Kasper Søltoft Larsen

Satisfying convex risk limits by trading

Abstract.A random variable, representing the final position of a trading strategy, is deemed acceptable if under each of a variety of probability measures its expectation dominates a floor associated with the measure. The set of random variables representing pre-final positions from which it is possible to trade to final acceptability is characterized. In particular, the set of initial capitals from which one can trade to final acceptability is shown to be a closed half-line

Impact of Urate Level on Cardiovascular Risk in Allopurinol Treated Patients. A Nested Case-Control Study.

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Randomized clinical trial: the impact of gastrointestinal risk factor screening and prophylactic proton pump inhibitor therapy in patients receiving dual antiplatelet therapy

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Modelling of endpoint postponement for all-cause mortality in statin trials

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Impact of urate level on cardiovascular risk in allopurinol-treated patients: A nested case-control study

Background Gout gives rise to increased risk of cardiovascular events. Gout attacks can be effectively prevented with urate lowering drugs, and allopurinol potentially reduces cardiovascular risk. What target level of urate is required to reduce cardiovascular risk is not known. Objectives To investigate the effect of achieving target plasma urate with allopurinol on cardiovascular outcomes in a case-control study nested within long-term users of allopurinol. Methods We identified long-term users of allopurinol in Funen County, Denmark. Among these, we identified all cases of cardiovascular events and sampled 4 controls to each case from the same population. The cases and controls were compared with respect to whether they reached a urate target below 0.36 mmol/l on allopurinol. The derived odds ratios were controlled for potential confounders available from data on prescriptions, laboratory values and in- and outpatient contacts. Results No association between treatment-to-target urate level and cardiovascular events were found (adjusted odds ratio of 1.01, 95% confidence interval 0.79–1.28). No significant effect was seen in any subgroup defined by age, gender, renal function, allopurinol dose or the achieved urate level. Overall, the doses of allopurinol used in this study were low (mean ≈ 140 mg/day). Conclusion We were unable to demonstrate a link between achieved urate level in patients treated with allopurinol and risk of cardiovascular events. Possible explanations include that allopurinol doses higher than those used in this study are required to achieve cardiovascular risk reduction or that the cardiovascular effect of allopurinol is not mediated through low urate levels. It remains to be seen whether allopurinol has a dose-response relationship with cardiovascular events at higher doses.

Effect of Allopurinol on Cardiovascular Outcomes in Hyperuricemic Patients: A Cohort Study.

Objectives To describe the development of acronym use across five major medical specialties and to evaluate the technical and aesthetic quality of the acronyms. Design Acronyms obtained through a literature search of Pubmed.gov followed by a standardised assessment of acronym quality (BEAUTY and CHEATING criteria). Participants Randomised controlled trials within psychiatry, rheumatology, pulmonary medicine, endocrinology, and cardiology published between 2000 and 2012. Main outcome measures Prevalence proportion of acronyms and composite quality score for acronyms over time. Results 14 965 publications were identified, of which 18.3% (n=2737) contained an acronym in the title. Acronym use was more common among cardiological studies than among the other four medical specialties (40% v 8-15% in 2012, P<0.001). Except for within cardiology, the prevalence of acronyms increased over time, with the average prevalence proportion among the remaining four specialties increasing from 4.0% to 12.4% from 2000 to 2012 (P<0.001). The median combined acronym quality score decreased significantly over the study period (P<0.001), from a median 9.25 in 2000 to 5.50 in 2012. Conclusion From 2000 to 2012 the prevalence of acronyms in trial reports increased, coinciding with a substantial decrease in the technical and aesthetic quality of the acronyms. Strict enforcement of current guidelines on acronym construction by journal editors is necessary to ensure the proper use of acronyms in the future.

Is urate crystal precipitation a predictor of cardiovascular risk in hyperuricemic patients? A Danish cohort study

Objective Dual antiplatelet therapy reduces the risk of ischemic complications after acute coronary syndrome, but increases the risk of bleeding including upper gastrointestinal bleeding (UGIB). The aim of this study was to examine the effect of screening for risk of UGIB and prophylactic proton pump inhibitor (PPI) treatment in dual-antiplatelet-treated patients at risk of UGIB and to assess the significance of dual antiplatelet therapy compliance for cardiovascular events. Patients and methods In a register-based randomized-controlled trial, 2009 patients were included at the time of first percutaneous coronary intervention and randomized to either screening or control. Screened high-risk patients were prescribed pantoprazole 40 mg during the 1-year after percutaneous coronary intervention. Results The incidence of UGIB was 0.8 versus 1.3% in screened patients and controls, respectively (P=0.381). Significantly fewer screened patients (5.4%) than controls (8.0%) underwent upper gastrointestinal endoscopy (P=0.026). Screened patients (2.9%) had significantly fewer events of unstable angina pectoris than controls (4.7%) (P=0.036) and a higher compliance to dual antiplatelet therapy (88.3 vs. 85.0%) (P=0.035), but no statistically difference was observed in the incidences of myocardial infarction and all-cause mortality (1.0 vs. 1.5%) (P=0.422). Conclusion Screening for risk factors for UGIB and subsequent prophylactic PPI treatment did not significantly reduce the incidence of UGIB. Prescription of PPI was associated with a higher compliance with dual antiplatelet therapy and decreases the risk of recurrent cardiovascular events.

Use of exenatide and liraglutide in Denmark: a drug utilization study

Background: Sudden discontinuation of some antihypertensive agents such as beta-blockers and centrally acting antihypertensive agents are associated with increased risk of acute coronary events. Objectives: The aim of this study was to assess the association between discontinuation of different antihypertensive agents and the risk of acute myocardial infarction (AMI). Methods: A nested case control study was performed in a cohort of antihypertensive drug users from the Utrecht Cardiovascular Pharmacogenetics (UCP) database. Within this cohort, patients who were hospitalized for first AMI were considered cases. Cases were matched (1 up to 4) to controls at the same AMI date (index date). Antihypertensive users were defined as current users if the index date fell within prescribed duration or as stoppers if this date fell outside the prescribed duration. According to recency of stopping, stoppers were divided into recent stoppers (≤90 days), intermediate-term stoppers (91-180 days), and longterm stoppers (>180 days). The study included only antihypertensive users who were specifically current users or stoppers of one antihypertensive agent. Logistic regression analysis was used to assess the association between the discontinuation of antihypertensive agents and the risk of AMI and to control for confounding. Results: We included 1245 cases and 4994 controls in our analysis. The risk of AMI was significantly increased with all stoppers of beta-blockers (adjusted OR: 1.54, 95%CI (1.25-1.90)), calcium channel blockers (CCBs) (adjusted OR: 2.25, 95%CI (1.53- 3.30)), and diuretics (adjusted OR: 1.76, 95%CI (1.24-2.48)) compared with current users. Moreover, the risk of AMI was significantly increased for longterm stoppers (beta-blockers, CCBs, angiotensinconverting enzyme inhibitors, and diuretics) and intermediate- term stoppers (beta-blockers and CCBs) versus current users. There was no difference in AMI risk between recent stoppers of antihypertensive agents versus current users. Conclusions: Discontinuation of antihypertensive agents increases the risk of AMI after more than 90 days of stopping. Adherence to antihypertensive agents plays an important role in reducing the risk of AMI in patients with hypertension.Background: It has been reported that patients with type 1 diabetes (T1DM) have a decreased lung function. Studies on the association of T1DM and asthma in children show controversial results. Objectives: The aim of this study was to quantify asthma medication use in children and adolescents with and without (reference cohort) T1DM 5 years before and after the onset of diabetes. Methods: A population-based cohort study was conducted in the Dutch PHARMO Record Linkage System. All children (1. Modelling of Endpoint Postponement for All-Cause Mortality in Statin Trials Morten Rix Hansen, Anton Pottegård, Asbjørn Hróbjartsson, Per Damkier, René D Christensen, Kasper Søltoft Larsen, Malene EL Kristensen, Palle M Christensen, Jesper Hallas. Clinical Pharmacology, University of Southern Denmark, Odense, Denmark; Department of Clinical Chemistry and Pharmacology, Odense University Hospital, Odense, Denmark; The Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark; Research Unit for General Practice, University of Southern Denmark, Odense, Denmark. Background: The average postponement of the outcome event has been proposed as a novel method to present the magnitude of effect for preventive medications. This measure has been shown to have better agreement with patient preferences than conventional outcomemeasures, including the “number needed to treat” (NNT), possibly because it is more intuitively understood. For some interventions, it may also provide a better theoretical frame for how benefit is distributed among participants than the NNT measure. The aim of this study was to present a novel method for modelling endpoint postponement (EP) from trial data and compare it with the usual approach of measuring the area between survival curves. We also present a formalized meta-analysis of modelled EP for all-cause mortality in statin trials. Methods: We identified 17 placebo-controlled statin trials that fulfilled our inclusion criteria. Eleven of these presented Kaplan–Meier curves for all-cause mortality. Average EP was calculated as the area between Kaplan–Meier curves by counting pixels on magnified prints for these 11 trials. The modelled EP was computed for all trials on the basis of (1) hazard ratio, relative risk or odds ratio; (2) the cumulative event rate in the untreated group; and (3) the trial’s running time. The underlying assumption was that the mortality was reasonably stable within the trials’ running time. The modelled EP was subjected to a meta-analysis, using inverse variance weighting in a random effect model. Results: EPswere generally small for estimates based on pixel-counting, 10 and 27days for trials both primary and secondary intervention that typically ran over 1.9– 6.1years. The modelled EPs varied between 2 and 34days. The difference between modeled EP and EP based on pixel-counting was between 8 and 12days. The results of the meta-analyses will be presented at the meeting. Conclusions: Based on these trial data, statin treatment results in a surprisingly small gain in average survival. Our modelled EP estimates agreed reasonably with EPs based on pixel-counting. The modeled EP is amenable to meta-analyses and may be a useful approach to presenting the benefit of preventive treatment. 2. Permanent User Bias in Case–Crossover Studies in Pharmacoepidemiology Jesper Hallas, Shirley V. Wang, Joshua J. Gagne, Sebastian Schneeweiss, Anton Pottegård. Clinical Pharmacology, University of Southern Denmark, Odense C, Denmark; Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA. Background: In pharmacoepidemiology, the case– crossover design is based on cases that have contrasting drug exposure at the time of an event and at a reference time in the past. If the drug in question should be taken permanently, only certain exposure patterns will occur. These patients cannot be unexposed at the event time and exposed at the reference time, while the opposite pattern can occur if the drug was initiated recently. The resulting odds ratio (OR) would thus be biased upward. As many drugs have a subpopulation of permanent users, this bias might pervade many case–crossover analyses of drug effects. Objectives: The aims of this study were to demonstrate this “permanent user bias” and to evaluate whether it can be remedied by including a control group (case–time–control design). Methods: Using nationwide Danish data resources, we conducted case–crossover and case–time–control analyses for combinations of three exposures that are

Pharmacoepidemiological aspects of allopurinol use on cardiovascular diseases among hyperuricemic individuals

Background: Sudden discontinuation of some antihypertensive agents such as beta-blockers and centrally acting antihypertensive agents are associated with increased risk of acute coronary events. Objectives: The aim of this study was to assess the association between discontinuation of different antihypertensive agents and the risk of acute myocardial infarction (AMI). Methods: A nested case control study was performed in a cohort of antihypertensive drug users from the Utrecht Cardiovascular Pharmacogenetics (UCP) database. Within this cohort, patients who were hospitalized for first AMI were considered cases. Cases were matched (1 up to 4) to controls at the same AMI date (index date). Antihypertensive users were defined as current users if the index date fell within prescribed duration or as stoppers if this date fell outside the prescribed duration. According to recency of stopping, stoppers were divided into recent stoppers (≤90 days), intermediate-term stoppers (91-180 days), and longterm stoppers (>180 days). The study included only antihypertensive users who were specifically current users or stoppers of one antihypertensive agent. Logistic regression analysis was used to assess the association between the discontinuation of antihypertensive agents and the risk of AMI and to control for confounding. Results: We included 1245 cases and 4994 controls in our analysis. The risk of AMI was significantly increased with all stoppers of beta-blockers (adjusted OR: 1.54, 95%CI (1.25-1.90)), calcium channel blockers (CCBs) (adjusted OR: 2.25, 95%CI (1.53- 3.30)), and diuretics (adjusted OR: 1.76, 95%CI (1.24-2.48)) compared with current users. Moreover, the risk of AMI was significantly increased for longterm stoppers (beta-blockers, CCBs, angiotensinconverting enzyme inhibitors, and diuretics) and intermediate- term stoppers (beta-blockers and CCBs) versus current users. There was no difference in AMI risk between recent stoppers of antihypertensive agents versus current users. Conclusions: Discontinuation of antihypertensive agents increases the risk of AMI after more than 90 days of stopping. Adherence to antihypertensive agents plays an important role in reducing the risk of AMI in patients with hypertension.Background: It has been reported that patients with type 1 diabetes (T1DM) have a decreased lung function. Studies on the association of T1DM and asthma in children show controversial results. Objectives: The aim of this study was to quantify asthma medication use in children and adolescents with and without (reference cohort) T1DM 5 years before and after the onset of diabetes. Methods: A population-based cohort study was conducted in the Dutch PHARMO Record Linkage System. All children (1. Modelling of Endpoint Postponement for All-Cause Mortality in Statin Trials Morten Rix Hansen, Anton Pottegård, Asbjørn Hróbjartsson, Per Damkier, René D Christensen, Kasper Søltoft Larsen, Malene EL Kristensen, Palle M Christensen, Jesper Hallas. Clinical Pharmacology, University of Southern Denmark, Odense, Denmark; Department of Clinical Chemistry and Pharmacology, Odense University Hospital, Odense, Denmark; The Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark; Research Unit for General Practice, University of Southern Denmark, Odense, Denmark. Background: The average postponement of the outcome event has been proposed as a novel method to present the magnitude of effect for preventive medications. This measure has been shown to have better agreement with patient preferences than conventional outcomemeasures, including the “number needed to treat” (NNT), possibly because it is more intuitively understood. For some interventions, it may also provide a better theoretical frame for how benefit is distributed among participants than the NNT measure. The aim of this study was to present a novel method for modelling endpoint postponement (EP) from trial data and compare it with the usual approach of measuring the area between survival curves. We also present a formalized meta-analysis of modelled EP for all-cause mortality in statin trials. Methods: We identified 17 placebo-controlled statin trials that fulfilled our inclusion criteria. Eleven of these presented Kaplan–Meier curves for all-cause mortality. Average EP was calculated as the area between Kaplan–Meier curves by counting pixels on magnified prints for these 11 trials. The modelled EP was computed for all trials on the basis of (1) hazard ratio, relative risk or odds ratio; (2) the cumulative event rate in the untreated group; and (3) the trial’s running time. The underlying assumption was that the mortality was reasonably stable within the trials’ running time. The modelled EP was subjected to a meta-analysis, using inverse variance weighting in a random effect model. Results: EPswere generally small for estimates based on pixel-counting, 10 and 27days for trials both primary and secondary intervention that typically ran over 1.9– 6.1years. The modelled EPs varied between 2 and 34days. The difference between modeled EP and EP based on pixel-counting was between 8 and 12days. The results of the meta-analyses will be presented at the meeting. Conclusions: Based on these trial data, statin treatment results in a surprisingly small gain in average survival. Our modelled EP estimates agreed reasonably with EPs based on pixel-counting. The modeled EP is amenable to meta-analyses and may be a useful approach to presenting the benefit of preventive treatment. 2. Permanent User Bias in Case–Crossover Studies in Pharmacoepidemiology Jesper Hallas, Shirley V. Wang, Joshua J. Gagne, Sebastian Schneeweiss, Anton Pottegård. Clinical Pharmacology, University of Southern Denmark, Odense C, Denmark; Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA. Background: In pharmacoepidemiology, the case– crossover design is based on cases that have contrasting drug exposure at the time of an event and at a reference time in the past. If the drug in question should be taken permanently, only certain exposure patterns will occur. These patients cannot be unexposed at the event time and exposed at the reference time, while the opposite pattern can occur if the drug was initiated recently. The resulting odds ratio (OR) would thus be biased upward. As many drugs have a subpopulation of permanent users, this bias might pervade many case–crossover analyses of drug effects. Objectives: The aims of this study were to demonstrate this “permanent user bias” and to evaluate whether it can be remedied by including a control group (case–time–control design). Methods: Using nationwide Danish data resources, we conducted case–crossover and case–time–control analyses for combinations of three exposures that are