Anton Pottegård

University of Southern Denmark | SDU · Clinical Pharmacology and Pharmacy, Department of Public Health

Knowledge of patterns of treatment discontinuation in ADHD drug treatment is of importance, both for clinical practice and the study of long-term treatment outcomes. The purpose of this study was to describe early discontinuation of ADHD drug treatment.Using the Danish National Prescription Registry, all first-time users of the ADHD drugs methylphe...

Background Detailed data on real-life utilization of vitamin K-antagonists (VKA) and new oral anticoagulants (NOAC) in atrial fibrillation is sparse.Objectives To describe dynamics of VKA and NOAC use, i.e. 1) how patients moved in and out of, as well as between, use of VKA and NOAC, 2) how patients adhered to treatment; and 3) which type of prescr...

The use of methylphenidate to treat attention-deficit/hyperactivity disorder has risen dramatically in Western countries, and it is increasingly used by adults, including women of childbearing age. Very little is known about potential hazards of in utero exposure to methylphenidate. We conducted this study to estimate the risk of major congenital m...

Aim: Studies of the carcinogenic potential of benzodiazepines and related drugs (BZRD) have been equivocal. A recent study reported a 35% excess cancer risk among users of hypnotics, including benzodiazepines. Method: Using Danish nationwide registers, we conducted a matched case-control study of the association between BZRD and cancer risk. Dur...

The purpose of the study was to characterize the utilization of medication against attention deficit hyperactivity disorder (ADHD) in Denmark between 1995 and 2011 from a national perspective, by using population-based prescription data. National data on drug use in Denmark between 1 January 1995 and 30 September 2011 were extracted from the Regist...

Background Despite its potential value in register-based pharmacoepidemiologic research, recorded information on ‘indication for use’ (INDO) in the Danish National Prescription Registry has rarely been used, likely because of questions about the variable’s validity, which to our knowledge no study has systematically assessed. Methods We extracted...

Understanding the patient perspective is a significant part of the deprescribing process. This study aimed to explore the attitudes of older patients with psychiatric disorders towards deprescribing. A total of 72 of psychiatric outpatients (68% women; median age 76 years) completed the validated Danish version of the revised Patients' Attitudes To...

The aim of this study was to investigate utilisation patterns of prescribed analgesics before, during, and after an exercise therapy and patient education program among patients with knee or hip osteoarthritis. This cohort study is based on data from the nationwide Good Life with osteoarthritis in Denmark (GLA:D®) patient-register linked with natio...

Introduction: Certain clinical events reduce life expectancy and necessitate a reassessment of patient treatment. Objective: To describe medication changes in relation to a cancer diagnosis and the end of life and to highlight challenges and limitations with such descriptions. Methods: From a cohort with all Danish patients with type 2 diabete...

Aims: It is unknown whether the cardiovascular risks associated with the use of non-steroidal anti-inflammatory drugs (NSAIDs) shortly after first-time myocardial infarction (MI) or heart failure (HF) differ between patients continuing and initiating use. Methods and results: Using nationwide health registries, we conducted a cohort study of all...

Background Selective serotonin reuptake inhibitors (SSRIs) are the most frequently prescribed antidepressants in pregnancy. Animal and some clinical studies have suggested potential increases in depression and anxiety following prenatal SSRI exposure, but the extent to which these are driven by the medication remains unclear. We used Danish populat...

Purpose: Database heterogeneity can impact effect estimates. Harmonisation provided by common protocols and common data models (CDMs) can increase the validity of pharmacoepidemiologic research. In a case-study measuring the changes in the safety and effectiveness of stroke prevention therapy after the introduction of direct oral anticoagulants (D...

Purpose: With the increasing utilization of medications worldwide, coupled with the increasing availability of long-term data, there is a growing opportunity and need for robust studies evaluating drug-cancer associations. One methodology of importance in such studies is the application of lag times. Methods: In this narrative review, we discuss...

Objectives To examine valsartan, losartan and irbesartan usage and switching patterns in the USA, UK, Canada and Denmark before and after July 2018, when the first Angiotensin-Receptor-Blocker (ARB) (valsartan) was recalled. Design Retrospective cohort study. Setting USA, Canadian administrative healthcare data, Danish National Prescription Regis...

Aim: Dicloxacillin is used to treat staphylococcal infections and we have previously shown that dicloxacillin is an inducer of cytochrome P450 enzymes (CYPs). Here, we employed a translational approach to investigate the effect of a treatment with dicloxacillin on warfarin efficacy in Danish registries. Furthermore, we assessed dicloxacillin as an...

Background: Repurposing already approved drugs in a cancer setting has gained increasing interest in recent years. Tranexamic acid is an anti-fibrinolytic drug that has recently been suggested as an anti-cancer drug due to its anti-inflammatory and anti-carcinogenic effects in animal studies. In this study, we aimed to investigate the possible mel...

Aims: Drug metabolism might be altered in patients with type 2 diabetes. We aimed to evaluate if initiation of glucose-lowering drugs impacts warfarin efficacy and drug metabolism. Methods: First, we conducted a register-based self-controlled cohort study on Danish and Scottish warfarin users. Warfarin efficacy (international normalized ratio [I...

Background Methotrexate (MTX) use has been suspected of increasing the risk of skin cancer. The aim of this investigation was to examine the association between the use of MTX and the risk of basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC) and cutaneous malignant melanoma (CMM). Methods In a nationwide Danish case–control stud...

Little is known about the combined effect of several risk factors occurring simultaneously, and the perspectives of patients with language barriers or dementia are lacking because these patients are often excluded as research participants. This study aimed at investigating medication safety among older migrants with cognitive disorders who use five...

Background: Observational studies on COVID-19 vaccines compare event rates in vaccinated and unvaccinated person time using Poisson or Cox regression. In Cox regression, the chosen time scale needs to account for the time-varying incidence of SARS-CoV-2 infection and COVID-19 vaccination. Objectives: To quantify bias in person time-based methods...

Aims: Drug-induced diabetes is underreported in conventional drug safety monitoring and may contribute to the increasing incidence of type 2 diabetes. Therefore, we used routinely collected prescription data to screen all commonly used drugs for diabetogenic effects. Methods: Leveraging the Danish nationwide health registries, we used a case-onl...

People suffering from pain constitute a sizeable and heterogeneous patient group. Conventional oral analgesics are considered a cheap and safe first-line treatment. These drugs are used on both a regular and'as needed' basis and are often obtained over-the-counter (OTC). We explored patient-reported patterns of use and adverse effects of analgesics...

Background: Few studies have investigated long-term survival in patients with primary immune thrombocytopenia (pITP). Further, changes in prognosis over the past decades and prognosis of secondary immune thrombocytopenia (sITP) are largely unstudied. Our objectives were to study comorbidity-adjusted prognostic changes and causes of death in chroni...

Background: A previous study in Denmark suggested an increased melanoma risk associated with the use of flecainide. Objective: To study the association between flecainide use and the risk of melanoma and non-melanoma skin cancer in Spain and Denmark. Methods: We conducted a multi-database case–control study in (database/study period) Spain (SIDIAP/...

Importance The direct and indirect implications of the COVID-19 pandemic have been associated with the mental health of children and adolescents, but it is uncertain whether these implications have been associated with changes in prescribing and diagnosis patterns. Objective To examine psychotropic medication use and rates of psychiatric disorders...

Paclitaxel-induced peripheral neuropathy (PIPN) is a barrier to effective cancer treatment and impacts quality of life among cancer patients. We used a translational approach to assess the utility of neurofilament light chain (NFL) as a biomarker of PIPN in a human cell model and in ovarian cancer patients. We measured NFL in medium from human indu...

Aims: The pattern of drugs used to treat type 2 diabetes has changed dramatically over the last one-and-a-half decade. We investigated changes in use patterns in Denmark during 2005 through 2021. Materials and methods: Nationwide population-based drug utilization study based on medical databases covering the Danish population. We assessed incide...

Aims: We describe the distribution of prescribers responsible for opioid initiation and maintenance (general practice, hospital prescribers and other prescribers) in Denmark. Methods: We leveraged data on opioid fills from a 20% sample of all Danes alive during 2000-2021. Results: Overall, general practitioners were responsible for most treatm...

Low-dose aspirin has been hypothesized to prevent cancer risk by inhibiting platelet aggregation. However, the anti-cancer effect of low-dose aspirin has recently been questioned and its effect on breast cancer development remains unclear. The impact of other antiplatelet drugs on breast cancer risk has rarely been evaluated. Thus, this study aimed...

Real‐world evidence (RWE) used for regulatory, payer, and clinical decision‐making requires principled epidemiology in design and analysis, applying methods to minimize confounding given the lack of randomization. One technique to deal with potential confounding is propensity score (PS) analysis, which allows for the adjustment for measured pre‐exp...

Problem: Ambiguity in communication of key study parameters limits the utility of real-world evidence (RWE) studies in healthcare decision-making. Clear communication about data provenance, design, analysis, and implementation is needed. This would facilitate reproducibility, replication in independent data, and assessment of potential sources of b...

Drug metabolism might be altered in patients with type 2 diabetes. We aimed to evaluate if initiation of glucose-lowering drugs impacts warfarin efficacy and drug metabolism. First, we conducted a register-based self-controlled cohort study on Danish and Scottish warfarin users. Warfarin efficacy (International Normalized Ratio (INR)) was compared...

Objectives: Ambiguity in communication of key study parameters limits the utility of real-world evidence (RWE) studies in healthcare decision-making. Clear communication about data provenance, design, analysis, and implementation is needed. This would facilitate reproducibility, replication in independent data, and assessment of potential sources...

Use of benzodiazepines (BZ) and related drugs is subject to considerable debate due to problems with dependency and adverse events. We aimed to describe and compare their use across the Nordic countries. Data on the use of clonazepam, BZ‐sedatives, BZ‐hypnotics, and benzodiazepine‐related drugs([BZRD]) in adults (≥20years) were obtained from nation...

Introduction Hypnotic drug use in children and adolescents is widely debated. Objectives To describe use of hypnotic drugs (melatonin, z-drugs and sedating antihistamines) among 5-24-year-old Scandinavians during 2012 to 2018. Methods Aggregate-level data from public data sources in Sweden, Norway and Denmark. We calculated annual prevalence (use...

Safe and effective use of drugs requires an understanding of metabolism and transport. We identified the 100 most prescribed drugs in six countries and conducted a literature search on in vitro data to assess contribution of Phase I and II enzymes and drug transporters to metabolism and transport. Eighty‐nine of the 100 drugs undergo drug metabolis...

Objective To investigate changes in opioid use after supervised exercise therapy and patient education among knee or hip osteoarthritis patients with chronic opioid use. Method In this cohort study, we linked data from the Good Life with osteoArthritis in Denmark register (GLA:D®; standardised treatment program for osteoarthritis; January 2013 to...

Background: Drug utilization studies are essential to facilitate rational drug use in the society. Aim: In this review, we provide an overview of drug utilization measures that can be used with individual-level drug dispensing data, referencing additional reading on the individual analysis. This is intended to serve as a primer for those new to...

Aims The Danish authorities implemented a differential rollout of the COVID-19 vaccines where individuals at high risk of COVID-19 were prioritized. We describe the temporal uptake and characteristics of COVID-19 vaccine recipients in Denmark. Methods Using nationwide healthcare registries, we identified all Danish residents ⩾5 years of age who re...

We aimed to provide a detailed description of the use of melatonin in Danish children, adolescents, and young adults during 2012–2019. We identified melatonin users 0–24 years of age (n = 43,652; median age 16 years) via the Danish nationwide health registers. Melatonin is a prescription drug in Denmark. The incidence of melatonin use increased fro...

Lack of clinical guidance constitutes a significant barrier to deprescribing. Within Danish clinical guidelines on treatment of dementia, type 2 diabetes, hypertension, and osteoporosis, only limited attention was given to deprescribing. For dementia, type 2 diabetes, and osteoporosis, guidance was primarily focused on when to consider and implemen...

The main tool in drug safety monitoring, spontaneous reporting of adverse effects, is unlikely to detect delayed adverse drug effects including cancer. Hypothesis-free screening studies based on administrative data could improve ongoing drug safety monitoring. Using Danish health registries, we conducted a series of case–control studies by identify...

Background Repeated oral corticosteroid use indicates uncontrolled disease among asthma patients and referral for asthma specialist assessment is recommended. We aimed to describe trends and predictors associated with specialist contacts among young adults with asthma and repeated oral corticosteroid use. Methods Individuals aged 18–45 years with...

Background: Symptoms and treatment of benign prostatic hyperplasia (BPH) or erectile dysfunction (ED) may lead to prostate cancer workup, and patterns of prescriptions before diagnosis may affect findings of pharmacoepidemiological studies. Usage of BPH and ED drugs after diagnosis may be related to prostate cancer treatment. We investigated diffe...

The second‐generation antipsychotic quetiapine is commonly used off‐label for its anxiolytic and hypnotic properties. However, quetiapine is associated with problematic side‐effects. We used Danish Medicinal Product Statistics and a 20% random sample of the Danish population’s prescription fills (2001‐2020) to describe the utilization of quetiapine...

In this review paper, I outline the principles of the cohort as a sampling frame and provide a basic introduction to the cohort study design and the case–control study design, two of the most important designs in the pharmacoepidemiologist's toolbox. Further, I discuss when to prefer one design over the other. The paper is intended as a primer for...

This cohort study used data from Danish registers to assess whether recipients of mRNA COVID-19 vaccines had a higher risk of appendicitis after receiving the shot compared with individuals who did not receive the vaccine.

Objectives To assess the risk of acute and post-acute adverse events after SARS-CoV-2 infection in children and adolescents in Denmark and to evaluate the real world effectiveness of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) among adolescents. Design Cohort study. Setting Nationwide Danish healthcare registers. Participants All Danish people y...

Purpose: To develop the Nordic Multimorbidity Index (NMI), a multimorbidity measure specifically suited to the Nordic health and administrative registry data based on current diagnosis, treatment, and coding practices. Methods: The NMI was developed to predict 5-year mortality in a population-based cohort of randomly sampled Danish residents age...

Aims The Danish authorities implemented a differential rollout of the COVID-19 vaccines where individuals at high risk of COVID-19 were prioritized. We describe the temporal uptake of COVID-19 vaccines and changing characteristics of vaccine recipients in Denmark. Methods Using the Danish national health care registries, we identified all Danish r...

Background and objectives: Aclidinium bromide was approved in the European Union for the treatment of chronic obstructive pulmonary disease (COPD) in adult patients in 2012 and in a fixed-dose combination with formoterol in 2014. We characterised new users of aclidinium, aclidinium/formoterol and other COPD medications and evaluated off-label pres...

Aims There is currently no consensus on whether atrial fibrillation (AF) patients at low risk for stroke (one non-sex-related CHA2DS2-VASc point) should be treated with an oral anticoagulant. Methods and results We conducted a multi-country cohort study in Sweden, Denmark, Norway, and Scotland. In total, 59 076 patients diagnosed with AF at low st...

PurposeTo investigate differences in prescription rates of commonly used drugs among prostate cancer patients and cancer-free comparisons and between patients diagnosed with localized and non-localized disease.Methods We conducted a register-based study including all men aged 50–85 years diagnosed with prostate cancer in Denmark from 1998 to 2015 a...

Background Older migrants with cognitive impairment exposed to polypharmacy constitute a vulnerable group of patients. To our knowledge, evidence on medication safety among this patient group with multiple risk factors is lacking. Objectives To explore the perspectives of health care professionals on medication safety among older migrants with cog...

Objectives To evaluate safety and effectiveness of prophylactic anticoagulation with low molecular weight heparin (LMWH) in individuals hospitalised for COVID-19. Methods Using healthcare records from the capital region of Denmark (March 2020-February 2021) and Karolinska University Hospital in Sweden (February 2020-September 2021), we conducted a...

Long-term oral corticosteroid (OCS) treatment for severe asthma is known to cause significant adverse effects, but knowledge on effects of lower exposures in general asthma populations is limited. We aimed to explore this in a nationwide Danish asthma population. Users of asthma medication aged 18–45 were identified in the Danish nationwide registe...

It is known that younger patients treated with antipsychotics are at increased risk of metabolic events; however, it is unknown how this risk varies according to ethnicity, the class of antipsychotic and the specific product used, and by age group. We conducted a multinational sequence symmetry study in Asian populations (Hong Kong, Japan, Korea, T...

Importance Statin use is common in older persons. Given uncertainties in ongoing benefit, changes in health status, and shifting goals of care and preferences, statin discontinuation may be considered in some older persons, although there is currently little evidence to guide this decision. Objective To evaluate the association between statin disc...

Objectives Emerging evidence supports that PR interval prolongation is associated with increased mortality. However, most previous studies have limited confounder control, and clinical impact in a population of acute ill patients is unknown. The aim of this study was to investigate whether 1-year all-cause mortality was increased in patients presen...

Purpose: Evidence is insufficient to infer whether topical calcineurin inhibitors (TCIs; tacrolimus and pimecrolimus) cause malignancy. The study objective was to estimate the long-term risk of skin cancer and lymphoma associated with topical TCI use in adults and children, separately. Patients and methods: A cohort study in Denmark, Sweden, UK,...

This chapter focuses on the description of key commonalities and distinctions across encounter databases, illustrated with selected examples and supplemented by references to more comprehensive resources in the literature. It includes a dedicated discussion of the considerations faced by researchers when evaluating the appropriateness of a specific...

Background: The Danish National Patient Registry is a major resource for Danish epidemiology. Only a few studies have been conducted to check the validity of the reporting of systemic anticancer treatments. In this study, we assessed this validity for a range of cancer types over a long period of time. Patients and methods: We extracted systemic...

Background Lipid levels in blood have decreased considerably during the past decades in the general population partly due to use of statins. This study aims to investigate the trends in lipid levels between 2001 and 2018 in a statin-free population from primary health care, overall and by sex and age. Methods In a cohort of 634,119 patients from g...

Oral corticosteroids (OCS) are used in asthma management but can cause serious adverse effects. We aimed to investigate the usage trends in a nationwide asthma cohort in Denmark from 1999-2018. Using national registers, we identified young adults (18-45 years) with two or more asthma drug collections within 12 months since the age of 15 years as in...

Background: Studies have suggested increased risks of childhood leukaemia after prenatal exposure to antibiotics, particularly nitrofurantoin. However, these findings may be related to the underlying maternal infection. This multinational study aimed to investigate the association between prenatal nitrofurantoin exposure and childhood leukaemia wh...