above 15 years and showed a female preponderance. Overall, the prevalence of prescribed nonaspirin NSAIDs decreased moderately after 2004, but substantial variation according to NSAID subtype was observed; ibuprofen use increased, use of all newer selective cyclooxygenase-2 inhibitors nearly ceased after 2004, diclofenac use decreased by nearly 50% after 2008, and naproxen use remained stable. As of 2012, the prescribed proportion of individual-level NSAID sales was 92% for low-dose aspirin, 66% for ibuprofen, and 100% for all other NSAIDs.

CONCLUSION

The potential for identifying NSAID use from prescription registries in Denmark is high. Low-dose aspirin and nonaspirin NSAID use varied substantially between 1999 and 2012. Notably, use of cyclooxygenase-2 inhibitors nearly ceased, use of diclofenac decreased markedly, and naproxen use remained unaltered.

Existing data sources for clinical epidemiology: Aarhus University Clinical Trial Candidate Database, Denmark

Denmark is facing a reduction in clinical trial activity as the pharmaceutical industry has moved trials to low-cost emerging economies. Competitiveness in industry-sponsored clinical research depends on speed, quality, and cost. Because Denmark is widely recognized as a region that generates high quality data, an enhanced ability to attract future trials could be achieved if speed can be improved by taking advantage of the comprehensive national and regional registries. A “single point-of-entry” system has been established to support collaboration between hospitals and industry. When assisting industry in early-stage feasibility assessments, potential trial participants are identified by use of registries to shorten the clinical trial startup times. The Aarhus University Clinical Trial Candidate Database consists of encrypted data from the Danish National Registry of Patients allowing an immediate estimation of the number of patients with a specific discharge diagnosis in each hospital department or outpatient specialist clinic in the Central Denmark Region. The free access to health care, thorough monitoring of patients who are in contact with the health service, completeness of registration at the hospital level, and ability to link all databases are competitive advantages in an increasingly complex clinical trial environment.

Thromboprophylaxis only during hospitalisation in fast-track hip and knee arthroplasty, a prospective cohort study

OBJECTIVES

International guidelines recommend thrombosis prophylaxis after total hip arthroplasty (THA) and total knee arthroplasty (TKA) for up to 35 days. However, previous studies often have hospital stays (length of stay; LOS) of 8-12 days and not considering early mobilisation, which may reduce incidence of venous thromboembolic events (VTE). We investigated the incidence of any symptomatic thromboembolic events (TEEs) with only in-hospital prophylaxis if LOS ≤5 days after fast-track THA and TKA.

DESIGN

A prospective descriptive multicentre cohort study in fast-track THA and TKA from February 2010 to December 2011, with complete 90-day follow-up through the Danish National Patient Registry and patient files.

SETTING

6 Danish high-volume centres with a similar standardised fast-track setup, including spinal anaesthesia, opioid-sparing analgesia, early mobilisation, functional discharge criteria and discharge to own home.

PARTICIPANTS

4924 consecutive unselected unilateral primary THA and TKAs in patients ≥18 years with no preoperative use of continuous 'potent' anticoagulative therapy (vitamin K antagonists).

EXPOSURE

Prophylaxis with low-molecular-weight heparin or factor Xa-inhibitors only during hospitalisation when LOS ≤5 days.

OUTCOMES

Incidence of symptomatic TEE-related, VTE-related and VTE-related mortality ≤90 days postoperatively.

RESULTS

LOS ≤5 days and thromboprophylaxis only during hospitalisation occurred in 4659 procedures (94.6% of total). Median LOS and prophylaxis duration was 2 days (IQR 2-3) with 0.84% (95% CI 0.62% to 1.15%) TEE and 0.41% (0.26% to 0.64%) VTE during 90-day follow-up. VTE consisted of five pulmonary embolisms (0.11% (0.05% to 0.25%)) and 14 deep venous thrombosis (0.30% (0.18% to 0.50%)). There were four (0.09% (0.04% to 0.23%)) surgery-related deaths, of which 1 (0.02% (0.00% to 0.12%)) was due to pulmonary embolism, and 6 (0.13% (0.06% to 0.28%)) deaths of unknown causes after discharge.

CONCLUSIONS

The low incidence of TEE and VTE suggests that in-hospital prophylaxis only, is safe in fast-track THA and TKA patients with LOS of ≤5 days. Guidelines on thromboprophylaxis may need reconsideration in fast-track elective surgery.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01557725.

Protocol for a randomised trial on the effect of group education on skin-protective behaviour versus treatment as usual among individuals with newly notified occupational hand eczema - the Prevention of Hand Eczema (PREVEX) Trial

Background

The incidence of occupational hand eczema is approximately 0.32 per 1,000 person years. The burden of the disease is high, as almost 60% has eczema-related sick leave during the first year after notification, and 15% are excluded from the workforce 12 years after disease onset. New treatments and prevention strategies are needed.

Methods/Design

Trial design: The PREVEX trial is a randomised, parallel-group, superiority trial.

Participants: All individuals from the Capital Region of Denmark and Region Zealand with a suspected occupational skin disorder notified to the National Board of Industrial Injuries between June 2012 and December 2013 are invited to participate in the trial. Inclusion criteria are: self-reported hand eczema and informed consent. Exclusion criteria are: age <18 years or >65 years; permanent exclusion from the workforce; inability to understand the Danish language; any serious medical condition; and lack of written informed consent. We plan to randomise 742 participants. Interventions: The experimental intervention is an educational course in skin-protective behaviour and written information about skin care related to the participants' specific occupation. Also, a telephone hotline is available and a subgroup will be offered a work-place visit. The experimental and the control group have access to usual care and treatment. All participants are contacted every eighth week with questions regarding number of days with sick leave or other absence from work. 12 months after randomisation follow-up is completed. Objective: To assesses the effect of an educational course versus treatment as usual in participants with newly notified occupational hand eczema. Randomisation: Participants are centrally randomised according to a computer-generated allocation sequence with a varying block size concealed to investigators. Blinding: It is not possible to blind the participants and investigators, however, data obtained from registers, data entry, statistical analyses, and drawing of conclusions will be blinded. Outcomes: The three co-primary outcomes, assessed at 12 months, are: total number of self-reported days with sick leave; health-related quality of life; and subjective assessment of hand eczema severity. Explorative outcomes are: self-reported eczema-related sick leave, absence from work registered by the DREAM-register and by self-report, risk behaviour, knowledge of skin protection and performance management (self-efficacy; and self-evaluated ability to self-care).

Discussion

The PREVEX trial will be the first individually randomised trial to investigate the benefits and harms of group-based education in patients with newly notified occupational hand eczema.

Trial registration

ClinicalTrials.gov Identifier: NCT01899287

Mental health status and risk of new cardiovascular events or death in patients with myocardial infarction: a population-based cohort study

OBJECTIVE

To examine the association between mental health status after first-time myocardial infarction (MI) and new cardiovascular events or death, taking into account depression and anxiety as well as clinical, sociodemographic and behavioural risk factors.

DESIGN

Population-based cohort study based on questionnaires and nationwide registries. Mental health status was assessed 3 months after MI using the Mental Component Summary score from the Short-Form 12 V.2.

SETTING

Central Denmark Region.

PARTICIPANTS

All patients hospitalised with first-time MI from 1 January 2009 through 31 December 2009 (n=880). The participants were categorised in quartiles according to the level of mental health status (first quartile=lowest mental health status).

MAIN OUTCOME MEASURES

Composite endpoint of new cardiovascular events (MI, heart failure, stroke/transient ischaemic attack) and all-cause mortality.

RESULTS

During 1940 person-years of follow-up, 277 persons experienced a new cardiovascular event or died. The cumulative incidence following 3 years after MI increased consistently with decreasing mental health status and was 15% (95% CI 10.8% to 20.5%) for persons in the fourth quartile, 29.1% (23.5% to 35.6%) in the third quartile, 37.0% (30.9% to 43.9%) in the second quartile, and 47.5% (40.9% to 54.5%) in the first quartile. The HRs were high, even after adjustments for age, sociodemographic characteristics, cardiac disease severity, comorbidity, secondary prophylactic medication, smoking status, physical activity, depression and anxiety (HR3rd quartile 1.90 (95% CI 1.23 to 2.93), HR2nd quartile 2.14 (1.37 to 3.33), HR1st quartile 2.23 (1.35 to 3.68) when using the fourth quartile as reference).

CONCLUSIONS

Low mental health status following first-time MI was independently associated with an increased risk of new cardiovascular events or death. Further research is needed to disentangle the pathways that link mental health status following MI to prognosis and to identify interventions that can improve mental health status and prognosis.

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

OBJECTIVE

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

DESIGN

Cohort study.

PARTICIPANTS

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

SETTING

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

NCT01569139 clinicaltrials.gov.