Background: Few studies assessing the use of epinephrine in drug-induced anaphylaxis (DIA) in the hospital setting are available. We utilized the Beijing Pharmacovigilance Database (BPD) to evaluate the appropriateness of epinephrine for DIA management. Methods: DIA cases collected in the BPD from January 2004 to December 2014 were adjudicated and analyzed for demographics, causative drugs, clinical signs, outcomes, initial treatment, route, dosing, and cardiovascular adverse events (CAE) of epinephrine. Results: DIA was primarily caused by antibiotics (38.4%), radiocontrast agents (11.9%), traditional Chinese medicine injections (10.9%), and chemotherapeutic drugs (10.3%). Only 708 (59.5%) patients received epinephrine treatment. Patients who received epinephrine were more likely to experience wheezing (p < 0.001) and respiratory arrest (p < 0.001). Among 518 patients with a complete record of the epinephrine administration route, the percentage of patients receiving it by intramuscular (IM) injection, subcutaneous (SC) injection, intravenous (IV) bolus injection, or IV continuous infusion was 16.9, 31.5, 43.5, and 8.1%, respectively. Among the 427 patients with a record of both the administration route and the dosing, an overdose was more likely with IV bolus (94.1%) in contrast to IM injection (56.6%; p < 0.001) or SC injection (43.7%; p < 0.001). Among the patients analyzed for CAE (n = 349), 17 patients accounted for 19 CAE, and 13 (76.5%) of these patients were overdosed with epinephrine. Conclusion: Underuse, inappropriate IV bolus use, and overdosing were the 3 major problems with epinephrine use in DIA in China. Educational training for health care professionals on the appropriate use of epinephrine in managing anaphylactic reactions is suggested.

Anaphylaxis is a severe life-threatening systemic allergic reaction with a sudden onset that usually develops after exposure to an offending agent. Common triggers of anaphylaxis include food, hymenoptera venom, and drugs [1,2]. Anaphylaxis is a medical emergency requiring rapid recognition and prompt management. Epinephrine is the recommended first-line treatment [3], and its delayed administration is an important risk factor for fatal anaphylaxis [2,3].

Drugs are one of the most common causes of anaphylaxis [2]. According to a study by Jerschow et al. [4], drugs were the most common cause of 2,458 anaphylaxis-related deaths (58.8%) in the USA from 1999 to 2010. Recent evidence suggests that the prevalence of drug-induced anaphylaxis (DIA) in inpatients is approximately 0.03%, with a mortality rate of 3-9% [5]. However, most previous studies assessing anaphylaxis management have been limited to patients presenting to emergency departments (ED) [6,7,8,9,10,11] or outpatient allergy clinics [12,13,14]. Very few studies have been conducted to assess the use of epinephrine in patients who developed DIA in generalized clinical settings. Considering the prevalence and the potential severity of DIA, it is important for healthcare providers to manage DIA patients appropriately in the various clinical settings including outpatient, inpatient, and ED.

Thus, the objective of our study was to assess the use of epinephrine in patients who developed DIA in clinical settings using the Beijing Pharmacovigilance Database (BPD). Cases from the BPD were reported by health care professionals for patients who had DIA during patient encounters. The outcomes of interests were: (1) to analyze whether epinephrine was used and whether it was used as an initial treatment (first medication administered) to manage anaphylaxis, (2) to assess the route of administration (intramuscular [IM], subcutaneous [SC], intravenous [IV] bolus, or IV continuous infusion) and the dose utilized, and (3) to analyze whether any relationship exists between the dose used and the incidence of cardiovascular adverse events (CAE) associated with epinephrine.

Data Sources

The BPD used in this study was provided by the Beijing Adverse Drug Reaction Monitoring Center. The BPD contains records of severe adverse drug event (ADE) cases reported from 94 hospitals in the Beijing region. Its intent is to obtain well-defined, standardized data of affected patients experiencing ADE in the Beijing region of China. In each clinical setting (inpatient, outpatient, and ED), ADE are typically reported by physicians, pharmacists, and nurses to the respective pharmacy department. The widely accepted World Health Organization-Uppsala Monitoring Center (WHO-UMC) criteria were used to assess causality, and Certain and Probable/Likely categories were applied for the identification of an offending agent [15]. Once a case is confirmed as a severe ADE [16] (defined as at least one of the following outcomes: death, life-threatening symptoms, initial or prolonged hospitalization, disability or permanent damage, congenital anomaly or birth defect, requirement of intervention to prevent permanent impairment or damages, and other serious medical events), the patient's data are electronically reported to the BPD by a pharmacist. BPD reports include the following information: the severity of the ADE, demographic variables (gender, age, current disease, history of ADE, and history of family member ADE), triggering prescriptions (brand and generic name, formulation, dose, unit, frequency, route, initial and end dates, and indication), and a description of the ADE. The ADE information includes the reporting time, the category (anaphylaxis, pneumonia, gastrointestinal bleeding, myocardial infarction, etc.), the severity (moderate or severe), the onset date, a detailed description (symptoms, lab data, treatment, etc.), and the outcome (death, recovery, or improvement).

This study was exempt from further review by the Institutional Review Board of Peking University Third Hospital. Informed consent was not required from patients because this was a retrospective study using only deidentified data.

Database Inquiry

We downloaded the BPD database for the period covering January 1, 2004, to December 31, 2014, and assembled a base cohort that included all patients with a reported drug-induced acute allergic reaction or anaphylaxis using the following search terms: “anaphylaxis,” “anaphylactic shock,” “allergy,” “allergic reaction,” and “hypersensitivity.” Prior to excluding mild hypersensitivity reactions from the base cohort, mutually exclusive definitions for drug-related allergic reactions and anaphylaxis using standard definitions [3,6] were created by 2 physicians, i.e., an emergency physician (B.W.) and a pediatric allergist (Y.X.) (detailed information on the definition and severity of anaphylaxis is shown in online suppl. Appendix 1; see www.karger.com/doi/10.1159/000475498 for all online suppl. material). Patients with acute allergic reactions (grade 1) had only cutaneous involvement, whereas patients with anaphylaxis were those presenting with grade 2 or 3 reactions; patients with grade 2 reactions had mild-to-moderate manifestations of anaphylaxis, and those with grade 3 reactions had severe presentations with cutaneous, gastrointestinal, and potentially life-threatening respiratory or cardiovascular signs and symptoms [6].

Then the search terms “anaphylaxis,” “anaphylactic reaction,” “shock,” “convulsion,” “cardiac arrest,” “respiratory arrest,” “cyanosis,” and “death” were used toidentify patients with a potential anaphylaxis (grade 2 and 3 reactions). Eligibility required a complete record that included the patient's age, gender, trigger medications, anaphylactic symptoms, and treatment. Approximately 14.9% of the patients were excluded due to incomplete records.

Data Extraction

For patients with a potential anaphylaxis identified by the search terms in the BPD, we developed a data extraction form to validate the diagnosis and severity of anaphylaxis and the use of epinephrine. The following free-text information was collected: (1) demographic variables and trigger prescriptions, (2) anaphylactic symptoms from different organ systems according to previous guidelines and literature [3,10,17,18], (3) drugs that were used to treat the anaphylaxis (nonepinephrine anaphylaxis treatment included corticosteroids, antihistamines, and bronchodilators), and (4) the use of epinephrine (whether it was used as an initial treatment, the administration route, the dosing, and adverse events). We pretested the extraction form on database records from 250 patients and revised the form based on this pretest. Then, 2 trained extractors independently performed the extraction to ensure consistency; discrepancies were resolved by an investigator with experience in standardized medical record extraction (T.W.).

Adjudication

The physician adjudicators (B.W. and Y.X.) independently reviewed the information extracted from each case, determining the diagnosis of anaphylaxis and the case severity, as well as any CAE associated with the use of epinephrine. Physician reviewers used the published clinical diagnosis of anaphylaxis [1] and the severity definition [6] as a gold standard and referred to a recent publication by Campbell et al. [19] to judge the occurrence of epinephrine adverse events. Disagreement was dealt with through discussion. Patients with an acute allergic reaction were excluded and only those who met the diagnostic criteria for anaphylaxis were included in the analysis.

Study Design

The frequency of the initial administration route of epinephrine was assessed according to the severity of anaphylaxis reported. To analyze overdosage of epinephrine, epinephrine overdose for adults was defined as a dose that exceeded the recommended dose, i.e., 0.01 mg/kg body weight, with a maximum dose of 0.5 mg for IM and SC injections or 0.1 mg given by IV bolus [19,20,21,22,23]. Accordingly, the initial epinephrine dosing for adults was analyzed by different administration routes (IM, SC, and IV) and categorized as nonoverdose or overdose (≤0.5 vs. >0.5 mg for both IM and SC, and ≤0.1 vs. >0.1 mg for IV bolus). The initial pediatric epinephrine dosing was categorized as nonoverdose or overdose [21,24,25] based on weight-based dosing (≤0.01 vs. >0.01 mg/kg for IM and SC, with a maximum dose of 0.5 mg, or 0.001 mg/kg for the IV bolus route, with a maximum dose of 0.1 mg). When body weights were not available, pediatric IM/SC epinephrine dosing was assessed according to the child's age group (<6, 6-12, or >12 years) as suggested in the literature [21]. For IV bolus injections, age was used to estimate the body weight [26] to calculate the dose. In both adults and children, overdosing with IV continuous infusion was not analyzed since continuous infusion is usually titrated to clinical effects and not all of the information necessary to calculate the total dose was available.

The inclusion criteria for evaluation of CAE of epinephrine were: (1) records reporting both the administration route and the dosing of epinephrine (35.2% patients with missing values were excluded), (2) signs and symptoms of cardiovascular complications that developed after epinephrine administration where the onset was temporally related (within several minutes or noted on the next set of vital signs) to epinephrine administration, and (3) no concurrent use of epinephrine-like medications (e.g., norepinephrine and dopamine) or reporting of CAE prior to the use of such epinephrine-like drugs. CAE were defined according to Campbell et al. [19]. Hypertension was considered an adverse event if there was a recorded systolic blood pressure ≥180 mm Hg or a diastolic blood pressure ≥120 mm Hg. Cardiac ischemia required both a documented troponin T level elevation and symptoms suggestive of cardiac ischemia, such as chest tightness, pressure, or pain (detailed information is shown in online suppl. Appendix 2).

Variables that influenced the choice of therapy (epinephrine or nonepinephrine) for DIA patients were identified. The key baseline information, organ system involvements, and other nonepinephrine acute therapies to treat anaphylaxis in epinephrine and nonepinephrine users were compared.

Statistical Analysis

The statistical analysis was performed using SPSS version 22 (SPSS Inc., USA). Continuous variables were subjected to normality tests using a single-sample Kolmogorov-Smirnov test, and data with a normal distribution were expressed as means ± SD, those with a nonnormal distribution were expressed as medians (range), and the dichotomous variables were described as frequencies (%). Continuous variables were compared using an independent samples t test, while dichotomous variables were compared using the Pearson χ2 test or Fisher's exact test. To identify independent clinical features (risk factors) associated with patients receiving epinephrine, bivariate logistic regression was used to derive OR and 95% CI of different variables. Variables with p values <0.2 in the bivariate analysis were included in a multivariate logistic regression analysis using forward stepwise selection processes. All tests were 2-tailed, and p < 0.05 was considered statistically significant.

Demographic and Clinical Characteristics

Using our search terms, 9,425 patients with drug-induced hypersensitivity reactions were identified from the BPD. Of those, 1,189 patients with adjudicated anaphylaxis were included in our analysis (Fig. 1). Among these patients, the mean age was 47.6 years, 627 (52.7%) were female, and 91 (7.7%) were children (age <18 years) (Table 1). Among the 1,172 DIA cases with a clearly reported occurrence setting (inpatient, outpatient, or ED), the majority of the patients (1,128; 96.2%) developed anaphylaxis during their hospital stays. Forty-three patients presented to an ED, and only 1 patient developed anaphylaxis in the outpatient setting and did not receive any treatment (Table 1). Among the 1,128 inpatients, the number of patients who received anaphylaxis treatment in an ED and in a non-ED setting was 123 and 1,005, respectively. The top 4 triggers of DIA were antibiotics (38.4%), radiocontrast agents (11.9%), traditional Chinese medicine injections (10.9%), and chemotherapeutic drugs (10.3%). The majority of patients (83.8%) experienced cardiovascular anaphylactic symptoms (82.8, 4.5, and 5.5% for hypotension, cardiac arrest, and incontinence, respectively). The percentage of patients who developed mucocutaneous compromise, respiratory compromise, and central nervous system symptoms was 47.4, 55.4, and 50.1%, respectively. Only 31.3% of the patients had gastrointestinal anaphylactic symptoms. Overall, 73 (6.1%) patients were admitted to an intensive care unit and 39 (3.3%) patients died of anaphylaxis during hospitalization.

Table 1

Demographic and clinical characteristics of patients with drug-induced anaphylaxis

Demographic and clinical characteristics of patients with drug-induced anaphylaxis
Demographic and clinical characteristics of patients with drug-induced anaphylaxis
Fig. 1

Number of patients in the base cohort and the study cohort. ADE, adverse drug event.

Fig. 1

Number of patients in the base cohort and the study cohort. ADE, adverse drug event.

Close modal

Analysis of Therapies for the Treatment of Anaphylaxis

Of the 708 patients (59.5%) who received epinephrine treatment (Table 2), 699 had adequate documentation for analysis. Among them, 518 patients (74.1%) were administered epinephrine as an initial treatment, and 409 of 518 patients were coadministered corticosteroids. Of the 518 patients, 26 were excluded since they presented cardiac or respiratory arrest prior to the administration of epinephrine. The number of patients who received IM, SC, IV bolus injection, and IV continuous infusion was 83 (16.9%), 155 (31.5%), 214 (43.5%), and 40 (8.1%), respectively (Table 3). The median dosing for the IM, SC, and IV bolus injection routes was 1.0 (0.10-5.00), 0.5 (0.10-3.00), and 1.0 mg (0.04-5.00), respectively. Of the 1,189 anaphylactic patients, 977 (82.2%) received corticosteroids, and for 904 (92.5%) of them it was the initial therapy; 344 (28.9%) received antihistamines, and only 40 (3.4%) received bronchodilators.

Table 2

Clinical features associated with epinephrine therapy

Clinical features associated with epinephrine therapy
Clinical features associated with epinephrine therapy
Table 3

Route of epinephrine administration according to the severity of anaphylaxis

Route of epinephrine administration according to the severity of anaphylaxis
Route of epinephrine administration according to the severity of anaphylaxis

Patients who received epinephrine during the course of anaphylactic treatment did not differ significantly from those who did not receive it with regard to gender or current disease (Table 2). In contrast, there was a significant difference between those who received epinephrine and those who did not in terms of age (mean 46.6 vs. 49.1 years, p = 0.032), risk of mortality (34 vs. 5 patients, OR 4.81; 95% CI 1.87-12.39), and intensive care unit admission (53 vs. 20 patients, OR 1.86; 95% CI 1.10-3.16). The severity of anaphylaxis was significantly different between the epinephrine group and the nonepinephrine group. There was a higher proportion of respiratory arrest (OR 3.09; 95% CI 1.77-5.39) and cardiac arrest (OR 3.48; 95% CI 1.68-7.19) in the epinephrine group compared to the nonepinephrine group. In cases of death in the epinephrine group, 19 of 34 (55.9%) patients experienced the onset of respiratory or cardiac arrest prior to the administration of epinephrine. Fifteen of 34 (44.1%) patients did not receive epinephrine as the initial treatment (online suppl. Appendix 3). Among 9 patients who received epinephrine as the initial treatment prior to respiratory or cardiac arrest, 2 were treated in community hospitals and underwent a referral process, and 3 experienced contrast media-induced anaphylaxis, resulting in severe anaphylaxis within 10 min. In the multivariate analysis, clinical features associated with receiving epinephrine were age (OR per 10-year increase in age: 0.91; 95% CI 0.86-0.97), flushing (OR 0.70; 95% CI 0.52-0.96), diffuse urticaria (OR 1.43; 95% CI 1.06-1.91), wheezing (OR 1.96; 95% CI 1.47-2.62), and respiratory arrest (OR 3.67; 95% CI 2.07-6.49). Patients who received epinephrine were also more likely to receive corticosteroids (OR 2.02; 95% CI 1.48-2.76) and less likely to receive bronchodilators (OR 0.44; 95% CI 0.23-0.84).

Analysis of the Initial Administration Route and the Initial Dosing of Epinephrine

There was a significant difference in the use of different administration routes (p < 0.001), but there was no significant difference in terms of anaphylaxis severity between the administration routes (p = 0.402; Table 3). There was a significant difference between overdose rates per administration route (p < 0.001; Table 4). An overdose was more likely with the IV bolus route (94.1%) compared to IM (56.6%, p < 0.001) and SC routes (43.7%, p < 0.001). There was no association with anaphylaxis severity for any administration route (p = 0.441; Table 4). Among a total of 178 patients who experienced perioperative DIA, 78 patients received epinephrine administration with a clearly documented administration route, including 2 (2.6%) via the IM route, 7 (9.0%) via the SC route, 20 (25.6%) via IV continuous infusion, and 49 (62.8%) via IV bolus.

Table 4

Route of epinephrine administration and overdose according to the severity of anaphylaxis

Route of epinephrine administration and overdose according to the severity of anaphylaxis
Route of epinephrine administration and overdose according to the severity of anaphylaxis

Analysis of CAE of Epinephrine

Among a total of 349 patients eligible for analysis of CV complications associated with epinephrine (Table 5), 17 patients developed 19 CAE, and 13 (76.5%) of them were overdosed. Patients who received IM epinephrine had no adverse events, 2 (11.8%) patients who received SC epinephrine had arrhythmia events, and 15 (88.2%) patients, including 1 child, who received an IV bolus injection had 17 CV events. Patients who received an epinephrine IV bolus (9.62%) were more likely to have adverse CV events than patients who received epinephrine via IM (0.00%, p = 0.016) or SC (1.64%, p = 0.006) injections.

Table 5

Cardiovascular adverse events associated with routes of epinephrine administration

Cardiovascular adverse events associated with routes of epinephrine administration
Cardiovascular adverse events associated with routes of epinephrine administration

As far as we know, our study is the first to assess epinephrine use in patients with DIA using a large pharmacovigilance database from China. Use of the BPD permitted the collection of data on patients who received epinephrine for DIA in both ED and non-ED settings. Therefore, we are able to present the largest community-based cohort of patients with DIA. To our knowledge, this is the first study to evaluate epinephrine use in patients with DIA in a variety of clinical settings. The number of patients treated in an ED was lower than the number of inpatients and, because the BPD database includes patients with drug adverse events only, other triggers (food, venom, etc.) of anaphylaxis from ED were not included in our study. Consistent with previous studies [4,5,27,28], the most common triggers of DIA in our patient population were antibiotics, radiocontrast agents, and chemotherapeutic drugs. Notably, our data suggests that, in addition to these known triggers, traditional Chinese medicine injections are one of the top triggers of DIA in Beijing, which is consistent with a recent study by Jiang et al. [11]. Further studies regarding the safety of traditional Chinese medicine injections are thus warranted [29]. A high proportion of patients developed cardiovascular symptoms (83.8%), and the mortality rate of 3.3% was comparable to those of previous studies [5,30]. Most cases of DIA developed during patient hospitalizations and were managed by non-ED health care providers. The analysis suggests that epinephrine use in patients with DIA could be improved in the region studied.

Utilization of Epinephrine in Anaphylaxis Management

Epinephrine should be administered to anaphylaxis patients as a first-line treatment because a delayed administration has been shown to result in poor outcomes and fatality [10,20]. Corticosteroids are not effective in acute anaphylaxis management [2,3,20,31], and neither are antihistamines [31,32,33]. Overall, epinephrine is underused for DIA in the Beijing region, which is in line with previous studies [11,34]. Our data indicates a low rate (59.5%) of epinephrine use and a suboptimal timing of use, with only 74.1% of patients receiving it as the initial treatment. Clinicians are more inclined to administer epinephrine to patients with respiratory symptoms (e.g., respiratory arrest and wheezing). We observed a higher mortality rate in epinephrine users (34 vs. 5), which was probably due to a delayed administration of epinephrine (in epinephrine users, 56% of the death cases experienced respiratory or cardiac arrest prior to epinephrine administration, and 47% of the death cases did not receive epinephrine as the initial treatment). This demonstrated the importance of early use of epinephrine for severe anaphylactic patients. Although the rate of use of antihistamines was not high (28.9%), the use of corticosteroids was considerable (977 of 1,189; 82.2%). Among the patients who received corticosteroids, the number of patients who received corticosteroids as a first-line treatment was substantial (904 of 977; 92.5%). The importance of a timely administration of epinephrine should be stressed in DIA management.

Assessment of the Epinephrine Administration Route

There is significant discrepancy between guidelines [2,3] and actual practice in the Beijing region regarding the administration route of epinephrine. Based on a previous pharmacokinetic study in children not experiencing anaphylaxis, IM injection of epinephrine into the anterolateral thigh results in a higher and more rapid peak plasma concentration compared to SC injection in the arm [35], and thus IM should be the preferred administration route [3]. However, more patients in our study received SC epinephrine compared to IM administration (31.5 vs. 16.9%). IV continuous infusion of epinephrine should only be given to patients not responding to IM injection [3]. Nevertheless, our data showed that in 8.1% of cases the initial administration route of epinephrine was by continuous infusion. A possible explanation is that physicians' lack of knowledge regarding anaphylaxis treatment guidelines contributes to a high utilization of the IV route of administration. IV bolus administration of epinephrine should be avoided whenever possible due to the risk of cardiac arrhythmias and the increased potential for inappropriate dosing [19,36,37,38]. It should only be considered when a patient is experiencing an actual or impending cardiovascular collapse and is unresponsive to an epinephrine continuous infusion or when an epinephrine continuous infusionis not feasible due to time constraints [20]. However, our data showed that IV bolus injection was the most frequently (43.5%) used initial administration route; it was used about 5.4 times more than the IV continuous infusion route (8.1%). The data showed that there was no statistically significant relationship between the severity of the anaphylaxis and the treatment administration route selected. In this analysis, we excluded patients with cardiac or respiratory arrest prior to administration of epinephrine, since the route and dose of epinephrine should follow the guidelines for resuscitations. Furthermore, a relatively low proportion of perioperative cases could not account for the highly frequent choice of the IV route. The data support a need for further education of clinicians regarding the appropriate route of epinephrine administration in the management of anaphylaxis.

Implications of Overdosing of Epinephrine and CAE

The observation of the significantly higher risk of overdose subsequent to IV bolus administration of epinephrine is consistent with prior research [19]. Our finding of a significantly higher risk of cardiovascular complications associated with IV bolus injection compared to IM administration confirms the relative safety of IM administration reported by Campbell et al. [19]. Excluding patients with multiple presentations of CAE, 12 of the 15 patients (80%) who developed adverse CAE were in the overdose group, suggestingthat bolus administration of IV epinephrine is associated with inappropriate dosing [19,35,36,37,38].

Limitations

Our retrospective analysis was based on self-reported cases by health care professionals to the BPD database, and therefore our study has the following limitations: (1) we could not assess the prevalence of anaphylaxis in the region studied as we did not have information for the total patient base, (2) reporting biases may exist (most reported cases were hospitalized patients in the non-ED setting, and only severe anaphylactic cases may have been reported), (3) we may not have included all DIA patients in the BPD (cases were missed if clinicians did not report using terms related to allergy or anaphylaxis or hypersensitivity; e.g., a patient had bronchospasm, wheeze, and vomiting but was not described as “allergy” by clinicians when reporting to the BPD, and some reported cases were not included due to a lack of sufficient information), and (4) the causative drugs were identified using WHO-UMC criteria [15]. The drug hypersensitivity diagnostic workup could increase sensitivity when determining the causative drug for anaphylaxis [39,40,41,42,43]. However, such information was not recorded in the BPD. Despite this, the method we used should be robust against some of the reporting biases; rigorous inclusion/exclusion criteria were utilized and all potential anaphylaxis cases were adjudicated by trained physician/allergists, and only patients with confirmed anaphylaxis and a complete data record were included in the analysis.

Our study suggests that epinephrine use in DIA management in Beijing should be improved. Underuse of epinephrine, overuse of IV bolus administration, and overdosing of epinephrine are the 3 major problems. Our results highlight the risk of overdosing and CAE associated with IV bolus administration. Targeted educational programs on the utilization of consensus anaphylaxis management guidelines for optimal patient care are necessary.

Til Stürmer received investigator-initiated research funding and support as principal investigator (R01/R56 AG023178) from the National Institute on Aging (NIA), and as coinvestigator (R01 CA174453, R01 HL118255, and R21-HD080214) from the National Institutes of Health (NIH). He also receives salary support as director of the Comparative Effectiveness Research (CER) Strategic Initiative from the NC TraCS Institute, he is a recipient of the UNC Clinical and Translational Science Award (UL1TR001111), and he receives support as director of the Center for Pharmacoepidemiology (current members: GlaxoSmithKline, UCB BioSciences, and Merck) and research support from pharmaceutical companies (Amgen and AstraZeneca) to the Department of Epidemiology, University of North Carolina at Chapel Hill. Dr. Stürmer does not accept personal compensation of any kind from any pharmaceutical company. He owns stock in Novartis, Roche, BASF, AstraZeneca, and Novo Nordisk. The remaining authors have no conflict of interests to disclose. This research received no funding from any funding agency in the public, commercial, or not-for-profit sectors.

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Tiansheng Wang and Xiang Ma contributed equally to this work.

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