Combining Super Learner with high-dimensional propensity score to improve confounding adjustment: A real-world application in chronic lymphocytic leukemia.

PURPOSE: High-dimensional propensity score (hdPS) is a semiautomated method that leverages a vast number of covariates available in healthcare databases to improve confounding adjustment. A novel combined Super Learner (SL)-hdPS approach was proposed to assist with selecting the number of covariates for propensity score inclusion, and was found in plasmode simulation studies to improve bias reduction and precision compared to hdPS alone. However, the approach has not been examined in the applied setting. METHODS: We compared SL-hdPS's performance with that of several hdPS models, each with prespecified covariates and a different number of empirically-identified covariates, using a cohort study comparing real-world bleeding rates between ibrutinib- and bendamustine-rituximab (BR)-treated individuals with chronic lymphocytic leukemia in Optum's de-identified Clinformatics® Data Mart commercial claims database (2013-2020). We used inverse probability of treatment weighting for confounding adjustment and Cox proportional hazards regression to estimate hazard ratios (HRs) for bleeding outcomes. Parameters of interest included prespecified and empirically-identified covariate balance (absolute standardized difference [ASD] thresholds of <0.10 and <0.05) and outcome HR precision (95% confidence intervals). RESULTS: We identified 2423 ibrutinib- and 1102 BR-treated individuals. Including >200 empirically-identified covariates in the hdPS model compromised covariate balance at both ASD thresholds. SL-hdPS balanced more covariates than all individual hdPS models at both ASD thresholds. The bleeding HR 95% confidence intervals were generally narrower with SL-hdPS than with individual hdPS models. CONCLUSION: In a real-world application, hdPS was sensitive to the number of covariates included, while use of SL for covariate selection resulted in improved covariate balance and possibly improved precision.

Breaking Research Silos and Stimulating "Innovation at the Edges" in Epidemiology.

Epidemiological training often requires specialization in a subdiscipline (e.g., pharmacoepidemiology, genetic epidemiology, social epidemiology, or infectious disease epidemiology). While specialization is necessary and beneficial, it comes at the cost of decreased awareness of scientific developments in other subdisciplines of epidemiology. In this commentary, we argue for the importance of promoting an exchange of ideas across seemingly disparate epidemiologic subdisciplines. Such an exchange can lead to invaluable opportunities to learn from and merge knowledge across subdisciplines. It can promote "innovation at the edges," a process of borrowing and transforming methods from one subdiscipline in order to develop something new and advance another subdiscipline. Further, we outline specific actionable steps at the researcher, institution, and professional society level that can promote such innovation.

Evaluating the Impact of a Pharmacist-Led Antimicrobial Stewardship Intervention at Discharge in a Community, Nonteaching Hospital.

INTRODUCTION: Approximately 30% to 50% of hospital discharge antimicrobials are inappropriate. Limited data exist on approaches to improve antimicrobial prescribing practices at the time of discharge from a community hospital. Objective: To assess the impact of a comprehensive pharmacist-led antimicrobial stewardship intervention at discharge. METHODS: We conducted a quasi-experimental, pre-post study. A biphasic intervention took place on 2 medicine units from November 2019 to May 2020 at a community hospital. Baseline data were collected, followed by prescriber education on antimicrobial stewardship to both units (education phase). Next, a pharmacist-led intervention took place on one unit (intervention phase). The primary outcome was composite appropriateness of an oral antimicrobial prescribed to an adult at the time of discharge, defined by narrow spectrum of activity, dosing, and duration of therapy. The primary outcome was assessed using Fisher exact test. RESULTS: Baseline composite appropriateness was 30% (n = 12) on the control unit and 30.8% (n = 20) on the intervention unit. From baseline to posteducation, no significant change in composite appropriateness was found on the control (30% to 26.7%, P = 0.256) or intervention (30.8% to 19.4%, P = 0.09) unit. There was no significant difference between the education to intervention phase (26.7% vs 35%, P = 0.254) on the control unit. On the intervention unit, a significant difference in composite appropriateness was found from the education to intervention phase (19.4% vs 47.8%, P = 0.017). CONCLUSION AND RELEVANCE: A pharmacist-led intervention improved appropriateness of oral antimicrobials prescribed at discharge. One-time education was insufficient for improving antimicrobial stewardship.

Risk for Recurrent Venous Thromboembolism and Bleeding With Apixaban Compared With Rivaroxaban: An Analysis of Real-World Data.

BACKGROUND: Apixaban and rivaroxaban are replacing vitamin K antagonists for the treatment of venous thromboembolism (VTE) in adults; however, head-to-head comparisons remain limited. OBJECTIVE: To assess the effectiveness and safety of apixaban compared with rivaroxaban in patients with VTE. DESIGN: Retrospective new-user cohort study. SETTING: U.S.-based commercial health care insurance database from 1 January 2015 to 30 June 2020. PARTICIPANTS: Adults with VTE who were newly prescribed apixaban or rivaroxaban. MEASUREMENTS: The primary effectiveness outcome was recurrent VTE, a composite of deep venous thrombosis and pulmonary embolism. The primary safety outcome was a composite of gastrointestinal and intracranial bleeding. RESULTS: Of 49 900 eligible patients with VTE, 18 618 were new users of apixaban and 18 618 were new users of rivaroxaban. Median follow-up was 102 days (25th, 75th percentiles: 30, 128 days) among apixaban and 105 days (25th, 75th percentiles: 30, 140 days) among rivaroxaban users. After propensity score matching, apixaban (vs. rivaroxaban) was associated with a lower rate for recurrent VTE (hazard ratio, 0.77 [95% CI, 0.69 to 0.87]) and bleeding (hazard ratio, 0.60 [CI, 0.53 to 0.69]). The absolute reduction in the probability of recurrent VTE with apixaban versus rivaroxaban was 0.006 (CI, 0.005 to 0.011) within 2 months and 0.011 (CI, 0.011 to 0.013) within 6 months of initiation. The absolute reduction in the probability of gastrointestinal and intracranial bleeding with apixaban versus rivaroxaban was 0.011 (CI, 0.010 to 0.011) within 2 months and 0.015 (CI, 0.013 to 0.015) within 6 months of initiation. LIMITATION: Short follow-up. CONCLUSION: In this population-based cohort study, patients with VTE who were new users of apixaban had lower rates for recurrent VTE and bleeding than new users of rivaroxaban. PRIMARY FUNDING SOURCE: None.

Skeletal muscle relaxant drug-drug-drug interactions and unintentional traumatic injury: Screening to detect three-way drug interaction signals.

AIM: The aim of this study was to identify skeletal muscle relaxant (SMR) drug-drug-drug interaction (3DI) signals associated with increased rates of unintentional traumatic injury. METHODS: We conducted automated high-throughput pharmacoepidemiologic screening of 2000-2019 healthcare data for members of United States commercial and Medicare Advantage health plans. We performed a self-controlled case series study for each drug triad consisting of an SMR base-pair (i.e., concomitant use of an SMR with another medication), and a co-dispensed medication (i.e., candidate interacting precipitant) taken during ongoing use of the base-pair. We included patients aged ≥16 years with an injury occurring during base-pair-exposed observation time. We used conditional Poisson regression to calculate adjusted rate ratios (RRs) with 95% confidence intervals (CIs) for injury with each SMR base-pair + candidate interacting precipitant (i.e., triad) versus the SMR-containing base-pair alone. RESULTS: Among 58 478 triads, 29 were significantly positively associated with injury; confounder-adjusted RRs ranged from 1.39 (95% CI = 1.01-1.91) for tizanidine + omeprazole with gabapentin to 2.23 (95% CI = 1.02-4.87) for tizanidine + diclofenac with alprazolam. Most identified 3DI signals are new and have not been formally investigated. CONCLUSION: We identified 29 SMR 3DI signals associated with increased rates of injury. Future aetiologic studies should confirm or refute these SMR 3DI signals.

Self-controlled assessment of thromboembolic event (TEE) risk following intravenous immune globulin (IGIV) in the U.S. (2006-2012).

Since 2013, the U.S. Food and Drug administration (FDA) has required that intravenous immune globulin (IGIV) products carry a boxed warning concerning the risk of thromboembolic events (TEEs). This study assessed the incidence of TEEs attributable to IGIV in a large population-based cohort. A self-controlled risk interval design was used to quantify the transient increase in TEE risk during the risk interval (days 0-2 and 0-13 following IGIV for arterial and venous TEEs, respectively) relative to a later control interval (days 14-27 following IGIV). Potential IGIV-exposed TEE cases from 2006 to 2012 were identified from the FDA-sponsored Sentinel Distributed Database and confirmed through medical record review. Inpatient IGIV exposures were not included in the venous TEE analysis due to concerns about time-varying confounding. 19,069 new users of IGIV who received 93,555 treatment episodes were included. Charts were retrieved for 62% and 70% of potential venous and arterial cases, respectively. There was a transient increase in the risk of arterial TEEs during days 0-2 following IGIV treatment (RR = 4.69; 95% CI 1.87, 11.90; absolute increase in risk = 8.86 events per 10,000 patients, 95% CI 3.25, 14.6), but no significant increase in venous TEE risk during days 0-13 following outpatient IGIV treatments (RR = 1.07, 95% CI 0.34, 3.48). Our results suggest there is a small increase in the absolute risk of arterial TEEs following IGIV. However, lower-than-expected chart retrieval rates and the possibility of time-varying confounding mean that our results should be interpreted cautiously. Continued pharmacovigilance efforts are warranted.

Effectiveness and Safety of Direct Oral Anticoagulants Versus Warfarin in Patients With Valvular Atrial Fibrillation : A Population-Based Cohort Study.

BACKGROUND: Direct oral anticoagulants (DOACs) are increasingly used in place of warfarin, but evidence about their effectiveness and safety in patients with valvular atrial fibrillation (AF) remains limited. OBJECTIVE: To assess the effectiveness and safety of DOACs compared with warfarin in patients with valvular AF. DESIGN: New-user retrospective propensity score-matched cohort study. SETTING: U.S.-based commercial health care database from 1 January 2010 to 30 June 2019. PARTICIPANTS: Adults with valvular AF who were newly prescribed DOACs or warfarin. MEASUREMENTS: The primary effectiveness outcome was a composite of ischemic stroke or systemic embolism. The primary safety outcome was a composite of intracranial or gastrointestinal bleeding. RESULTS: Among a total of 56 336 patients with valvular AF matched on propensity score, use of DOACs (vs. warfarin) was associated with lower risk for ischemic stroke or systemic embolism (hazard ratio [HR], 0.64 [95% CI, 0.59 to 0.70]) and major bleeding events (HR, 0.67 [CI, 0.63 to 0.72]). The results for the effectiveness and safety outcomes remained consistent for apixaban (HRs, 0.54 [CI, 0.47 to 0.61] and 0.52 [CI, 0.47 to 0.57], respectively) and rivaroxaban (HRs, 0.74 [CI, 0.64 to 0.86] and 0.87 [CI, 0.79 to 0.96], respectively); with dabigatran, results were consistent for the major bleeding outcome (HR, 0.81 [CI, 0.68 to 0.97]) but not for effectiveness (HR, 1.03 [CI, 0.81 to 1.31]). LIMITATION: Relatively short follow-up; inability to ascertain disease severity. CONCLUSION: In this comparative effectiveness study using practice-based claims data, patients with valvular AF who were new users of DOACs had lower risks for ischemic stroke or systemic embolism and major bleeding than new users of warfarin. These data may be used to guide risk-benefit discussions regarding anticoagulant choices for patients with valvular AF. PRIMARY FUNDING SOURCE: None.

Thromboembolic Events in Users of Warfarin Treated with Different Skeletal Muscle Relaxants.

Background and Objectives: Warfarin and a skeletal muscle relaxant are co-treatments in nearly a quarter-million annual United States (US) office visits. Despite international calls to minimize patient harm arising from anticoagulant drug interactions, scant data exist on clinical outcomes in real-world populations. We examined effects of concomitant use of warfarin and individual muscle relaxants on rates of hospitalization for thromboembolism among economically disadvantaged persons. Materials and Methods: Using 1999−2012 administrative data of four US state Medicaid programs, we conducted 16 retrospective self-controlled case series studies: half included concomitant users of warfarin + one of eight muscle relaxants; half included concomitant users of an inhaled corticosteroid (ICS) + one of eight muscle relaxants. The ICS analyses served as negative control comparisons. In each study, we calculated incidence rate ratios (IRRs) comparing thromboembolism rates in the co-exposed versus warfarin/ICS-only exposed person-time, adjusting for time-varying confounders. Results: Among ~70 million persons, we identified 8693 warfarin-treated subjects who concomitantly used a muscle relaxant, were hospitalized for thromboembolism, and met all other inclusion criteria. Time-varying confounder-adjusted IRRs ranged from 0.31 (95% confidence interval: 0.13−0.77) for metaxalone to 3.44 (95% confidence interval: 1.53−7.78) for tizanidine. The tizanidine finding was robust after quantitatively adjusting for negative control ICS findings, and in numerous prespecified secondary analyses. Conclusions: We identified a potential >3-fold increase in the rate of hospitalized thromboembolism in concomitant users of warfarin + tizanidine vs. warfarin alone. Alternative explanations for this finding include confounding by indication, a native effect of tizanidine, or chance.

Preoperative Sedative-hypnotic Medication Use and Adverse Postoperative Outcomes.

OBJECTIVE: To determine the association between preoperative benzodiazepine and nonbenzodiazepine receptor agonist ("Z-drugs") use and adverse outcomes after surgery. BACKGROUND: Prescriptions for benzodiazepines and Z-drugs have increased over the past decade. Despite this, the association of preoperative benzodiazepines and Z-drug receipt with adverse outcomes after surgery is unknown. METHODS: Using the Optum Clinformatics Datamart, we performed a retrospective cohort study of adults 18 years or older who underwent any of 10 common surgical procedures between 2010 and 2015. The principal exposure was one or more filled prescriptions for a benzodiazepine or Z-drug in the 90 days before surgery. The primary outcome was any emergency department visit or hospital admission for either (1) a drug related adverse medical event or overdose or (2) a traumatic injury in the 30 days after surgery. RESULTS: Of 785,346 patients meeting inclusion criteria, 94,887 (12.1%) filled a preoperative prescription for a benzodiazepine or Z-drug. From multivariable logistic regression, benzodiazepine or Z-drug use was associated with an increased odds of an adverse postoperative event [odds ratio 1.13; 95% confidence interval: 1.08-1.18). In a separate regression, coprescription of benzodiazepines or Z-drugs with opioids was associated with a 1.45 odds of an adverse postoperative event (95% confidence interval: 1.37-1.53). CONCLUSIONS: Preoperative benzodiazepines and Z-drug use is common and associated with increased odds of adverse outcomes after surgery, particularly when coprescribed with opioids. Counseling on appropriate benzodiazepine and Z-drug use in advance of elective surgery may potentially increase the safety of surgical care.

Cardiovascular and major bleeding outcomes with antiplatelet and direct oral anticoagulants in patients with acute coronary syndrome and atrial fibrillation: A population-based analysis.

BACKGROUND: Direct oral anticoagulants (DOACs) are replacing warfarin for stroke prevention in patients with atrial fibrillation (AF). OBJECTIVE: To assess the effectiveness and safety of concomitant treatment with antiplatelet-DOAC compared to antiplatelet-warfarin in patients with acute coronary syndrome (ACS) and AF. DESIGN: Retrospective propensity score-matched cohort study using United States-based commercial healthcare database from January 2016 to June 2019. PARTICIPANTS: New-users of antiplatelet-DOAC and antiplatelet-warfarin who initiated the combined therapy within 30 days following incident ACS diagnosis. MEASUREMENTS: Primary study outcomes were recurrent cardiovascular diseases (CVD) (ie, a composite of stroke and myocardial infarction) and major bleeding events identified via discharge diagnoses. We controlled for potential confounders via propensity score matching (PSM). We generated marginal hazard ratios (HRs) via Cox proportional hazards regression using a robust variance estimator while adjusting for calendar time. RESULTS: After PSM, a total of 2,472 persons were included (1,236 users of antiplatelet-DOAC and 1,236 users of antiplatelet-warfarin). The use of antiplatelet-DOAC (vs. antiplatelet-warfarin) was associated with a reduced rate of recurrent CVD (adjusted HR 0.72, 95% confidence interval [CI], 0.56-0.92) and major bleeding events (adjusted HR, 0.49, 95% CI 0.33-0.72). LIMITATIONS: Residual confounding. CONCLUSIONS: In real-world data of AF patients with concurrent ACS, the use of antiplatelet-DOAC following ACS diagnosis was associated with a lower rate of recurrent CVD and major bleeding events compared with antiplatelet-warfarin. These findings highlight a potential promising role for DOACs in patients with ACS and AF requiring combined antiplatelet therapy.

Pharmacosafety of fluoroquinolone and macrolide antibiotics in the clinical care of patients with myasthenia gravis.

INTRODUCTION/AIMS: Anecdotal case reports have suggested a potential association of fluoroquinolones and macrolides with myasthenia gravis (MG) exacerbation, prompting warnings against the use of these drugs in this population. However, large-scale and reliable population-based data that demonstrate this association are lacking. This study aims to examine the association between outpatient treatment with fluoroquinolones or macrolides and MG-related hospitalization. METHODS: A retrospective cohort study consisting of adult MG patients was conducted using a large de-identified healthcare claims database. Antibiotic prescription claims were identified, and MG-related hospitalizations were assessed at 15, 30, and 90 days after the date of prescription. We used mixed effects survival regression with log-logistic distribution and independent covariance matrix to estimate odds ratios (ORs) of hospitalization for each potentially exacerbating antibiotic using beta-lactam as the reference and adjusting for covariates. RESULTS: Among 1556 MG patients receiving 894 fluoroquinolone prescriptions, 729 macrolide prescriptions, and 1608 beta-lactam prescriptions during the study period, there was no difference in 15, 30, or 90-day odds of MG-related hospitalization between fluoroquinolone or macrolide users compared to prescribed beta-lactams. However, estimates were higher for fluoroquinolones than macrolides, even after covariate adjustment (adjusted OR [aOR] 4.60, 95% confidence interval [CI] 0.55-38.57 for fluoroquinolones and OR 0.56, 95% CI 0.32-0.97 for macrolides, respectively, at 15 days). DISCUSSION: Fluoroquinolone and macrolide antibiotics are prescribed frequently to patients with MG. While statistical imprecision precludes a definitive conclusion, elevated ORs for fluoroquinolones raise the possibility of an underpowered association that merits further investigation.

Validity of ICD-10-CM diagnoses to identify hospitalizations for serious infections among patients treated with biologic therapies.

PURPOSE: Identifying hospitalizations for serious infections among patients dispensed biologic therapies within healthcare databases is important for post-marketing surveillance of these drugs. We determined the positive predictive value (PPV) of an ICD-10-CM-based diagnostic coding algorithm to identify hospitalization for serious infection among patients dispensed biologic therapy within the FDA's Sentinel Distributed Database. METHODS: We identified health plan members who met the following algorithm criteria: (1) hospital ICD-10-CM discharge diagnosis of serious infection between July 1, 2016 and August 31, 2018; (2) either outpatient/emergency department infection diagnosis or outpatient antimicrobial treatment within 7 days prior to hospitalization; (3) inflammatory bowel disease, psoriasis, or rheumatological diagnosis within 1 year prior to hospitalization, and (4) were dispensed outpatient biologic therapy within 90 days prior to admission. Medical records were reviewed by infectious disease clinicians to adjudicate hospitalizations for serious infection. The PPV (95% confidence interval [CI]) for confirmed events was determined after further weighting by the prevalence of the type of serious infection in the database. RESULTS: Among 223 selected health plan members who met the algorithm, 209 (93.7% [95% CI, 90.1%-96.9%]) were confirmed to have a hospitalization for serious infection. After weighting by the prevalence of the type of serious infection, the PPV of the ICD-10-CM algorithm identifying a hospitalization for serious infection was 80.2% (95% CI, 75.3%-84.7%). CONCLUSIONS: The ICD-10-CM-based algorithm for hospitalization for serious infection among patients dispensed biologic therapies within the Sentinel Distributed Database had 80% PPV for confirmed events and could be considered for use within pharmacoepidemiologic studies.

Knowledge of biosimilars and perceptions of the naming conventions for biosimilar products in clinical practice in the United States.

BACKGROUND: Biosimilar therapies and their naming conventions are both relatively new to the drug development market and in clinical practice. We studied the use of the four-letter naming convention in practice and the knowledge, perceptions, and preferences of US health care providers. METHODS: A survey was distributed among health care professionals with a history of utilizing biosimilars in clinical practice to measure key knowledge and the presence of discernable naming trends. Differences in responses across pre-hypothesized subgroups were tested for statistical significance. RESULTS: Of the 506 surveys emailed, 83 (16%) people responded. Overall, there was poor knowledge about the key concepts surrounding biosimilars. For example, only 52% of respondents correctly identified that biosimilars were not the same as the generic drug; however, frequent use correlated with superior knowledge across all groups. In reference to naming preferences, 67% of all respondents indicated that they commonly use the brand name to distinguish biosimilars in clinical practice and a majority of them (85%) indicated that the brand name was easier to remember than the nonproprietary name with the four-letter suffix. An unexpected number of neutral responses was documented. Notably, more than half of respondents (68%) indicated a neutral response when asked if the four-letter suffix promoted medical errors. CONCLUSIONS: There remains a knowledge gap with regard to biosimilars, and lack of consensus on how the naming convention is and should be utilized in clinical practice. The data also suggest that effective biosimilar education could aid in promoting familiarity with the naming convention among health care providers.

The risk of sudden cardiac arrest and ventricular arrhythmia with rosiglitazone versus pioglitazone: real-world evidence on thiazolidinedione safety.

BACKGROUND: The low cost of thiazolidinediones makes them a potentially valuable therapeutic option for the > 300 million economically disadvantaged persons worldwide with type 2 diabetes mellitus. Differential selectivity of thiazolidinediones for peroxisome proliferator-activated receptors in the myocardium may lead to disparate arrhythmogenic effects. We examined real-world effects of thiazolidinediones on outpatient-originating sudden cardiac arrest (SCA) and ventricular arrhythmia (VA). METHODS: We conducted population-based high-dimensional propensity score-matched cohort studies in five Medicaid programs (California, Florida, New York, Ohio, Pennsylvania | 1999-2012) and a commercial health insurance plan (Optum Clinformatics | 2000-2016). We defined exposure based on incident rosiglitazone or pioglitazone dispensings; the latter served as an active comparator. We controlled for confounding by matching exposure groups on propensity score, informed by baseline covariates identified via a data adaptive approach. We ascertained SCA/VA outcomes precipitating hospital presentation using a validated, diagnosis-based algorithm. We generated marginal hazard ratios (HRs) via Cox proportional hazards regression that accounted for clustering within matched pairs. We prespecified Medicaid and Optum findings as primary and secondary, respectively; the latter served as a conceptual replication dataset. RESULTS: The adjusted HR for SCA/VA among rosiglitazone (vs. pioglitazone) users was 0.91 (0.75-1.10) in Medicaid and 0.88 (0.61-1.28) in Optum. Among Medicaid but not Optum enrollees, we found treatment effect heterogeneity by sex (adjusted HRs = 0.71 [0.54-0.93] and 1.16 [0.89-1.52] in men and women respectively, interaction term p-value = 0.01). CONCLUSIONS: Rosiglitazone and pioglitazone appear to be associated with similar risks of SCA/VA.

Twelve-year trends in pharmacologic treatment of type 2 diabetes among patients with heart failure in the United States.

We conducted a cross-sectional analysis using a database from commercial health plans in the United States to describe trends in the use of antidiabetic medications among patients with type 2 diabetes and heart failure (HF) from 2006 through 2017. We used loop diuretic dose as a surrogate for HF severity (mild HF 0-40 mg/day, moderate-severe HF >40 mg/day). We assessed antidiabetic medication dispensing in the 90 days following HF diagnosis. Over the 12-year period, we identified an increase in the use of metformin (39.2% vs. 62.6%), dipeptidyl peptidase-4 inhibitors (DPP-4i) (0.5% vs. 17.1%) and sodium-glucose co-transporter-2 inhibitors (SGLT-2i) (0.0% vs. 9.0%), but a decrease in the use of sulphonylureas (47.8% vs. 27.8%) and thiazolidinediones (TZDs) (31.7% vs. 5.3%). In 2017, patients with moderate-severe HF more commonly used insulin (43.1%); a majority of mild HF patients used metformin (62.8%). A proportion of patients with moderate-severe HF used TZDs (4.4%). Among patients with diabetes and HF, the use of metformin and DPP-4i rapidly increased, but a proportion of patients with moderate-severe HF continued to use TZDs. Despite their promising cardiovascular safety profile, SGLT-2i use remains limited.

Does hospitalization for thromboembolism improve oral anticoagulant adherence in patients with atrial fibrillation?

BACKGROUND: It is not known how medication adherence changes after hospitalization for a sentinel thromboembolic event. OBJECTIVE: The purpose of this study was to examine the impact of hospitalization for ischemic stroke or thromboembolism on postdischarge adherence to oral anticoagulants in patients with atrial fibrillation. METHODS: We conducted a quasi-experimental pre-post observational study using a large U.S. commercial insurance health care claims database. Adult patients with atrial fibrillation taking oral anticoagulants with a random hospitalization for a nonbleeding-related reason occurring after the first observed oral anticoagulant prescription fill, with no other admissions within the preceding and following 6 months, were identified in Optum Clinformatics (Eden Prairie, MN) from 2009 to 2016. Adherence was estimated by the proportion of days covered within 6 and 12 months before and after hospitalization. Difference-in-difference analysis using a generalized linear model was employed to compare pre- and post-hospitalization proportions of days covered (PDCs) by reasons for hospitalization (i.e., ischemic stroke or thromboembolism vs. other nonbleeding-related reasons), adjusting for imbalanced baseline characteristics. RESULTS: Of the 21,400 individuals meeting inclusion criteria, 5.4% were hospitalized for ischemic stroke or thromboembolism and 94.6% for other nonbleeding-related reasons. Baseline characteristics were quite similar between groups, except for a few covariables such as age or CHA2DS2-VASc score. Minority race or ethnicity individuals had 0.7% lower overall PDC than whites (P = 0.006). After covariate adjustment, 6-month adherence declined by 1.1% less in individuals hospitalized for ischemic stroke or thromboembolism, compared with other nonbleeding reasons, although the difference was not statistically significant (P = 0.17). Similar results were observed for the 12-month window. CONCLUSION: This real-world study suggests that more effective strategies are needed to improve adherence to oral anticoagulant, particularly after a thromboembolic event.

Comparative risk of serious hypoglycemia with oral antidiabetic monotherapy: A retrospective cohort study.

PURPOSE: To examine and compare risks of serious hypoglycemia among antidiabetic monotherapy-treated adults receiving metformin, a sulfonylurea, a meglitinide, or a thiazolidinedione. METHODS: We performed a retrospective cohort study of apparently new users of monotherapy with metformin, glimepiride, glipizide, glyburide, pioglitazone, rosiglitazone, nateglinide, or repaglinide within a dataset of Medicaid beneficiaries from California, Florida, New York, Ohio, and Pennsylvania. We did not include users of dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 agonists, or sodium-glucose co-transporter 2 inhibitors. We identified serious hypoglycemia outcomes within 180 days following new use using a validated, diagnosis-based algorithm. We calculated age- and sex-standardized outcome occurrence rates for each drug and generated propensity score-adjusted hazard ratios vs metformin using Cox proportional hazards regression. RESULTS: The ranking of standardized occurrence rates of serious hypoglycemia was glyburide > glimepiride > glipizide > repaglinide > nateglinide > rosiglitazone > pioglitazone > metformin. Rates were increased for all study drugs at higher average daily doses. Adjusted hazard ratios (95% confidence intervals) vs metformin were 3.95 (3.66-4.26) for glyburide, 3.28 (2.98-3.62) for glimepiride, 2.57 (2.38-2.78) for glipizide, 2.03 (1.64-2.52) for repaglinide, 1.21 (0.89-1.66) for nateglinide, 0.90 (0.75-1.07) for rosiglitazone, and 0.80 (0.68-0.93) for pioglitazone. CONCLUSIONS: Sulfonylureas were associated with the highest rates of serious hypoglycemia. Among all study drugs, the highest rate was seen with glyburide. Pioglitazone was associated with a lower adjusted hazard for serious hypoglycemia vs metformin, while rosiglitazone and nateglinide had hazards similar to that of metformin.

Evaluation of the US Food and Drug Administration sentinel analysis tools in confirming previously observed drug-outcome associations: The case of clindamycin and Clostridium difficile infection.

PURPOSE: The Food and Drug Administration's Sentinel System developed parameterized, reusable analytic programs for evaluation of medical product safety. Research on outpatient antibiotic exposures, and Clostridium difficile infection (CDI) with non-user reference groups led us to expect a higher rate of CDI among outpatient clindamycin users vs penicillin users. We evaluated the ability of the Cohort Identification and Descriptive Analysis and Propensity Score Matching tools to identify a higher rate of CDI among clindamycin users. METHODS: We matched new users of outpatient dispensings of oral clindamycin or penicillin from 13 Data Partners 1:1 on propensity score and followed them for up to 60 days for development of CDI. We used Cox proportional hazards regression stratified by Data Partner and matched pair to compare CDI incidence. RESULTS: Propensity score models at 3 Data Partners had convergence warnings and a limited range of predicted values. We excluded these Data Partners despite adequate covariate balance after matching. From the 10 Data Partners where these models converged without warnings, we identified 807 919 new clindamycin users and 8 815 441 new penicillin users eligible for the analysis. The stratified analysis of 807 769 matched pairs included 840 events among clindamycin users and 290 among penicillin users (hazard ratio 2.90, 95% confidence interval 2.53, 3.31). CONCLUSIONS: This evaluation produced an expected result and identified several potential enhancements to the Propensity Score Matching tool. This study has important limitations. CDI risk may have been related to factors other than the inherent properties of the drugs, such as duration of use or subsequent exposures.

Chart validation of inpatient ICD-9-CM administrative diagnosis codes for acute myocardial infarction (AMI) among intravenous immune globulin (IGIV) users in the Sentinel Distributed Database.

BACKGROUND: The Sentinel Distributed Database (SDD) is a large database of patient-level administrative health care records, primarily derived from insurance claims and electronic health records, and is sponsored by the US Food and Drug Administration for medical product safety evaluations. Acute myocardial infarction (AMI) is a common study endpoint for drug safety studies that rely on health records from the SDD and other administrative databases. PURPOSE: In this chart validation study, we report on the positive predictive value (PPV) of inpatient International Classification of Diseases, Ninth Revision, Clinical Modification AMI administrative diagnosis codes (410.x1 and 410.x0) in the SDD. METHODS: As part of an assessment of thromboembolic adverse event risk following treatment with intravenous immune globulin, charts were obtained for 103 potential post-intravenous immune globulin AMI cases. Charts were abstracted by trained nurses and physician-adjudicated based on prespecified diagnostic criteria. RESULTS: Acute myocardial infarction status could be determined for 89 potential cases. The PPVs for the inpatient AMI diagnoses recorded in the SDD were 75% overall (95% CI, 65-84%), 93% (95% CI, 78-99%) for principal-position diagnoses, 88% (95% CI, 72-97%) for secondary diagnoses, and 38% (95% CI, 20-59%) for position-unspecified diagnoses (eg, diagnoses originating from separate physician claims associated with an inpatient stay). Of the confirmed AMI cases, demand ischemia was the suspected etiology more often for those coded in secondary or unspecified positions (72% and 40%, respectively) than for principal-position AMI diagnoses (21%). CONCLUSIONS: The PPVs for principal and secondary AMI diagnoses were high and similar to estimates from prior chart validation studies. Position-unspecified diagnosis codes were less likely to represent true AMI cases.