Control yourself: ISPE-endorsed guidance in the application of self-controlled study designs in pharmacoepidemiology

Thinking Three-Dimensionally: A Self- and Externally-Controlled Approach to Screening for Drug-Drug-Drug Interactions Among High-Risk Populations

The global rise in polypharmacy has increased both the necessity and complexity of drug-drug interaction (DDI) assessments, given the growing potential for interactions involving more than two drugs. Leveraging large-scale healthcare claims data, we piloted a semi-automated, high-throughput case-crossover-based approach for drug-drug-drug interaction (3DI) screening. Cases were direct-acting oral anticoagulant (DOAC) users with either a major bleeding event during ongoing dispensings for potentially interacting, enzyme-inhibiting antihypertensive drugs (AHDs) (Study 1), or a thromboembolic event during ongoing dispensings for potentially interacting, enzyme-inducing antiseizure medications (ASMs) (Study 2). 3DI detection was based on screening for additional drug exposures that served as acute outcome triggers. To mitigate direct effects and confounding by concomitant drugs, self-controlled estimates were adjusted using negative cases (external "control" DOAC users with the same outcomes but co-dispensings for non-interacting AHDs or ASMs). Signal thresholds were set based on P-values and false discovery rate q-values to address multiple comparisons. Study 1: 285 drugs were examined among 3,306 episodes. Self-controlled assessments with q-value thresholds yielded 9 3DI signals (cases) and 40 DDI signals (negative cases). External adjustment generated 10 3DI signals from the P-value threshold and no signals from the q-value threshold. Study 2: 126 drugs were examined among 604 episodes. Assessments with P-value thresholds yielded 3 3DI and 26 DDI signals following self-control, as well as 4 3DI signals following adjustment. No 3DI signals met the q-value threshold. The presented self- and externally-controlled approach aimed to advance paradigms for real-world higher order drug interaction screening among high-susceptibility populations with pre-existent DDI risk.

Cholinesterase inhibitors and non-steroidal anti-inflammatory drugs and the risk of peptic ulcers: A self-controlled study

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) should be used with caution in adults aged 65 years and older. Their gastrointestinal adverse event risk might be further reinforced when using concomitant cholinesterase inhibitors (ChEIs). We aimed to investigate the association between NSAIDs and ChEI use and the risk of peptic ulcers in adults aged 65 years and older.

METHODS

Register-based self-controlled case series study including adults ≥65 years with a new prescription of ChEIs and NSAIDs, diagnosed with incident peptic ulcer in Sweden, 2007-2020. We identified persons from the Total Population Register individually linked to several nationwide registers. We estimated the incidence rate ratio (IRR) of peptic ulcer with a conditional Poisson regression model for four mutually exclusive risk periods: use of ChEIs, NSAIDs, and the combination of ChEIs and NSAIDs, compared with the non-treatment in the same individual. Risk periods were identified based on the prescribed daily dose, extracted via a text-parsing algorithm, and a 30-day grace period.

RESULTS

Of 70,060 individuals initiating both ChEIs and NSAIDs, we identified 1500 persons with peptic ulcer (median age at peptic ulcer 80 years), of whom 58% were females. Compared with the non-treatment periods, the risk of peptic ulcer substantially increased for the combination of ChEIs and NSAIDs (IRR: 9.0, [6.8-11.8]), more than for NSAIDs alone (5.2, [4.4-6.0]). No increased risks were found for the use of ChEIs alone (1.0, [0.9-1.2]).

DISCUSSION

We found that the risk of peptic ulcer associated with the concomitant use of NSAIDs and ChEIs was over and beyond the risk associated with NSAIDs alone. Our results underscore the importance of carefully considering the risk of peptic ulcers when co-prescribing NSAIDs and ChEIs to adults aged 65 years and older.

Immune thrombocytopenic purpura and Guillain-Barré syndrome after 23-valent pneumococcal polysaccharide vaccination in Japan: The vaccine effectiveness, networking, and universal safety (VENUS) study

BACKGROUND

To address the lack of an active vaccine safety surveillance system in Japan, the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study was initiated in 2021 as a pilot system using existing health insurance claims data and vaccination records.

METHODS

This study evaluated the value of the VENUS study by assessing the incidence of immune thrombocytopenic purpura (ITP) and Guillain-Barré syndrome (GBS) following vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) using a self-controlled case series (SCCS) design.

RESULTS

Incidence rate ratios for ITP during 28-day and 42-day risk periods were 0.89 (95% confidence interval [CI], 0.12-6.4), and 0.58 (95% CI, 0.081-4.2), respectively. Neither was statistically significant. Incidence rate ratios could not be estimated for GBS due to the limited sample size.

CONCLUSION

The VENUS study can provide valuable insights to facilitate the establishment of an advanced vaccine monitoring system in Japan.

Self-controlled Case Series Study for Acute Kidney Injury after Starting Proton Pump Inhibitors or Potassium-Competitive Acid Blocker in Patients with Cancer Using a Large Claims Database

To investigate the risk of acute kidney injury (AKI) in patients with cancer following the initiation of proton pump inhibitors (PPIs) and potassium-competitive acid blocker (PCAB), considering sex and anti-cancer drug use. We conducted a self-controlled case-series study using the Japan Medical Data Center claims data from 12422 patients with cancer who were prescribed PPIs or PCAB between January 2017 and December 2019. Considering the timing of PPI or PCAB, control period (days -120 to -1), risk period 1 (days 0 to +30), and risk period 2 (days +31 to +365) were defined. To assess the incidence rate ratio (IRR) and 95% confidence interval (CI) as the risk ratio, we adjusted for anti-cancer drugs to assess the risk of AKI. Additionally, we also examined sex differences to identify the risk of AKI. AKI was observed in risk period 1 [2.05 (1.12-3.72), p = 0.0192], but a slight reduction was noted in risk period 2 [0.60 (0.36-1.00), p = 0.0481]. A sex-specific increase in the risk of AKI was observed only in males during risk period 1 [2.18 (1.10-4.32), p = 0.0260], with a reduction in risk period 2 [0.48 (0.26-0.89), p = 0.0200]. We identified an increased risk of AKI in patients with cancer starting PPIs or PCAB particularly in males within 30 d after PPI or PCAB initiation, emphasizing the need for vigilant monitoring and management of AKI in this patient population.

Effect of incarceration and opioid agonist treatment transitions on risk of hospitalisation with injection drug use-associated bacterial infections: A self-controlled case series in New South Wales, Australia

BACKGROUND

Transitional times in opioid use, such as release from prison and discontinuation of opioid agonist treatment (OAT), are associated with health harms due to changing drug consumption practices and limited access to health and social supports. Using a self-controlled (within-person) study design, we aimed to understand if these transitions increase risks of injection drug use-associated bacterial infections.

METHODS

We performed a self-controlled case series among a cohort of people with opioid use disorder (who had all previously accessed OAT) in New South Wales, Australia, 2001-2018. The outcome was hospitalisation with injecting-related bacterial infections. We divided participants' observed days into time windows related to incarceration and OAT receipt. We compared hospitalization rates during focal (exposure) windows and referent (control) windows (i.e., 5-52 weeks continuously not incarcerated or continuously receiving OAT). We estimated adjusted incidence rate ratios (aIRR) using conditional logistic regression, adjusted for time-varying confounders.

RESULTS

There were 7590 participants who experienced hospitalisation with injecting-related bacterial infections (35% female; median age 38 years; 78% hospitalised with skin and soft-tissue infections). Risk for injecting-related bacterial infections was elevated for two weeks following release from prison (aIRR 1.45; 95%CI 1.22-1.72). Risk was increased during two weeks before (aIRR 1.89; 95%CI 1.59-2.25) and after (aIRR 1.91; 95%CI 1.54-2.36) discontinuation of OAT, and during two weeks before (aIRR 3.63; 95%CI 3.13-4.22) and after (aIRR 2.52; 95%CI 2.09-3.04) OAT initiation.

CONCLUSION

Risk of injecting-related bacterial infections varies greatly within-individuals over time. Risk is raised immediately after prison release, and around initiation and discontinuation of OAT. Social contextual factors likely contribute to excess risks at transitions in incarceration and OAT exposure.

Association between recently raised anticholinergic burden and risk of acute cardiovascular events: nationwide case-case-time-control study

OBJECTIVE

To evaluate the association between recently raised anticholinergic burden and risk of acute cardiovascular events in older adults.

DESIGN

Case-case-time-control study (ie, incorporating a case crossover design and a control crossover design consisting of future cases).

SETTING

Taiwan's National Health Insurance Research Database.

PARTICIPANTS

317 446 adults aged ≥65 who were admitted to hospital because of an incident acute cardiovascular event between 2011 and 2018. Acute cardiovascular events included myocardial infarction, strokes, arrhythmias, conduction disorders, and cardiovascular death.

MAIN OUTCOME MEASURES

The anticholinergic burden was measured for each participant by adding up the anticholinergic scores for individual drugs using the Anticholinergic Cognitive Burden Scale. Scores were classified into three levels (0 points, 1-2 points, and ≥3 points). For each participant, anticholinergic burden levels during hazard periods (day -1 to -30 before the cardiovascular event) were compared with randomly selected 30 day reference periods (ie, periods between days -61 and -180). Conditional logistic regression determined odds ratios with 95% confidence intervals to evaluate the association between acute cardiovascular events and recently raised anticholinergic burden.

RESULTS

The crossover analyses included 248 579 current cases. Participants' average age on the index date was 78.4 years (standard deviation 0.01), and 53.4% were men. The most frequently prescribed drugs with anticholinergic activity were antihistamines (68.9%), gastrointestinal antispasmodics (40.9%), and diuretics (33.8%). Among patients with varying levels of anticholinergic burden in different periods, more patients carried higher levels of anticholinergic burden during hazard periods than during reference periods. For example, 17 603 current cases had 1-2 points of anticholinergic burden in the hazard period with 0 points in the reference period, while 8507 current cases had 0 points in the hazard period and 1-2 points in the reference period. In the comparison of 1-2 points versus 0 points of anticholinergic burden, the odds ratio was 1.86 (95% confidence interval 1.83 to 1.90) in the case crossover analysis and 1.35 (1.33 to 1.38) in the control crossover analysis, which yielded a case-case-time-control odds ratio of 1.38 (1.34 to 1.42). Similar results were found in the comparison of ≥3 versus 0 points (2.03, 1.98 to 2.09) and ≥3 versus 1-2 points (1.48, 1.44 to 1.52). The findings remained consistent throughout a series of sensitivity analyses (eg, cut-off points for anticholinergic burden categories were redefined and different scales were used to measure anticholinergic burden).

CONCLUSIONS

An association was found between recently raised anticholinergic burden and increased risk of acute cardiovascular events. Furthermore, a greater increase in anticholinergic burden was associated with a higher risk of acute cardiovascular events.

Evaluating the use of methods to mitigate bias from non-transient medications in the case-crossover design: A systematic review

PURPOSE

The case-crossover design is a self-controlled study design used to compare exposure immediately preceding an event occurrence with exposure in earlier control periods. The design is most suitable for transient exposures in order to avoid biases that can be problematic when using the case-crossover design for non-transient (i.e., chronic) exposures. Our goal was to conduct a systematic review of case-crossover studies and its variants (case-time-control and case-case-time-control) in order to compare design and analysis choices by medication type.

METHODS

We conducted a systematic search to identify recent case-crossover, case-time-control, and case-case-time-control studies focused on medication exposures. Articles indexed in MEDLINE and EMBASE using these study designs that were published between January 2015 and December 2021 in the English language were identified. Reviews, methodological studies, commentaries, articles without medications as the exposure of interest, and articles with no available full text were excluded. Study characteristics including study design, outcome, risk window, control window, reporting of discordant pairs, and inclusion of sensitivity analyses were summarized overall and by medication type. We further evaluated the implementation of recommended methods to account for biases introduced by non-transient exposures among articles that used the case-crossover design on a non-transient exposure.

RESULTS

Of the 2036 articles initially identified, 114 articles were included. The case-crossover was the most common study design (88%), followed by the case-time-control (17%), and case-case-time-control (3%). Fifty-three percent of the articles included only transient medications, 35% included only non-transient medications, and 12% included both. Across years, the proportion of case-crossover articles evaluating a non-transient medication ranged from 30% in 2018 to 69% in 2017. We found that 41% of the articles that evaluated a non-transient medication did not apply any of the recommended methods to account for biases and more than half of which were conducted by authors with no previous publication history of case-crossover studies.

CONCLUSION

Using the case-crossover design to evaluate a non-transient medication remains common in pharmacoepidemiology. Researchers should apply appropriate design and analysis choices when opting to use a case-crossover design with non-transient medication exposures.

A Road Map for Peer Review of Real-World Evidence Studies on Safety and Effectiveness of Treatments

The growing acceptance of real-world evidence (RWE) in clinical and regulatory decision-making, coupled with increasing availability of health care data and advances in automated analytic approaches, has contributed to a marked expansion of RWE studies of diabetes and other diseases. However, a recent spate of high-profile retractions highlights the need for improvements in the conduct of RWE research as well as in the associated peer review and editorial processes. We review best pharmacoepidemiologic practices and common pitfalls regarding design, measurement, analysis, data validity, appropriateness, and generalizability of RWE studies. To enhance RWE study assessments, we propose that journal editors require 1) study authors to complete RECORD-PE, a reporting guideline for pharmacoepidemiological studies on routinely collected data, 2) availability of predetermined study protocols and analysis plans, 3) inclusion of pharmacoepidemiologists on the peer review team, and 4) provision of detail on data provenance, characterization, and custodianship to facilitate assessment of the data source. We recognize that none of these steps guarantees a high-quality research study. Collectively, however, they permit an informed assessment of whether the study was adequately designed and conducted and whether the data source used was fit for purpose.

Heart Failure Following Anti-Inflammatory Medications in Patients With Type 2 Diabetes Mellitus

BACKGROUND

Fluid retention and endothelial dysfunction have been related to use of nonsteroidal anti-inflammatory drugs (NSAIDs), and type 2 diabetes mellitus (T2DM) has been linked to both a decline in kidney function and subclinical cardiomyopathy.

OBJECTIVES

The authors hypothesized that short-term use of NSAIDs could lead to subsequent development of incident heart failure (HF) in patients with T2DM.

METHODS

Using nationwide Danish registers, we identified patients diagnosed with T2DM during 1998 to 2021 and included patients without previous HF, rheumatic disease, or use of NSAIDs 120 days before diagnosis. Associations between NSAIDs and first-time HF hospitalization were investigated using a case-crossover design with 28-day exposure windows, and ORs with 95% CIs were reported.

RESULTS

Included were 331,189 patients with T2DM: 44.2% female, median age of 62 years (IQR: 52-71 years); 23,308 patients were hospitalized with HF during follow-up, and 16% of patients claimed at least 1 NSAID prescription within 1 year. Short-term use of NSAIDs was associated with increased risk of HF hospitalization (OR: 1.43; 95% CI: 1.27-1.63), most notably in subgroups with age ≥80 years (OR: 1.78; 95% CI: 1.39-2.28), elevated hemoglobin (Hb) A1c levels treated with 0 to 1 antidiabetic drug (OR: 1.68; 95% CI: 1.00-2.88), and without previous use of NSAIDs (OR: 2.71; 95% CI: 1.78-4.23).

CONCLUSIONS

NSAIDs were widely used and were associated with an increased risk of first-time HF hospitalization in patients with T2DM. Patients with advanced age, elevated HbA1c levels, and new users of NSAID seemed more susceptible. These findings could guide physicians prescribing NSAIDs.

Association between prescribed opioid dose and risk of motor vehicle crashes

ABSTRACT

Opioid-involved motor vehicle traffic fatalities have increased over the past 2 decades. However, the extent to which prescribed opioids increase the risk of motor vehicle crashes remains uncertain. This study used real-world healthcare claims data to examine the association between prescription opioid dose and motor vehicle crash risk. Using nationwide US commercial insurance claims data for 2010 to 2018, we identified 772,404 adults who received incident, noncancer opioid therapy. We examined associations between daily prescription opioid dose, calculated in morphine milligram equivalents (MME) from filled prescription claims, and risk of motor vehicle crashes, assessed as diagnoses of motor vehicle injuries in claims for emergency visits, inpatient hospitalizations, and ambulance transportation. We estimated associations using a within-individual design, which ruled out all time-stable confounding. We complemented the design with time-varying statistical adjustment for other pharmacotherapies and a negative control pain pharmacotherapy analysis (with incident cyclic antidepressant prescriptions). During 2,150,009 person-years of follow-up, there were 12,123 motor vehicle crashes (5.64 crashes per 1000 person-years). In within-individual comparisons, crash risk was greater during opioid prescription periods involving doses ≤60 MME/day (odds ratio [OR], 3.86; 95% confidence interval [CI], 3.54, 4.21), >60 to 120 MME/day (OR, 5.46; 95% CI, 4.44, 6.73), and >120 MME/day (OR, 3.45; 95% CI, 2.31, 5.15) than during off-treatment periods. The negative control analysis supported the specificity of the results to opioids rather than to other processes associated with pharmacologic pain management. These findings suggest that the receipt of prescription opioids, even at doses ≤60 MME/day, is associated with an increased risk of motor vehicle crashes.

A Comparison of the Effect of Facemasks on Perceived Breathability and Air Quality during Daily Activities and Indoor Exercises

Transmission of COVID-19 occurs predominantly through respired droplets and aerosols containing the SARS-CoV-2 virus. As a solution, face masks have been used to protect against infection. Wearing face masks during indoor exercises is essential to prevent the spread of virus-containing respiratory droplets and aerosols. However, previous studies have not investigated all elements, including the users' perceived breathability (PB) and perceived air quality (PAQ) when wearing a face mask during indoor exercises. The current study aimed to assess users' perceived comfort (PC) of face masks based on assessment criteria of PB and PAQ during moderate to vigorous exercises, and compare them with those during normal daily activities. Data on PC, PB, and PAQ were collected from an online questionnaire survey from 104 participants doing regular moderate to vigorous exercises. Within-subjects comparison with self-controlled case series design was performed to compare PC, PB, and PAQ between wearing face masks during exercises and daily activities. Results showed that the degree of dissatisfaction with PC, PB, and PAQ while wearing face masks and performing indoor exercises is higher than when performing daily activities (p < 0.05). The significance of the study implies that masks comfortable for daily activities may not remain the same during moderate to vigorous exercises, especially during indoor exercises.

Stroke and Myocardial Infarction in Patients with Abdominal Aortic Aneurysm and New-Onset Atrial Fibrillation

OBJECTIVE

 We investigated the association between new-onset atrial fibrillation (AF) and risk of stroke and myocardial infarction (MI) in patients with abdominal aortic aneurysmal (AAA) disease.

METHODS

 Observational crossover study using Danish nationwide data, including patients with AAA and incident AF between 1997 and 2018. We estimated the 1-year risk of stroke and MI and the within-individual odds ratios (ORs) of ischemic events before and after an AF diagnosis, stratified by year of AF diagnosis (1997-2010 and 2011-2018), and supplemented with analyses on changes in use of antithrombotic therapy.

RESULTS

 A total of 3,035 AAA patients were included: 1,040 diagnosed during 1997 to 2010, and 1,995 during 2011 to 2018 (22.2% females, median age 78 years; median CHA₂DS₂-VASc score 4; interquartile range: 3-5). One-year risk of ischemic events after AF was 5.9% (confidence interval [CI] 95%: 4.6-7.5%) and 4.5% (CI 95%: 3.7-5.5%) for stroke and 5.4% (CI 95%: 4.2-6.9%) and 4.0% (CI 95%: 3.2-4.9%) for MI during 1997 to 2010 and 2011 to 2018, respectively. The OR of ischemic stroke before and after incident AF was 2.8 (CI 95%: 1.6-5.2) during 1997 to 2010; and 2.4 (CI 95%: 1.5 to 3.9) during 2011 to 2018, and 3.5 (CI 95%: 1.7-7.5) and 1.5 (CI 95%: 0.9-2.4) for MI. One-year proportion of prescription claims for oral anticoagulants after AF changed from 66.1% in 1997 to 2010 to 82.6% in 2011 to 2018, while antiplatelet prescription claims changed from 80.8 to 60.9%.

CONCLUSION

 Cardiovascular prognosis has improved in patients with prevalent AAA disease and new-onset AF in concordance with optimization of antithrombotic therapy over time. A diagnosis of AF conferred residual risk of stroke and MI.

Methodology of the brodalumab assessment of hazards: a multicentre observational safety (BRAHMS) study

INTRODUCTION

Safe and effective pharmacological treatment is of paramount importance for treating severe psoriasis. Brodalumab, a monoclonal antibody against interleukin (IL) 17 receptor A, was granted marketing authorisation in the EU in 2017. The European Medicines Agency requested a postauthorisation safety study of brodalumab to address potential safety issues raised during drug development regarding major adverse cardiovascular events, suicidal conduct, cancer and serious infections.

METHODS AND ANALYSIS

BRodalumab Assessment of Hazards: A Multinational Safety is a multicentre observational safety study of brodalumab running from 2017 to 2029 using population-based healthcare databases from Denmark, Sweden, Norway, Netherlands, Germany and three different centres in Italy. A distributed database network approach is used, such that only aggregate data are exchanged between sites.Two types of designs are used: a case-time-control design to study acute effects of transient treatment and a variation of the new user active comparator design to study the effects of transient or chronic treatment. As comparators, inhibitors of TNF-α, inhibitors of IL-12 and IL-23, and other inhibitors of cytokine IL-17A are included.In the self-controlled case-time-control design, the risk of developing the outcome of interest during periods of brodalumab use is compared within individuals to the risk in periods without use.In the active comparator cohort design, new users of brodalumab are identified and matched to new users of active comparators. Potential baseline confounders are adjusted for by using propensity score modelling. For outcomes that potentially require large cumulative exposure, an adapted active comparator design has been developed.

ETHICS AND DISSEMINATION

The study is approved by relevant authorities in Denmark, Norway, Sweden, the Netherlands, Germany and Italy in line with the relevant legislation at each site. Data confidentiality is secured by the distributed network approach. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

EUPAS30280.

Changing characteristics over time of individuals receiving COVID-19 vaccines in Denmark: A population-based descriptive study of vaccine uptake

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 received at least one dose of a COVID-19 vaccine from 27 December 2020-29 January 2022. We charted the daily number of newly vaccinated individuals and the cumulative vaccine coverage over time, stratified by vaccine type, age groups and vaccination priority groups, and described characteristics of vaccine recipients during two-month-intervals and in vaccination priority groups.

RESULTS

By 29 January 2022, 88%, 86% and 64% of Danish residents ⩾5 years (n=5,562,008) had received a first, second and third dose, respectively, of a COVID-19 vaccine, most commonly the BNT162b2 vaccine (84%). Uptake ranged from 48% in 5-11-year-olds to 98% in 65-74-year-olds. Individuals vaccinated before June 2021 were older (median age 61-70 years vs 10-35 years in later periods) and had more comorbidities such as hypertension (22-28% vs 0.77-2.8% in later periods), chronic lung disease (9.4-15% vs 3.7-4.6% in later periods) and diabetes (9.3-12% vs 0.91-2.4% in later periods).

CONCLUSIONS

We document substantial changes over time in, for example, age, sex and medical history of COVID-19 vaccine recipients. Though these results are related to the differential vaccine rollout in Denmark, similar findings are probable in other countries and should be considered when designing and interpreting studies on the effectiveness and safety of COVID-19 vaccines.

Evaluation of a Beta-Blocker-Edema-Loop Diuretic Prescribing Cascade: A Prescription Sequence Symmetry Analysis

BACKGROUND

Drug-related adverse events associated with antihypertensive therapy may result in subsequent prescribing of other potentially harmful medications, known as prescribing cascades. The aim of this study was to assess the magnitude and characteristics of a beta-blocker-edema-loop diuretic prescribing cascade.

METHODS

A prescription sequence symmetry analysis was used to assess loop diuretic initiation before and after initiation of beta-blockers among patients 20 years or older without heart failure, atrial fibrillation, other arrythmias, or use of calcium channel blocker within a U.S. private insurance claims database (2005-2018). The temporality of loop diuretic initiation relative to a beta-blocker or negative control (renin-angiotensin system blocker) initiation was tabulated. Secular trend-adjusted sequence ratios (aSRs) with 95% confidence intervals (CIs) compared the initiation of loop diuretic 90 days before and after initiation of beta-blockers.

RESULTS

Among 988,675 beta-blocker initiators, 9,489 patients initiated a new loop diuretic prescription 90 days after and 5,245 patients before beta-blocker initiation, resulting in an aSR of 1.78 (95% CI, 1.72-1.84). An estimated 1.72 beta-blocker initiators per 100 patient-years experienced the prescribing cascade in the first 90 days. The aSR was disproportionately higher among older adults (aSR 1.97), men (aSR 2.25), and patients who initiated metoprolol tartrate (aSR 2.48), labetalol (aSR 2.18), or metoprolol succinate (aSR 2.11). Negative control results (aSR 1.09, 95% CI, 1.05-1.13) generally corroborated our findings, but suggested modest within-person time-varying confounding.

CONCLUSIONS

We observed excess use of loop diuretics following beta-blocker initiation that was only partially explained by secular trends or hypertension progression.

Risk of volume depletion events with concomitant use of sodium glucose co-transporter 2 inhibitors and loop diuretics: A self-controlled case series study

BACKGROUND

Sodium glucose co-transporter 2 inhibitors (SGLT2is) are used to prevent cardiovascular complications in type 2 diabetes mellitus (T2DM) and newly indicated to treat heart failure (HF). Loop diuretics are commonly prescribed to manage volume overload in HF and may increase the risk of volume depletion in real-world practice. This study evaluated the risk of volume depletion following concomitant use of SGLT2is and loop diuretics in veterans.

METHODS

Veterans with T2DM were included if they received concomitant loop diuretics and SGLT2is and experienced at least one volume depletion event between December 2012 and December 2019, utilizing a self-controlled case series design. Concomitant prescribing periods were divided into focal windows of 1 to 14 days, 14 to 28 days, and greater than 28 days. Incidence rate ratios (IRR) were estimated using multivariable Poisson regressions adjusted for age and renal function.

RESULTS

3352 patients experienced at least one volume depletion event and were concomitantly prescribed SGLT2is and loop diuretics at least once. The risk of volume depletion increased in the treatment versus control windows during the 1 to 14-day window (IRR = 1.82, 95% CI 1.63-2.02) the 15-to-28-day window (IRR = 1.46, 95% CI 1.28-1.67), and the greater than 28-day window (IRR = 1.22, 95% CI 1.21-1.34).

CONCLUSIONS

Concomitant prescribing of SGLT2is and loop diuretics is associated with an increased risk of volume depletion, an effect that attenuates with longer therapy durations. Prescribers need to closely monitor fluid status in patients receiving concomitant therapy, especially those with advancing age or with eGFR below 60.

Adverse Events Associated With Coprescription of Phosphodiesterase Type 5 Inhibitors and Oral Organic Nitrates in Male Patients With Ischemic Heart Disease : A Case-Crossover Study

BACKGROUND

Concomitant use of oral organic nitrates (nitrates) and phosphodiesterase type 5 (PDE5) inhibitors is contraindicated.

OBJECTIVE

To measure temporal trends in the coprescription of nitrates and PDE5 inhibitors and to measure the association between cardiovascular outcomes and the coprescription of nitrates with PDE5 inhibitors.

DESIGN

Case-crossover design.

SETTING

Nationwide study of Danish patients from 2000 to 2018.

PATIENTS

Male patients with International Classification of Diseases, 10th Revision (ICD-10) codes for ischemic heart disease (IHD), including those who had a continuing prescription for nitrates and a new, filled prescription for PDE5 inhibitors.

MEASUREMENTS

Two composite outcomes were measured: 1) cardiac arrest, shock, myocardial infarction, ischemic stroke, or acute coronary arteriography and 2) syncope, angina pectoris, or drug-related adverse event.

RESULTS

From 2000 to 2018, 249 541 male patients with IHD were identified. Of these, 42 073 patients had continuing prescriptions for nitrates. During this period, the prescription rate for PDE5 inhibitors in patients with IHD who were taking nitrates increased from an average of 0.9 prescriptions (95% CI, 0.5 to 1.2 prescriptions) per 100 persons per year in 2000 to 19.5 prescriptions (CI, 18.0 to 21.1 prescriptions) in 2018. No statistically significant association was found between the coprescription of nitrates with PDE5 inhibitors and the risk for either composite outcome (odds ratio [OR], 0.58 [CI, 0.28 to 1.13] for the first outcome and OR, 0.73 [CI, 0.40 to 1.32] for the second outcome).

LIMITATION

An assumption was made that concurrently filled prescriptions for nitrates and PDE5 inhibitors equaled concomitant use.

CONCLUSION

From 2000 to 2018, the use of PDE5 inhibitors increased 20-fold among Danish patients with IHD who were taking nitrates. A statistically significant association between concomitant use of these medications and cardiovascular adverse events could not be identified.

PRIMARY FUNDING SOURCE

Ib Mogens Kristiansens Almene Fond and Helsefonden.

Preconception Antidiabetic Drugs in Men and Birth Defects in Offspring : A Nationwide Cohort Study

BACKGROUND

Diabetes reduces semen quality and increasingly occurs during reproductive years. Diabetes medications, such as metformin, have glucose-independent effects on the male reproductive system. Associations with birth defects in offspring are unknown.

OBJECTIVE

To evaluate whether the risk for birth defects in offspring varies with preconceptional pharmacologic treatment of fathers with diabetes.

DESIGN

Nationwide prospective registry-based cohort study.

SETTING

Denmark from 1997 to 2016.

PARTICIPANTS

All liveborn singletons from mothers without histories of diabetes or essential hypertension.

MEASUREMENTS

Offspring were considered exposed if their father filled 1 or more prescriptions for a diabetes drug during the development of fertilizing sperm. Sex and frequencies of major birth defects were compared across drugs, times of exposure, and siblings.

RESULTS

Of 1 116 779 offspring included, 3.3% had 1 or more major birth defects (reference). Insulin-exposed offspring (n = 5298) had the reference birth defect frequency (adjusted odds ratio [aOR], 0.98 [95% CI, 0.85 to 1.14]). Metformin-exposed offspring (n = 1451) had an elevated birth defect frequency (aOR, 1.40 [CI, 1.08 to 1.82]). For sulfonylurea-exposed offspring (n = 647), the aOR was 1.34 (CI, 0.94 to 1.92). Offspring whose fathers filled a metformin prescription in the year before (n = 1751) or after (n = 2484) sperm development had reference birth defect frequencies (aORs, 0.88 [CI, 0.59 to 1.31] and 0.92 [CI, 0.68 to 1.26], respectively), as did unexposed siblings of exposed offspring (3.2%; exposed vs. unexposed OR, 1.54 [CI, 0.94 to 2.53]). Among metformin-exposed offspring, genital birth defects, all in boys, were more common (aOR, 3.39 [CI, 1.82 to 6.30]), while the proportion of male offspring was lower (49.4% vs. 51.4%, P = 0.073).

LIMITATION

Information on underlying disease status was limited.

CONCLUSION

Preconception paternal metformin treatment is associated with major birth defects, particularly genital birth defects in boys. Further research should replicate these findings and clarify the causation.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Bleeding Risk Following Systemic Fluconazole or Topical Azoles in Patients with Atrial Fibrillation on Apixaban, Rivaroxaban, or Dabigatran

BACKGROUND

Bleeding safety in relation to use of systemic fluconazole and topical azoles among patients with atrial fibrillation treated with apixaban, rivaroxaban, or dabigatran is insufficiently explored, despite clinical relevance and several reports suggesting associations.

METHODS

Using nationwide Danish registers, we identified patients with atrial fibrillation initiated on apixaban, rivaroxaban, or dabigatran from 2012-2018. We investigated associations between bleeding incidents and systemic fluconazole or topical azole treatment using a case-crossover design with 30-day exposure windows and reported odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

We included 32,340 (36%), 32,409 (36%), and 24,940 (28%) patients initiated on apixaban, rivaroxaban, and dabigatran, respectively. Patients on apixaban were older (median age: 77 years; interquartile range [IQR] 70-84) compared with rivaroxaban users (median age: 75 years; IQR 68-82) and patients on dabigatran (median age: 73 years; IQR 66-80). Apixaban users had a significantly increased risk of bleeding following exposure to systemic fluconazole: odds ratio (OR) 3.5; 95% confidence interval (CI), 1.4-10.6. No increased risk was found among rivaroxaban and dabigatran users: ORs of 0.9 (95% CI, 0.2-3.0) and 1.7 (95% CI, 0.5-5.6), respectively. As to bleeding risk pertaining to topical azole exposure among apixaban, rivaroxaban, and dabigatran users, no association was found, with corresponding ORs of 0.8 (95% CI, 0.5-1.3); 1.3 (95% CI, 0.9-2.1); and 1.2 (95% CI 0.8-1.8), respectively.

CONCLUSION

In patients with atrial fibrillation on either apixaban, rivaroxaban, or dabigatran, an association between an elevated bleeding risk and use of systemic fluconazole was found among patients on apixaban. We found no increased risk of bleeding following co-exposure to topical azoles.

Sampling in the case-time-control design among drug users when outcome prevents further treatment

PURPOSE

The objective of this paper is to advocate a new way of sampling controls in the case-time-control design in a cohort of drug users when the studied outcome prevents further treatment.

METHODS

Mathematically we demonstrate how a standard sampling of controls, where controls are sampled among all subjects without an event at end-of-study, leads to a biased effect estimate. We propose to add the requirement that controls initiate treatment before the calendar time of event of their matched case to circumvent this. The standard and proposed sampling methods are compared in a simulation study and in an empirical data example examining the effect of nonsteroidal anti-inflammatory drug usage on the risk of upper gastrointestinal bleeding.

RESULTS

When the controls are sampled the standard way, the case-time-control design confers a bias because cases and controls have a different time-trend of exposure. The bias has been upwards in all the scenarios we have investigated. The requirement we add to be a potential control ensures that cases and controls have the same time-trend of exposure when treatment and outcome are independent. The simulation study confirms that the proposed sampling method removes the bias between treatment and outcome. The proposed sampling method lowered the odds-ratio estimate from 3.72 to 3.26 in the data example.

CONCLUSION

The proposed sampling method makes it possible to use the case-time-control design in a cohort of subjects with registered use of a drug when outcome prevents further treatment.

Evaluation of the key prescription sequence symmetry analysis assumption using the calcium channel blocker: Loop diuretic prescribing cascade

OBJECTIVES

To evaluate the prescription sequence symmetry analysis assumption regarding balance between marker drug (i.e., medication used to treat a drug-induced adverse event) initiation rates before and after initiation of an index drug (i.e., medication that is potentially associated with the drug-induced adverse event) in the absence of prescribing cascades, we used a well-described example of loop diuretic initiation to treat dihydropyridine calcium channel blockers (DH CCB)-induced edema.

STUDY DESIGN AND SETTING

The University of Florida Health Integrated Data Repository from June 2011 and July 2018 was used to assess temporal prescribing of DH CCB and loop diuretics within the prescription sequence symmetry analysis framework. Validation of the prescribing cascade was performed via clinical expert chart review.

RESULTS

Among patients without heart failure who were initiated on DH CCB, 26 and 64 loop diuretics initiators started within 360 days before versus after DH CCB initiation, respectively, resulting in an adjusted sequence ratio (aSR) of 2.27 (95% CI, 1.44-3.58). Overall, 35 (54.7%) patients were determined to have a prescribing cascade. Removing patients who experienced a prescribing cascade resulted in an aSR of 1.05, 95% CI 0.62-1.78).

CONCLUSION

Loop diuretic initiation rates before and after DH CCB initiation for reasons other a prescribing cascade were similar, thus confirming the prescription sequence symmetry analysis assumption.

Respiratory tract infection and risk of bleeding in oral anticoagulant users: self-controlled case series

OBJECTIVE

To estimate the association between untreated, community acquired, respiratory tract infections and bleeding in oral anticoagulant users.

DESIGN

Self-controlled case series.

SETTING

General practices in England contributing data to the Clinical Practice Research Datalink GOLD.

PARTICIPANTS

1208 adult users of warfarin or direct oral anticoagulants with a general practice or hospital admission record of a bleeding event between January 2010 and December 2019, and a general practice record of a consultation for a community acquired respiratory tract infection for which immediate antibiotics were not prescribed (that is, untreated).

MAIN OUTCOME MEASURES

Relative incidence of major bleeding and clinically relevant non-major bleeding in the 0-14 days after an untreated respiratory tract infection, compared to unexposed time periods.

RESULTS

Of 1208 study participants, 58% (n=701) were male, median age at time of first bleed was 79 years (interquartile range 72-85), with a median observation period of 2.4 years (interquartile range 1.3-3.8). 292 major bleeds occurred during unexposed time periods and 41 in the 0-14 days after consultation for a respiratory tract infection. 1003 clinically relevant non-major bleeds occurred during unexposed time periods and 81 in the 0-14 days after consultation for a respiratory tract infection. After adjustment for age, season, and calendar year, the relative incidence of major bleeding (incidence rate ratio 2.68, 95% confidence interval 1.83 to 3.93) and clinically relevant non-major bleeding (2.32, 1.82 to 2.94) increased in the 0-14 days after an untreated respiratory tract infection. Findings were robust to several sensitivity analyses and did not differ by sex or type of oral anticoagulant.

CONCLUSIONS

This study observed a greater than twofold increase in the risk of bleeding during the 0-14 days after an untreated respiratory tract infection. These findings have potential implications for how patients and clinicians manage oral anticoagulant use during an acute intercurrent illness and warrant further investigation into the potential risks and how they might be mitigated.

Does Transient Opioid Use Increase Risk of Short-Term Respiratory Exacerbation among Older Adults with Chronic Obstructive Pulmonary Disease?

The objective of this study was to examine the association between transient opioid use and acute respiratory exacerbations among older Medicare beneficiaries with COPD. This study was conducted using national Medicare 5% sample administrative claims data between 2012 and 2016 and employed a case-crossover design. The date of eligible COPD exacerbation events was defined as the index date and the presence of opioid prescriptions during a 7-day exposure window prior to index date was compared to a set of 10 control periods, each 7-days long. The association between opioid exposure and COPD exacerbation was estimated using a conditional logistic regression with robust sandwich estimators, after accounting for known time-varying confounders. Among 16,290 eligible COPD exacerbations included in the study sample, the average patient age was 77.08 years, and 64.2% of events occurred in women. Transient exposure to opioids was associated with a 76% increase in the odds of an acute COPD exacerbation (OR: 1.76, 95%CI: 1.67-1.84), and each 25 mg increase in morphine milligram equivalent dose was associated with a 18% increase in the odds of exacerbation (OR: 1.18, 95% CI: 1.15-1.21). Effect estimates were consistent across subgroup analyses conducted among events identified in the emergency department versus hospital, and among individuals with a single exacerbation event versus those with multiple exacerbations. Transient exposure to opioids was associated with an increased short-term risk of respiratory exacerbation among older adults with COPD. Treatment decisions for breathlessness among individuals with COPD need to account for the benefit-risk profile of opioids.Supplemental data for this article is available online at https://doi.org/10.1080/15412555.2021.2013460 .

Evaluating the use of prescription sequence symmetry analysis as a pharmacovigilance tool: A scoping review

BACKGROUND

The (prescription) sequence symmetry analysis (PSSA) design has been used to identify potential prescribing cascade signals by assessing the prescribing sequence of an index drug relative to a marker drug presumed to treat an adverse drug event provoked by the index drug.

OBJECTIVES

This review aimed to explore the use of the PSSA design as a pharmacovigilance tool with a particular focus on the breadth of identified signals and advances in PSSA methodology.

METHODS

We searched Embase, PubMed/Medline, Google Scholar, Web of Science and grey literature to identify studies that used the PSSA methodology. Two reviewers independently extracted relevant data for each included article. Study characteristics including signals identified, exposure time window, stratified analyses, and use of controls were extracted.

RESULTS

We identified 53 studies which reported original results obtained using PSSA methodology or quantified the validity of components of the PSSA design. Of those, nine studies provided validation metrics showing reasonable sensitivity and high specificity of PSSA to identify prescribing cascade signals. We identified 340 unique index drug - marker drug signals published in the PSSA literature, representing 281 unique index - marker pharmacological class dyads (i.e., unique fourth-level Anatomical Therapeutic Chemical [ATC] classification dyads). Commonly observed signals were identified for index drugs acting upon the nervous system (34%), cardiovascular system (21%), and blood and blood-forming organs (15%), and many marker drugs were related to the nervous system (25%), alimentary tract and metabolism (23%), cardiovascular system (17%), and genitourinary system and sex hormones (14%). Negative controls and positive controls were utilized in 21% and 13% of studies, respectively.

CONCLUSIONS

The PSSA methodology has been used in 53 studies worldwide to detect and evaluate over 300 unique prescribing cascades signals. Researchers should consider sensitivity analyses incorporating negative and/or positive controls and additional time windows to evaluate time-varying biases when designing PSSA studies.

Association between methylphenidate and risk of myocardial infarction: A multinational self-controlled case series study

PURPOSE

To investigate the association between use of methylphenidate and risk of myocardial infarction among Asians.

METHODS

We conducted a multinational self-controlled case series study using nationwide healthcare databases of South Korea (2002-2018), Taiwan (2004-2015), and Hong Kong (2001-2016). Of patients with myocardial infarction who were also prescribed methylphenidate within the observation period, methylphenidate use was classified into four mutually exclusive periods by each person-day: exposed (exposed to methylphenidate), pre-exposure (prior to the first methylphenidate prescription), washout (after the end of methylphenidate treatment), and baseline (unexposed to methylphenidate). Risk of myocardial infarction among the three periods of methylphenidate use was compared to the baseline period using conditional Poisson regression analysis to estimate incidence rate ratios (IRRs) with 95% confidence intervals (CIs).

RESULTS

We identified 2104, 484, and 30 patients from South Korea, Taiwan, and Hong Kong, respectively. Risk of myocardial infarction was the highest during the pre-exposure period in all three populations: South Korea, pre-exposure (IRR 3.17, 95% CI 3.04-3.32), exposed (1.05, 1.00-1.11), washout (1.92, 1.80-2.04); Taiwan, pre-exposure (1.97, 1.78-2.17), exposed (0.72, 0.65-0.80), washout (0.56, 0.46-0.68); Hong Kong, pre-exposure (18.09, 8.19-39.96), exposed (9.32, 3.44-25.28), washout (7.69, 1.72-34.41). Following stratification for age and sex, the trends remained analogous to the main findings across all three populations.

CONCLUSIONS

Although a positive association between initiating methylphenidate and the onset of myocardial infarction was observed, the risk was the highest in the period before its initiation. Thus, this multinational study suggests there was no causal relationship between methylphenidate and myocardial infarction among Asians.

Control yourself: ISPE-endorsed guidance in the application of self-controlled study designs in pharmacoepidemiology

PURPOSE

Consensus is needed on conceptual foundations, terminology and relationships among the various self-controlled "trigger" study designs that control for time-invariant confounding factors and target the association between transient exposures (potential triggers) and abrupt outcomes. The International Society for Pharmacoepidemiology (ISPE) funded a working group of ISPE members to develop guidance material for the application and reporting of self-controlled study designs, similar to Standards of Reporting Observational Epidemiology (STROBE). This first paper focuses on navigation between the types of self-controlled designs to permit a foundational understanding with guiding principles.

METHODS

We leveraged a systematic review of applications of these designs, that we term Self-controlled Crossover Observational PharmacoEpidemiologic (SCOPE) studies. Starting from first principles and using case examples, we reviewed outcome-anchored (case-crossover [CCO], case-time control [CTC], case-case-time control [CCTC]) and exposure-anchored (self-controlled case-series [SCCS]) study designs.

RESULTS

Key methodological features related to exposure, outcome and time-related concerns were clarified, and a common language and worksheet to facilitate the design of SCOPE studies is introduced.

CONCLUSIONS

Consensus on conceptual foundations, terminology and relationships among SCOPE designs will facilitate understanding and critical appraisal of published studies, as well as help in the design, analysis and review of new SCOPE studies. This manuscript is endorsed by ISPE.