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 Knowledge of which medications may lead to acute kidney injury (AKI) is limited, relying mostly on spontaneous reporting in pharmacovigilance systems. We here conducted an exploratory drug-wide association study (DWAS) to screen for associations between dispensed drugs and AKI risk. Methods Using two large Danish and Swedish data linkag...

Background Studying complete hospital care episodes from register data, for instance when assessing length of stay, discharges and readmissions, can cause methodological difficulties due to the lack of a contact linkage identifier. We aimed to develop an algorithm combining sequential attendance contacts in the Danish National Patient Register (DNP...

Background: Patients in temporary stays are typically older individuals with frailty and multimorbidity. However, limited knowledge exists about their medication use. This study aimed to describe prescription drug use among patients in temporary stays in Denmark. Methods: We conducted a drug utilisation study on 11,424 patients in public healthcare...

Background: Temporary stays for patients requiring short-term care outside the home, often following hospital discharge, has gained increasing importance. This study aimed to describe the characteristics and care trajectories of older patients in Danish temporary stays to improve care delivery and patient safety. Methods: We conducted a descriptive...

Background Following the mass recall of valsartan products with nitrosamine impurities in July 2018, the number of patients exposed to these products, the duration of exposure, and the potential for cancer remains unknown. Therefore, we assessed the extent and duration of use of valsartan products with a nitrosamine impurity in the United States, C...

Aim To analyse patterns of glucose‐lowering therapies among people with type 2 diabetes (T2D) in Denmark from 2016 to 2023. Materials and Methods We examined time trends in the clinical profiles of people with T2D who initiated different glucose‐lowering therapy classes for the first time. We furthermore investigated individual‐level treatment tra...

Purpose Long‐term use of hydrochlorothiazide increases the risk of non‐melanoma skin cancer. We aimed to evaluate potential changes in the use of hydrochlorothiazide in Switzerland after a direct healthcare professional communication (DHPC) in November 2018 by Swissmedic. Methods We performed interrupted time‐series analyses using a large Swiss he...

Background: Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have previously been associated with a reduced risk of nephrolithiasis (kidney stones), however, large-scale real-world evidence has been lacking. Objectives: To conduct a multi-national cohort study to evaluate the association between SGLT2i use and reduced risk of nephrolithiasis....

Aim We aimed to assess if dicloxacillin/flucloxacillin reduces the therapeutic efficacy of direct oral anticoagulants (DOACs) and the underlying molecular mechanism. Methods In a randomized, crossover study, we assessed whether dicloxacillin reduces oral absorption of drugs through P‐glycoprotein (P‐gp) during 10 and 28 days of treatment. To study...

OBJECTIVE To determine patient characteristics and dose titration patterns of real-world Wegovy (semaglutide) users. RESEARCH DESIGN AND METHODS We used a population-based cohort study including Danish adults who filled Wegovy prescriptions from 12 December 2022 to 31 December 2023. Outcomes were patient characteristics, prescriber type, and dose...

We aimed to map tasks related to medication management and time consumption in Danish home health care. Nursing staff (n = 30) from five municipalities were followed during a 10-week period and tasks related to medication management, time consumption and information on citizens' medication were registered. A total of 269 courses were registered, in...

Objectives Studies have reported high incidences of stroke in patients hospitalised with SARS-CoV-2, but the impact of disease severity is unexplored. We aimed to estimate the risk of incident ischaemic stroke in SARS-CoV-2 test-positive individuals compared with test-negative individuals stratified by disease severity during acute infection and po...

Objective To determine the added diagnostic value of dipsticks for urinary tract infections (UTI) in acutely hospitalised individuals. Design Prospective population-based cohort study. Setting North Denmark. Participants All adults (≥18 years) examined with dipsticks at emergency departments in North Denmark Region from September 20 through 23 O...

Purpose With decreasing number of hospital beds, more citizens are discharged to temporary care at skilled nursing facilities, requiring increasingly complex care in a non-hospital setting. We mapped challenges related to the transition of citizens from hospital to temporary care at a skilled nursing facility in relation to medication management, r...

Aims Examine whether low-density lipoprotein cholesterol (LDL-C) determination method influences the rate of statin initiation for primary prevention of cardiovascular disease. Methods and Results We conducted a register-based retrospective study in the Region of Southern Denmark. Two hospital-based laboratories in the Region directly measure LDL-...

Real-world evidence (RWE) studies are increasingly used to inform policy and clinical decisions. However, there remain concerns about the credibility and reproducibility of RWE studies. Observational researchers should highlight the level of transparency of their studies by providing a succinct statement addressing study transparency with the publi...

Patients with primary immune thrombocytopenia (ITP) suffer from reduced survival and quality of life, but the underlying reasons for this are largely undescribed. Mental health and the use of psychotropic drugs in ITP is unknown. We investigated the risk of hospital registered mental health events including fatigue and the use of psychotropic drugs...

Purpose Older people have the highest use of antibiotics for acute and chronic urinary tract infection (UTI), despite diagnostic uncertainty and the growing problem of antibiotic resistance. We aim to describe use-patterns of UTI antibiotics two years prior to and following care home admission in Denmark. Methods This was a register-based nationwi...

Purpose A surge in the use of semaglutide injection (Ozempic®) approved to treat type 2 diabetes (T2D) has led to a global supply shortage. We investigated contemporary user rates and clinical characteristics of semaglutide (Ozempic®) users in Denmark, and the extent of “off-label” prescribing for weight loss. Patients and Methods Nationwide popul...

Being able to critically evaluate modern cohort studies is important when being presented with claims based on observational evidence. In this review article, key aspects of the cohort design are presented using an example of a cohort study investigating the association between the use of SGLT2 inhibitors and gout. We describe the active comparator...

Purpose This study aimed to systematically evaluate the validity of variables related to pregnancy, delivery, and key characteristics of the infant in the Danish National Patient Register using maternal medical records as the reference standard. Patients and Methods We reviewed medical records of 1264 women giving birth in the Region of Southern D...

The case-control design is one of the key designs used in observational research. In this review, we discuss common pitfalls of case-control studies and describe how case-control studies can be critically evaluated. We further assert that a well-conducted case-control study provides the same results, precision, and level of evidence as a correspond...

Corticosteroids remain the first‐line treatment of immune thrombocytopenia (ITP), but increase the risk of osteoporosis and fractures. Bisphosphonates are used for the treatment of osteoporosis, but their usage among patients with ITP has not been systemically described. We investigated the risk of fractures and the use of bisphosphonates in adult...

Objective Patients receiving immunosuppressives have been excluded from trials for SARS-CoV-2 vaccine efficacy. Investigation of immunosuppressants’ impact on effectiveness of vaccines, particularly in patients with immune-mediated inflammatory diseases (IMID), is therefore required. Design We performed a nationwide cohort study to assess the risk...

Background: Following the mass recall of valsartan products with nitrosamine impurities in July 2018, the number of patients exposed to these valsartan products, the duration of exposure, and the potential for cancer remains unknown. Therefore, we assessed the extent and duration of use of valsartan products with a nitrosamine impurity in the US, C...

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...

Aims 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...

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...

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 [INR])...

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...

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 treatment in...

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...