A computer case definition for sudden cardiac death

Association of antipsychotic formulations with sudden cardiac death in patients with schizophrenia: A nationwide population-based case-control study

The aim of this study was to clarify the association between various antipsychotic formulations-oral-daily antipsychotics (OAPs), long-acting injectable antipsychotics (LAIs), and their combination-and the risk of sudden cardiac death (SCD). We conducted a nationwide population-based case-control study using data from 2011 to 2020 from the National Health Insurance Research Database and multiple-cause-of-death data from Taiwan. The study included patients with a new diagnosis of schizophrenia who were followed for SCD occurrence until 2020. Cases and controls were frequency-matched at a 1:4 ratio by age, sex, and year of new schizophrenia diagnosis. Compared with the use of OAP monotherapy, the use of LAI and OAP combination (OR = 1.91) and LAI monotherapy (OR = 1.45) were associated with an increased risk of SCD. Additionally, cardiovascular comorbidities (adjusted OR = 11.15) were identified as a significant risk factor for SCD. This study revealed the following hierarchy of SCD risk associated with antipsychotic formulations (listed from lowest to highest risk): nonuse of antipsychotics, OAP monotherapy, LAI monotherapy, and their combination. These findings underscore the importance of assessing cardiovascular disease history before LAIs are prescribed to patients with schizophrenia and indicate that physicians should avoid prescribing combined antipsychotics when using LAIs.

The Risk of Ventricular Dysrhythmia or Sudden Death in Patients Receiving Serotonin Reuptake Inhibitors With Methadone: A Population-Based Study

Background: Methadone is associated with ventricular dysrhythmias and sudden death. Serotonin reuptake inhibitors (SRIs) may increase the risk of these events either by inhibiting metabolism of methadone’s proarrhythmic (S)-enantiomer, additive QT interval prolongation, or both. We sought to determine whether certain SRIs were associated with a higher risk of methadone-related ventricular dysrhythmias or sudden death.

Methods: We conducted a nested case-control study of Ontario residents receiving methadone between April 1, 1996 and December 31, 2017. Cases, defined as patients who died of sudden cardiac death or were hospitalized with a ventricular dysrhythmia while on methadone, were matched with up to four controls who also received methadone on age, sex, and a disease risk score. We determined the odds ratio (OR) and p-value functions for the association between methadone-related cardiotoxicity and treatment with SRIs known to inhibit metabolism of (S)-methadone (paroxetine, fluvoxamine, sertraline) or prolong the QT interval (citalopram and escitalopram). Patients who were not treated with an SRI served as the reference group.

Results: During the study period, we identified 626 cases and 2,299 matched controls. Following multivariable adjustment, we found that recent use of sertraline, fluvoxamine or paroxetine (adjusted OR 1.30; 95% confidence intervals [CI] 0.90–1.86) and citalopram and escitalopram (adjusted OR 1.26; 95% CI 0.97–1.63) were associated with small increases in the risk methadone-related cardiac toxicity, an assertion supported by the corresponding p-value functions.

Interpretation: Certain SRIs may be associated with a small increase in cardiac toxicity in methadone-treated patients.

Harmonization of the definition of sudden cardiac death in longitudinal cohorts of the European Sudden Cardiac Arrest network - towards Prevention, Education, and New Effective Treatments (ESCAPE-NET) consortium

BACKGROUND

The burden of sudden cardiac death (SCD) in the general population is substantial and SCD frequently occurs among people with few or no known risk factors for cardiac disease. Reported incidences of SCD vary due to differences in definitions and methodology between cohorts. This study aimed to develop a method for adjudicating SCD cases in research settings and to describe uniform case definitions of SCD in an international consortium harmonizing multiple longitudinal study cohorts.

METHODS

The harmonized SCD definitions include both case definitions using data from multiple sources (eg, autopsy reports, medical history, eyewitnesses) as well as a method using only information from registers (eg, cause of death registers, ICD-10 codes). Validation of the register-based method was done within the consortium using the multiple sources definition as gold standard and presenting sensitivity, specificity, accuracy and positive predictive value.

RESULTS

Consensus definitions of "definite," "possible" and "probable" SCD for longitudinal study cohorts were reached. The definitions are based on a stratified approach to reflect the level of certainty of diagnosis and degree of information. The definitions can be applied to both multisource and register-based methods. Validation of the method using register-information in a cohort comprising 1335 cases yielded a sensitivity of 74%, specificity of 88%, accuracy of 86%, and positive predictive value of 54%.

CONCLUSIONS

This study demonstrated that a harmonization of SCD classification across different methodological approaches is feasible. The developed classification can be used to study SCD in longitudinal cohorts and to merge cohorts with different levels of information.

Readmission for cardiac and non-cardiac causes among adults with epilepsy or multiple sclerosis - A nationwide analysis

PURPOSE

The aim of this study was to determine proportions of 30-day cardiac readmissions in adults with epilepsy compared to multiple sclerosis (MS) or those with neither condition. Predictors and causes of readmissions were also examined.

METHODS

We used the 2014 Nationwide Readmissions Database and ICD-9-CM codes to identify people with epilepsy, MS, and without epilepsy or MS. Multinomial logistic regressions were fitted to: (1) examine association between 30-day readmissions and epilepsy, MS or neither, and (2) to describe causes and predictors of 30-day readmission for cardiac readmissions in epilepsy.

RESULTS

Out of 6,870,508 adults admitted in 2014, 202,938 (2.98%) had epilepsy and 29,556 (0.45%) had MS. The proportion of 30-day readmission for epilepsy and MS were, respectively: (1) due to cardiac causes (0.17% vs. 0.13%); (2) due to other causes (13.89% vs. 10.61%). The odds of 30-day cardiac readmission in those with epilepsy and MS were lower compared to those without either condition (OR = 0.64, 95% CI 0.57-0.73, p < 0.0001; OR = 0.60, 95% CI 0.43-0.84, p = 0.003). Among those with epilepsy, increasing age (OR = 1.03, 95% CI 1.02-1.04, p < 0.0001) and a Charlson comorbidity index ≥1 (OR = 1.79, 95% CI 1.24-2.60, p = 0.002) were associated with higher odds of 30-day cardiac readmission. A higher proportion of those with epilepsy readmitted within 30-days due to cardiac causes died in hospital (10.09%) compared to those with MS (not reportable due to cell frequency <10) or without epilepsy or MS (5.61%).

CONCLUSION

Those admitted to a hospital and living with epilepsy had a higher proportion of cardiac readmissions and death in hospital when compared to those living with MS, and the determinants are likely multifactorial. These findings are important and need to be further explored to identify strategies to prevent readmissions due to any cause and treatments that could reduce mortality.

Mortality and concurrent use of opioids and hypnotics in older patients: A retrospective cohort study

BACKGROUND

Benzodiazepine hypnotics and the related nonbenzodiazepine hypnotics (z-drugs) are among the most frequently prescribed medications for older adults. Both can depress respiration, which could have fatal cardiorespiratory effects, particularly among patients with concurrent opioid use. Trazodone, frequently prescribed in low doses for insomnia, has minimal respiratory effects, and, consequently, may be a safer hypnotic for older patients. Thus, for patients beginning treatment with benzodiazepine hypnotics or z-drugs, we compared deaths during periods of current hypnotic use, without or with concurrent opioids, to those for comparable patients receiving trazodone in doses up to 100 mg.

METHODS AND FINDINGS

The retrospective cohort study in the United States included 400,924 Medicare beneficiaries 65 years of age or older without severe illness or evidence of substance use disorder initiating study hypnotic therapy from January 2014 through September 2015. Study endpoints were out-of-hospital (primary) and total mortality. Hazard ratios (HRs) were adjusted for demographic characteristics, psychiatric and neurologic disorders, cardiovascular and renal conditions, respiratory diseases, pain-related diagnoses and medications, measures of frailty, and medical care utilization in a time-dependent propensity score-stratified analysis. Patients without concurrent opioids had 32,388 person-years of current use, 260 (8.0/1,000 person-years) out-of-hospital and 418 (12.9/1,000) total deaths for benzodiazepines; 26,497 person-years,150 (5.7/1,000) out-of-hospital and 227 (8.6/1,000) total deaths for z-drugs; and 16,177 person-years,156 (9.6/1,000) out-of-hospital and 256 (15.8/1,000) total deaths for trazodone. Out-of-hospital and total mortality for benzodiazepines (respective HRs: 0.99 [95% confidence interval, 0.81 to 1.22, p = 0.954] and 0.95 [0.82 to 1.14, p = 0.513] and z-drugs (HRs: 0.96 [0.76 to 1.23], p = 0.767 and 0.87 [0.72 to 1.05], p = 0.153) did not differ significantly from that for trazodone. Patients with concurrent opioids had 4,278 person-years of current use, 90 (21.0/1,000) out-of-hospital and 127 (29.7/1,000) total deaths for benzodiazepines; 3,541 person-years, 40 (11.3/1,000) out-of-hospital and 64 (18.1/1,000) total deaths for z-drugs; and 2,347 person-years, 19 (8.1/1,000) out-of-hospital and 36 (15.3/1,000) total deaths for trazodone. Out-of-hospital and total mortality for benzodiazepines (HRs: 3.02 [1.83 to 4.97], p < 0.001 and 2.21 [1.52 to 3.20], p < 0.001) and z-drugs (HRs: 1.98 [1.14 to 3.44], p = 0.015 and 1.65 [1.09 to 2.49], p = 0.018) were significantly increased relative to trazodone; findings were similar with exclusion of overdose deaths or restriction to those with cardiovascular causes. Limitations included composition of the study cohort and potential confounding by unmeasured variables.

CONCLUSIONS

In US Medicare beneficiaries 65 years of age or older without concurrent opioids who initiated treatment with benzodiazepine hypnotics, z-drugs, or low-dose trazodone, study hypnotics were not associated with mortality. With concurrent opioids, benzodiazepines and z-drugs were associated with increased out-of-hospital and total mortality. These findings indicate that the dangers of benzodiazepine-opioid coadministration go beyond the documented association with overdose death and suggest that in combination with opioids, the z-drugs may be more hazardous than previously thought.

Identification and Validation of Major Cardiovascular Events in the United Kingdom Data Sources Included in a Multi-database Post-authorization Safety Study of Prucalopride

INTRODUCTION

A multinational post-authorization safety study assessed cardiovascular safety in initiators of prucalopride for chronic constipation compared with a matched cohort of polyethylene glycol 3350 initiators. The primary safety outcome was major adverse cardiovascular events (MACE), a composite of hospitalization for acute myocardial infarction, stroke, or in-hospital cardiovascular death. We report the validation process for MACE endpoints in United Kingdom (UK) data sources: Clinical Practice Research Datalink (CPRD GOLD), The Health Improvement Network (THIN), and the Information Services Division (ISD) Scotland.

METHODS

Modified electronic algorithms from prior research identified potential MACE cases. Validation followed a common protocol, adapted for each database, with all information anonymized: (1) direct confirmation via linkage to hospital records (CPRD GOLD); (2) requests for additional clinical information through questionnaires (CPRD GOLD), free-text (THIN), or abstraction of hospital records (ISD); (3) manual review of electronic records of potential events retrieved by the algorithm (CPRD GOLD/THIN); and (4) event adjudication by three clinicians, blinded to exposure, for all remaining events.

RESULTS

Electronic algorithms identified 260 potential MACE cases: 38 confirmed via linkage to hospital records (CPRD GOLD), 56 ruled out as non-cardiovascular death cases (THIN), and three unavailable for review (ISD), leaving 163 potential cases. After manual review with additional information (steps 2 and 3), 45 were considered noncases (CPRD GOLD/THIN). Upon final adjudication (step 4), remaining potential events were adjudicated as definite (n = 62), probable (n = 10), possible (n = 13), or noncases (n = 33).

CONCLUSIONS

Given the limitations of relying solely on computer algorithms to identify cardiovascular outcomes, validation with clinical review is essential to guide interpretation.

Developing a Standardized and Reusable Method to Link Distributed Health Plan Databases to the National Death Index: Methods Development Study Protocol

BACKGROUND

Certain medications may increase the risk of death or death from specific causes (eg, sudden cardiac death), but these risks may not be identified in premarket randomized trials. Having the capacity to examine death in postmarket safety surveillance activities is important to the US Food and Drug Administration's (FDA) mission to protect public health. Distributed networks of electronic health plan databases used by the FDA to conduct multicenter research or medical product safety surveillance studies often do not systematically include death or cause-of-death information.

OBJECTIVE

This study aims to develop reusable, generalizable methods for linking multiple health plan databases with the Centers for Disease Control and Prevention's National Death Index Plus (NDI+) data.

METHODS

We will develop efficient administrative workflows to facilitate multicenter institutional review board (IRB) review and approval within a distributed network of 6 health plans. The study will create a distributed NDI+ linkage process that avoids sharing of identifiable patient information between health plans or with a central coordinating center. We will develop standardized criteria for selecting and retaining NDI+ matches and methods for harmonizing linked information across multiple health plans. We will test our processes within a use case comprising users and nonusers of antiarrhythmic medications.

RESULTS

We will use the linked health plan and NDI+ data sets to estimate the incidences and incidence rates of mortality and specific causes of death within the study use case and compare the results with reported estimates. These comparisons provide an opportunity to assess the performance of the developed NDI+ linkage approach and lessons for future studies requiring NDI+ linkage in distributed database settings. This study is approved by the IRB at Harvard Pilgrim Health Care in Boston, MA. Results will be presented to the FDA at academic conferences and published in peer-reviewed journals.

CONCLUSIONS

This study will develop and test a reusable distributed NDI+ linkage approach with the goal of providing tested NDI+ linkage methods for use in future studies within distributed data networks. Having standardized and reusable methods for systematically obtaining death and cause-of-death information from NDI+ would enhance the FDA's ability to assess mortality-related safety questions in the postmarket, real-world setting.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/21811.

In-Hospital Cardiopulmonary Resuscitation of Patients With Human Immunodeficiency Virus Infection: A Population-Based Cohort Study of Epidemiology and Outcomes

Background

Marked improvements were realized in both short-term and long-term outcomes of human immunodeficiency virus (HIV)-infected patients following the introduction of combination antiretroviral therapy. However, the contemporary population-level patterns of in-hospital cardiopulmonary resuscitation (CPR) and the outcomes of HIV-infected patients were not systematically examined.

Methods

We used the Texas Inpatient Public Use Data File to identify hospitalizations aged ≥ 18 years with and without HIV during 2009 - 2014, and those in each group who have undergone in-hospital CPR. Short-term survival (defined as absence of hospital mortality or discharge to hospice) following in-hospital CPR was examined. Multivariate logistic regression modeling was used to assess the prognostic impact of HIV infection following in-hospital CPR and predictors of short-term survival among HIV hospitalizations.

Results

In-hospital CPR was reported in 437 and 54,135 hospitalizations with and without HIV, respectively. The rates of in-hospital CPR (per 1,000 hospitalizations) were 4.4 and 4.1 among hospitalizations with and without HIV, respectively (P = 0.1659). The corresponding rates of in-hospital CPR among decedents were 11% and 11.8%, respectively (P = 0.1531). Crude short-term survival following in-hospital CPR among hospitalizations with and without HIV was 19% and 26.8%, respectively (P = 0.0003). The corresponding adjusted short-term survival between 2009 and 2014 rose from 14.2% to 27% (P = 0.0009 for trend) and from 25.5% to 28% (P < 0.0001 for trend). HIV infection was associated with lower odds of short-term survival following in-hospital CPR (adjusted odds ratio (aOR): 0.50, 95% confidence interval (95% CI): 0.39 - 0.65). Select comorbid conditions (congestive heart failure, aOR: 2.03, 95% CI: 1.20 - 2.46; cerebrovascular disease, aOR: 2.08, 95% CI: 1.15 - 3.75; and diabetes, aOR: 1.53, 95% CI 1.31 - 4.71) were the only independent predictors of short-term survival following in-hospital CPR among HIV hospitalizations.

Conclusions

The rates of in-hospital CPR were similar among hospitalizations with and without HIV infection, with similar level of selectivity among decedents. Although HIV infection was associated with lower short-term survival following in-hospital CPR for the whole cohort, a dramatic improvement was observed during the study period among affected patients, with short-term survival rates becoming near-similar to those without HIV. Further studies are needed to identify modifiable factors to further improve the outcomes following in-hospital CPR among patients with HIV infection.

Diagnostic Algorithms for Cardiovascular Death in Administrative Claims Databases: A Systematic Review

INTRODUCTION

Valid algorithms for identification of cardiovascular (CV) deaths allow researchers to reliably assess the CV safety of medications, which is of importance to regulatory science, patient safety, and public health.

OBJECTIVE

The aim was to conduct a systematic review of algorithms to identify CV death in administrative health plan claims databases.

METHODS

We searched MEDLINE, EMBASE, and Cochrane Library for English-language studies published between January 1, 2012 and October 17, 2017. We examined references in systematic reviews to identify earlier studies. Selection included any observational study using electronic health care data to evaluate the sensitivity, specificity, positive predictive value (PPV), or negative predictive value (NPV) of algorithms for CV death (sudden cardiac death [SCD], myocardial infarction [MI]-related death, or stroke-related death) among adults aged ≥ 18 years in the United States. Data were extracted by two independent reviewers, with disagreements resolved through further discussion and consensus. The Quality Assessment of Diagnostic Accuracy Studies-2 instrument was used to assess the risk of bias.

RESULTS

Five studies (n = 4 on SCD, n = 1 on MI- and stroke-related death) were included after a review of 2053 citations. All studies reported algorithm PPVs, with incomplete reporting on other accuracy parameters. One study was at low risk of bias, three studies were at moderate risk of bias, and one study was at unclear risk of bias. Two studies identified community-occurring SCD: one identified events using International Classification of Disease, Ninth Revision (ICD-9) codes on death certificates and other criteria from medical claims (PPV = 86.8%) and the other identified events resulting in hospital presentation using first-listed ICD-9 codes on emergency department or inpatient medical claims (PPV = 92.3%). Two studies used death certificates alone to identify SCD (PPV = 27% and 32%, respectively). One study used medical claims to identify CV death (PPV = 36.4%), coronary heart disease mortality (PPV = 28.3%), and stroke mortality (PPV = 34.5%).

CONCLUSION

Two existing algorithms based on medical claims diagnoses with or without death certificates can accurately identify SCD to support pharmacoepidemiologic studies. Developing valid algorithms identifying MI- and stroke-related death should be a research priority. PROSPERO 2017 CRD42017078745.

A comparison of two algorithms to identify sudden cardiac deaths in computerized databases

PURPOSE

Two previously validated algorithms to identify sudden cardiac death using administrative data showed high positive predictive value. We evaluated the agreement between the algorithms using data from a common source population.

METHODS

We conducted a cross-sectional study to assess the percent agreement between deaths identified by two sudden cardiac death algorithms using Tennessee Medicaid and death certificate data from 2007 through 2014. The source population included all deceased patients aged 18 to 64 years with Medicaid enrollment in the 6 months prior to death. To identify sudden cardiac deaths, algorithm 1 used only hospital/emergency department (ED) claims from encounters at the time of death, and algorithm 2 required death certificates and used claims data for specific exclusion criteria.

RESULTS

We identified 34 107 deaths in the source population over the study period. The two algorithms identified 4372 potential sudden cardiac deaths: Algorithm 1 identified 3117 (71.3%) and algorithm 2 identified 1715 (39.2%), with 460 (10.5%) deaths identified by both algorithms. Of the deaths identified by algorithm 1, 1943 (62.3%) had an underlying cause of death not specified in algorithm 2. Of the deaths identified by algorithm 2, 1053 (61.4%) had no record of a hospital or ED encounter at the time of death, and 202 (11.8%) had a discharge diagnosis code not specified in algorithm 1.

CONCLUSIONS

We found low agreement between the two algorithms for identification of sudden cardiac deaths because of differences in sudden cardiac death definitions and data sources.

In-hospital cardiopulmonary resuscitation of patients with cirrhosis: A population-based analysis

Objective

To examine the epidemiology and outcomes of in-hospital cardiopulmonary resuscitation (CPR) among patients with cirrhosis.

Methods

We used the Texas Inpatient Public Use Data File to identify hospitalizations aged ≥ 18 years with and without cirrhosis during 2009–2014 and those in each group who have undergone in-hospital CPR. Short-term survival (defined as absence of hospital mortality or discharge to hospice) following in-hospital CPR was examined. Multivariate logistic regression modeling was used to assess the prognostic impact of cirrhosis following in-hospital CPR and predictors of short-term survival among cirrhosis hospitalizations.

Results

In-hospital CPR was reported in 2,511 and 51,969 hospitalizations with and without cirrhosis, respectively. The rate of in-hospital CPR (per 1,000 hospitalizations) was 7.6 and 4.0 among hospitalizations with and without cirrhosis, respectively. The corresponding rate of in-hospital CPR among decedents was 10.7% and 13.4%, respectively. Short-term survival following in-hospital CPR among hospitalizations with and without cirrhosis was 14.9% and 27.3%, respectively, and remained unchanged over time on adjusted analyses among the former (p = 0.1753), while increasing among the latter (p = 0.0404). Cirrhosis was associated with lower odds of short-term survival following in-hospital CPR (adjusted odds ratio [aOR] 0.55 [95% CI: 0.49–0.62]). Lack of health insurance (vs. Medicare) (aOR] 0.47 [95% CI: 0.34–0.67]) and sepsis ([aOR] 0.67 [95% CI: 0.53–85]) were associated with lower odds of short-term survival following in-hospital CPR among cirrhosis hospitalizations.

Conclusions

The rate of in-hospital CPR was nearly 2-fold higher among hospitalizations with cirrhosis than among those without it, though it was used more selectively among the former. Short-term survival following in-hospital CPR remained markedly lower among cirrhosis hospitalizations, while progressively improving among those without cirrhosis. Strategies to increase access to health insurance and improve early identification and control of infection should be explored in future preventive and interventional efforts.

Macrolides, Digoxin Toxicity and the Risk of Sudden Death: A Population-Based Study

INTRODUCTION

Digoxin is commonly prescribed to elderly patients with heart failure and atrial fibrillation, and macrolide antibiotics markedly increase the risk of digoxin toxicity.

OBJECTIVE

The aim was to determine whether, in older patients receiving digoxin, macrolide antibiotics are associated with sudden death.

METHODS

We used a population-based, nested, case-control design from January 1, 1994 to December 31, 2012 in a cohort of Ontario residents aged 66 years or older prescribed digoxin. The primary outcome was the risk of sudden death within 14 days of exposure to one of three antibiotics (erythromycin, clarithromycin, or azithromycin), relative to cefuroxime.

RESULTS

Among 39,072 Ontarians who died suddenly while receiving digoxin, 586 died within 14 days of receiving a study antibiotic. Relative to cefuroxime, we found no statistically significant increase in the risk of sudden death following treatment with erythromycin [adjusted odds ratio (aOR) 0.98; 95% confidence interval (CI) 0.65-1.48], clarithromycin (aOR 1.25; 95% CI 0.94-1.65), or azithromycin (aOR 1.07; 95% CI 0.75-1.53).

CONCLUSION

This finding reinforces the cardiovascular safety of macrolide antibiotics in a high-risk population.

Algorithms used to identify ventricular arrhythmias and sudden cardiac death in retrospective studies: a systematic literature review

Drug-induced QT interval prolongation may increase the risk of sudden cardiac death or ventricular arrhythmias (SCD/VA), and therefore affects the safety profile of medications. Administrative databases can be used to inform pharmacoepidemiologic drug safety studies for such rare events. In order to compare event rates between studies, validated operational definitions of these events are needed. We conducted a systematic literature review in PubMed to identify algorithms for SCD/VA. Twenty-two studies were included in the review. Fifteen (68%) studies evaluated International Classification of Diseases, 9th revision (ICD-9) based medical data, of which six utilized a common, validated operational definition. This algorithm was based on principal hospitalization discharge diagnosis or first-listed emergency department visit diagnosis, with an average positive predictive value (PPV) of 85%. Four studies evaluated ICD-9 based death data, of which three utilized a common algorithm with an average PPV of 88%. Further validation of ICD, 10th revision algorithms are needed. In conclusion, we identified a validated algorithm for SCD/VA in medical data, as well as in death data. As such, to ensure comparability between new research and the existing literature, pharmacoepidemiologic research in this area should utilize common, validated algorithms, such as the ones identified in our review, to operationally define these events.

Comparative Safety of Sulfonylurea and Metformin Monotherapy on the Risk of Heart Failure: A Cohort Study

BACKGROUND

Medications that impact insulin sensitivity or cause weight gain may increase heart failure risk. Our aim was to compare heart failure and cardiovascular death outcomes among patients initiating sulfonylureas for diabetes mellitus treatment versus metformin.

METHODS AND RESULTS

National Veterans Health Administration databases were linked to Medicare, Medicaid, and National Death Index data. Veterans aged ≥18 years who initiated metformin or sulfonylureas between 2001 and 2011 and whose creatinine was <1.4 (females) or 1.5 mg/dL (males) were included. Each metformin patient was propensity score-matched to a sulfonylurea initiator. The outcome was hospitalization for acute decompensated heart failure as the primary reason for admission or a cardiovascular death. There were 126 867 and 79 192 new users of metformin and sulfonylurea, respectively. Propensity score matching yielded 65 986 per group. Median age was 66 years, and 97% of patients were male; hemoglobin A1c 6.9% (6.3, 7.7); body mass index 30.7 kg/m2 (27.4, 34.6); and 6% had heart failure history. There were 1236 events (1184 heart failure hospitalizations and 52 cardiovascular deaths) among sulfonylurea initiators and 1078 events (1043 heart failure hospitalizations and 35 cardiovascular deaths) among metformin initiators. There were 12.4 versus 8.9 events per 1000 person-years of use (adjusted hazard ratio 1.32, 95%CI 1.21, 1.43). The rate difference was 4 heart failure hospitalizations or cardiovascular deaths per 1000 users of sulfonylureas versus metformin annually.

CONCLUSIONS

Predominantly male patients initiating treatment for diabetes mellitus with sulfonylurea had a higher risk of heart failure and cardiovascular death compared to similar patients initiating metformin.

High-Dose Citalopram and Escitalopram and the Risk of Out-of-Hospital Death

OBJECTIVE

Studies demonstrating that higher doses of citalopram (> 40 mg) and escitalopram (> 20 mg) prolong the corrected QT interval prompted regulatory agency warnings, which are controversial, given the absence of confirmatory clinical outcome studies. We compared the risk of potential arrhythmia-related deaths for high doses of these selective serotonin reuptake inhibitors (SSRIs) to that for equivalent doses of fluoxetine, paroxetine, and sertraline.

METHODS

The Tennessee Medicaid retrospective cohort study included 54,220 persons 30-74 years of age without cancer or other life-threatening illness who were prescribed high-dose SSRIs from 1998 through 2011. The mean age was 47 years, and 76% were female. Demographic characteristics and comorbidity for individual SSRIs were comparable. Because arrhythmia-related deaths are typically sudden and occur outside the hospital, we analyzed out-of-hospital sudden unexpected death as well as sudden cardiac deaths, a more specific indicator of proarrhythmic effects.

RESULTS

The adjusted risk of sudden unexpected death for citalopram did not differ significantly from that for the other SSRIs. The respective hazard ratios (HRs) for citalopram versus escitalopram, fluoxetine, paroxetine, and sertraline were 0.84 (95% CI, 0.40-1.75), 1.24 (95% CI, 0.75-2.05), 0.75 (95% CI, 0.45-1.24), and 1.53 (95% CI, 0.91-2.55). There were no significant differences for sudden cardiac death or all study deaths, nor were there significant differences among high-risk patients (≥ 60 years of age, upper quartile baseline cardiovascular risk). Escitalopram users had no significantly increased risk for any study end point.

CONCLUSIONS

We found no evidence that risk of sudden unexpected death, sudden cardiac death, or total mortality for high-dose citalopram and escitalopram differed significantly from that for comparable doses of fluoxetine, paroxetine, and sertraline.

Improving the Identification of Out-of-Hospital Sudden Cardiac Deaths in a General Practice Research Database

Background

The ascertainment of sudden cardiac death (SCD) in electronic health databases is challenging.

Objectives

Our objective was to evaluate the applicability of the validated computer definition of SCD developed by Chung et al. in a retrospective study of SCD and domperidone exposure in the Clinical Practice Research Datalink (CPRD).

Methods

We assessed out-of-hospital SCD by applying the validated computer definition and linking data with Hospital Episode Statistics and death certificates. We developed a separate algorithm to identify end-of-life care in noninstitutionalized patients and excluded associated deaths from the analysis to address their misclassification as SCD.

Results

Of the 681,104 patients in the study cohort, 3444 were initially classified as out-of-hospital SCD. Next, 163 deaths were identified as expected deaths by our algorithm for end-of-life home care. After review of patient profiles, 162 were classified as expected deaths because of evidence that the patient received palliative or end-of-life care, but one was a false negative. The exclusion of such cases appreciably changed the odds ratio for current exposure to domperidone compared with non-use of study medications from 2.09 (95 % confidence interval [CI] 1.16–3.74) to 1.71 (95 % CI 0.92–3.18). A similar effect on the odds ratio was observed for current exposure to metoclopramide but not to proton pump inhibitors.

Conclusions

Our algorithm to identify end-of-life care at home in the CPRD performed well, with only one false negative. The exclusion of misclassified cases of SCD reduced the magnitude of the odds ratios for SCD associated with domperidone and metoclopramide exposure by controlling protopathic bias.

Electronic supplementary material

The online version of this article (doi:10.1007/s40801-016-0086-1) contains supplementary material, which is available to authorized users.

Comparative Effectiveness of Insulin versus Combination Sulfonylurea and Insulin: a Cohort Study of Veterans with Type 2 Diabetes

BACKGROUND

Type 2 diabetes patients often initiate treatment with a sulfonylurea and subsequently intensify their therapy with insulin. However, information on optimal treatment regimens for these patients is limited.

OBJECTIVE

To compare risk of cardiovascular disease (CVD) and hypoglycemia between sulfonylurea initiators who switch to or add insulin.

DESIGN

This was a retrospective cohort assembled using national Veterans Health Administration (VHA), Medicare, and National Death Index databases.

PARTICIPANTS

Veterans who initiated diabetes treatment with a sulfonylurea between 2001 and 2008 and intensified their regimen with insulin were followed through 2011.

MAIN MEASURES

The association between insulin versus sulfonylurea + insulin and time to CVD or hypoglycemia were evaluated using Cox proportional hazard models in a 1:1 propensity score-matched cohort. CVD included hospitalization for acute myocardial infarction or stroke, or cardiovascular mortality. Hypoglycemia included hospitalizations or emergency visits for hypoglycemia, or outpatient blood glucose measurements <60 mg/dL. Subgroups included age < 65 and ≥ 65 years and estimated glomerular filtration rate ≥ 60 and < 60 ml/min.

KEY FINDINGS

There were 1646 and 3728 sulfonylurea monotherapy initiators who switched to insulin monotherapy or added insulin, respectively. The 1596 propensity score-matched patients in each group had similar baseline characteristics at insulin initiation. The rate of CVD per 1000 person-years among insulin versus sulfonylurea + insulin users were 49.3 and 56.0, respectively [hazard ratio (HR) 0.85, 95 % confidence interval (CI) 0.64, 1.12]. Rates of first and recurrent hypoglycemia events per 1000 person-years were 74.0 and 100.0 among insulin users compared to 78.9 and 116.8 among sulfonylurea plus insulin users, yielding HR (95 % CI) of 0.94 (0.76, 1.16) and 0.87 (0.69, 1.10), respectively. Subgroup analysis results were consistent with the main findings.

CONCLUSIONS

Compared to sulfonylurea users who added insulin, those who switched to insulin alone had numerically lower CVD and hypoglycemia events, but these differences in risk were not statistically significant.

Ventricular tachyarrhythmia and sudden cardiac death with domperidone use in Parkinson's disease

AIM

Domperidone is preferentially used over other antiemetic agents to treat digestive symptoms in Parkinson's disease (PD). Concerns have been raised regarding an increased risk of ventricular tachyarrhythmia and sudden cardiac death (VT/SCD) associated with domperidone in the general population. However, the risk in PD is unknown.

METHODS

We conducted a multicentre retrospective cohort study using administrative databases from seven Canadian provinces and the UK Clinical Practice Research Datalink. Using a nested case-control analysis, we estimated the rate ratios (RRs) of VT/SCD associated with domperidone use compared to no use in patients newly-diagnosed with PD. VT/SCD events were identified using administrative medical records and vital statistics with a manual review of all potential cases. Meta-analytic methods were used to estimate overall effects across sites.

RESULTS

Among 214 962 patients with PD, 2907 cases of VT/SCD were identified during 886 581 person-years of follow-up (incidence rate 3.28 per 1000 persons per year). Current use of domperidone was associated with a non-statistically significant 22% increased risk of VT/SCD (RR 1.22; 95% CI 0.99-1.50) compared with no use. The risk was significantly elevated in those with a history of cardiovascular disease (RR 1.38; 95% CI 1.07-1.78), but not in those without (RR 1.21; 95% CI 0.81-1.81). Dose and duration of use did not affect the magnitude of the risk.

CONCLUSION

Domperidone use may increase the risk of VT/SCD in patients with PD, particularly those with a history of cardiovascular disease. This risk may be underestimated because of imprecision in identifying VT/SCD events.

Risk of Out-of-Hospital Sudden Cardiac Death in Users of Domperidone, Proton Pump Inhibitors, or Metoclopramide: A Population-Based Nested Case-Control Study

INTRODUCTION

Epidemiological studies have linked domperidone use with serious cardiac arrhythmias, including sudden cardiac death, but data on age, dose, and duration of use are limited.

OBJECTIVES

The aim of this study was to assess the risk of out-of-hospital sudden cardiac death associated with domperidone use versus proton pump inhibitors (PPIs), metoclopramide, or non-use of all three medications, and to evaluate the risk of sudden cardiac death in relation to age and domperidone dose.

METHODS

This was a population-based case-control study nested in a cohort of subjects aged ≥2 years in the Clinical Practice Research Datalink with one or more prescriptions for domperidone, any PPI, or metoclopramide from 2005 to 2011. Out-of-hospital sudden cardiac death was assessed by linkage with Hospital Episode Statistics and death certificates. Controls were matched on age, sex, and medical practice. The risk of sudden cardiac death in domperidone users versus risk in users of PPIs or metoclopramide was evaluated with multivariable conditional logistic regression; case-crossover analysis addressed possible residual confounding.

RESULTS

From the study cohort (n = 681,104), 3239 sudden cardiac death cases were matched to 12,572 controls. The adjusted odds ratio (95 % confidence interval) for sudden cardiac death with current use of domperidone alone was 1.71 (0.92-3.18) versus non-use of study medications, 1.26 (0.68-2.34) versus current PPI use, and 0.40 (0.17-0.94) current metoclopramide use. The adjusted odds ratio (95 % confidence interval) relative to exposure to no study drug for domperidone >30 mg/day (eight cases, five controls) was 3.20 (0.59-17.3) and 1.65 (0.89-3.07) for age ≥61 years (27 cases, 49 controls). The odds ratio (95 % confidence interval) was 3.17 (1.72-5.83) for within-person periods of domperidone use versus non-use in the case-crossover analysis.

CONCLUSIONS

Compared with non-use of any study drug, current domperidone use was associated with sudden cardiac death in nested case-control and case-crossover analyses, with a suggestion of higher risk in older persons and users of higher daily doses.

Real world effectiveness of primary implantable cardioverter defibrillators implanted during hospital admissions for exacerbation of heart failure or other acute co-morbidities: cohort study of older patients with heart failure

OBJECTIVES

To examine the effectiveness of primary implantable cardioverter defibrillators (ICDs) in elderly patients receiving the device during a hospital admission for exacerbation of heart failure or other acute co-morbidities, with an emphasis on adjustment for early mortality and other factors reflecting healthy candidate bias rather than the effect of the ICD.

DESIGN

Retrospective cohort study.

SETTING

Linked data from the Centers for Medicare and Medicaid Services and American College of Cardiology-National Cardiovascular Data Registry ICD registry, nationwide heart failure registry, and Medicare claims data 2004-09.

POPULATION

23,111 patients aged ≥ 66 who were admitted to hospital for exacerbation of heart failure or other acute co-morbidities and eligible for primary ICDs.

MAIN OUTCOME MEASURES

All cause mortality and sudden cardiac death. Latency analyses with Cox regression were used to derive crude hazard ratios and hazard ratios adjusted for high dimension propensity score for outcomes after 180 days from index implantation or discharge.

RESULTS

Patients who received an ICD during a hospital admission had lower crude mortality risk than patients who did not receive an ICD (40% v 60% at three years); however, with conditioning on 180 day survival and with adjustment for high dimension propensity score, the apparent benefit with ICD was no longer evident for sudden cardiac death (adjusted hazard ratio 0.95, 95% confidence interval 0.78 to 1.17) and had a diminished impact on total mortality (0.91, 0.82 to 1.00). There were trends towards a benefit with ICD in reducing mortality or sudden cardiac death in patients who had had a myocardial infarction more than 40 days previously, left bundle branch block, or low serum B type natriuretic peptide; however, these trends did not reach significance.

CONCLUSION

After adjustment for healthy candidate bias and confounding, the benefits of primary ICD therapy seen in pivotal trials were not apparent in patients aged 66 or over who received ICDs during a hospital admission for exacerbation of heart failure or other acute co-morbidities. Future research is warranted to further identify subgroups of elderly patients who are more likely to benefit from ICDs. Recognition of those patients whose dominant risk factors are from decompensated heart failure and non-cardiac co-morbidities will allow better focus on ICDs in those patients for whom the device offers the most benefit and provides meaningful prolonging of life.

Out-of-hospital mortality among patients receiving methadone for noncancer pain

IMPORTANCE

Growing methadone use in pain management has raised concerns regarding its safety relative to other long-acting opioids. Methadone hydrochloride may increase the risk for lethal respiratory depression related to accidental overdose and life-threatening ventricular arrhythmias.

OBJECTIVE

To compare the risk of out-of-hospital death in patients receiving methadone for noncancer pain with that in comparable patients receiving sustained-release (SR) morphine sulfate.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted using Tennessee Medicaid records from 1997 through 2009. The cohort included patients receiving morphine SR or methadone who were aged 30 to 74 years, did not have cancer or another life-threatening illness, and were not in a hospital or nursing home. At cohort entry, 32 742 and 6014 patients had filled a prescription for morphine SR or methadone, respectively. The patients' median age was 48 years, 57.9% were female, and comparable proportions had received cardiovascular, psychotropic, and other musculoskeletal medications. Nearly 90% of the patients received the opioid for back pain or other musculoskeletal pain. The median doses prescribed for morphine SR and methadone were 90 mg/d and 40 mg/d, respectively.

MAIN OUTCOMES AND MEASURES

The primary study end point was out-of-hospital mortality, given that opioid-related deaths typically occur outside the hospital.

RESULTS

There were 477 deaths during 28 699 person-years of follow-up (ie, 166 deaths per 10 000 person-years). After control for study covariates, patients receiving methadone had a 46% increased risk of death during the follow-up period, with an adjusted hazard ratio (HR) of 1.46 (95% CI, 1.17-1.83; P < .001), resulting in 72 (95% CI, 27-130) excess deaths per 10 000 person-years of follow-up. Methadone doses of 20 mg/d or less, the lowest dose quartile, were associated with an increased risk of death (HR, 1.59; 95% CI, 1.01-2.51, P = .046) relative to a comparable dose of morphine SR (<60 mg/d).

CONCLUSIONS AND RELEVANCE

The increased risk of death observed for patients receiving methadone in this retrospective cohort study, even for low doses, supports recommendations that it should not be a drug of first choice for noncancer pain.

Trimethoprim-sulfamethoxazole and risk of sudden death among patients taking spironolactone

BACKGROUND

Trimethoprim-sulfamethoxazole increases the risk of hyperkalemia when used with spironolactone. We examined whether this drug combination is associated with an increased risk of sudden death, a consequence of severe hyperkalemia.

METHODS

We conducted a population-based nested case-control study involving Ontario residents aged 66 years or older who received spironolactone between Apr. 1, 1994, and Dec. 31, 2011. Within this group, we identified cases as patients who died of sudden death within 14 days after receiving a prescription for trimethoprim-sulfamethoxazole or one of the other study antibiotics (amoxicillin, ciprofloxacin, norfloxacin or nitrofurantoin). For each case, we identified up to 4 controls matched by age and sex. We determined the odds ratio (OR) for the association between sudden death and exposure to each antibiotic relative to amoxicillin, adjusted for predictors of sudden death using a disease risk index.

RESULTS

Of the 11,968 patients who died of sudden death while receiving spironolactone, we identified 328 whose death occurred within 14 days after antibiotic exposure. Compared with amoxicillin, trimethoprim-sulfamethoxazole was associated with a more than twofold increase in the risk of sudden death (adjusted OR 2.46, 95% confidence interval [CI] 1.55-3.90). Ciprofloxacin (adjusted OR 1.55, 95% CI 1.02-2.38) and nitrofurantoin (adjusted OR 1.70, 95% CI 1.03-2.79) were also associated with an increased risk of sudden death, although the risk with nitrofurantoin was not apparent in a sensitivity analysis.

INTERPRETATION

The antibiotic trimethoprim-sulfamethoxazole was associated with an increased risk of sudden death among older patients taking spironolactone. When clinically appropriate, alternative antibiotics should be considered in these patients.

Co-trimoxazole and sudden death in patients receiving inhibitors of renin-angiotensin system: population based study

OBJECTIVE

To determine whether the prescription of co-trimoxazole with an angiotensin converting enzyme inhibitor or angiotensin receptor blocker is associated with sudden death.

DESIGN

Population based nested case-control study.

SETTING

Ontario, Canada, from 1 April 1994 to 1 January 2012.

PARTICIPANTS

Ontario residents aged 66 years or older treated with an angiotensin converting enzyme inhibitor or angiotensin receptor blocker. Cases were those who died suddenly shortly after receiving an outpatient prescription for one of co-trimoxazole, amoxicillin, ciprofloxacin, norfloxacin, or nitrofurantoin. Each case was matched with up to four controls on age, sex, chronic kidney disease, and diabetes.

MAIN OUTCOME MEASURE

Odds ratio for the association between sudden death and exposure to each antibiotic relative to amoxicillin, after adjustment for predictors of sudden death according to a disease risk index.

RESULTS

Of 39,879 sudden deaths, 1027 occurred within seven days of exposure to an antibiotic and were matched to 3733 controls. Relative to amoxicillin, co-trimoxazole was associated with an increased risk of sudden death (adjusted odds ratio 1.38, 95% confidence interval 1.09 to 1.76). The risk was marginally higher at 14 days (adjusted odds ratio 1.54, 1.29 to 1.84). This corresponds to approximately three sudden deaths within 14 days per 1000 co-trimoxazole prescriptions. Ciprofloxacin (a known cause of QT interval prolongation) was also associated with an increased risk of sudden death (adjusted odds ratio 1.29, 1.03 to 1.62), but no such risk was observed with nitrofurantoin or norfloxacin.

CONCLUSIONS

In older patients receiving angiotensin converting enzyme inhibitors or angiotensin receptor blockers, co-trimoxazole is associated with an increased risk of sudden death. Unrecognized severe hyperkalemia may underlie this finding. When appropriate, alternative antibiotics should be considered in such patients.

Cardiac mortality in users of olmesartan, other angiotensin-receptor blockers and angiotensin-converting enzyme inhibitors

PURPOSE

Clinical trials of olmesartan for prevention of progression of renal disease in patients with diabetes showed renal protection but an unexpected imbalance in cardiac deaths. The US Food and Drug Administration requested from the manufacturer a cohort study of olmesartan, other angiotensin-receptor blockers (ARBs), and angiotensin-converting enzyme (ACE) inhibitors in a large population.

METHODS

A retrospective cohort study was conducted with the cooperation of a US health insurer. Subject entry and follow-up ran from 2002 through 2009. In propensity-matched cohorts, the primary analysis considered continuous current users. Endpoints were sudden cardiac death (SCD) and all-cause mortality, identified through the US National Death Index, supplemented by insurance and hospital discharge data. Statistical estimation was based on proportional hazards analyses with 95% confidence intervals. Power calculations had shown that 25,000 olmesartan initiators would be required to detect relative risks (RRs) of SCD of twofold or greater.

RESULTS

A total of 57,123 initiators of olmesartan were matched 1:2 to initiators of other ARBs and 41,801 to initiators of ACE inhibitors. Average follow-up time ranged from 8 to 9 months. Olmesartan initiators and comparators experienced similar patterns of both outcomes, with RRs ≤1.0 and upper confidence bounds ≤1.6. Among persons with prior use of hypoglycemic agents, in comparison with other ARBs, the RR of SCD for olmesartan users was 0.8, with an upper confidence bound of 2.2.

CONCLUSION

The results of this well-powered study do not raise concerns for the risk of SCD or death from all causes among olmesartan users in comparison with users of other ARBs or ACE inhibitors.

Cardiovascular and mortality risk in elderly Medicare beneficiaries treated with olmesartan versus other angiotensin receptor blockers

PURPOSE

In the randomized trial, Randomized Olmesartan and Diabetes Microalbuminuria Prevention, acute cardiovascular death was increased nearly fivefold in diabetic patients treated with high-dose olmesartan, an angiotensin receptor blocker (ARB), compared with placebo.

METHODS

Medicare beneficiaries were entered into new-user cohorts of olmesartan or other ARBs and followed on therapy for occurrence of acute myocardial infarction, stroke, or death. Analyses focused on specific subgroups defined by diabetes status, ARB dose, and duration of therapy. Hazard ratios (HR) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression, with other ARBs as reference.

RESULTS

A total of 158,054 olmesartan and 724,673 other ARB users were followed for 54,285 and 260,390 person-years, respectively, during which 9237 endpoint events occurred. Lower-dose olmesartan was not associated with increased risk for any endpoint, regardless of duration of use. High-dose olmesartan for 6 months or longer was associated with increased risk of death in patients with diabetes (HR 2.03, 95%CI 1.09-3.75, p = 0.02) and with reduced risk in nondiabetic patients (HR 0.46, 95%CI 0.24-0.86, p = 0.01). Some, but not all, sensitivity analyses suggested that selective prescribing of olmesartan to healthier patients (channeling bias) may have accounted for the reduced risk in nondiabetic patients.

CONCLUSIONS

High-dose olmesartan was associated with an increased risk of death in diabetic patients treated for 6 months or longer and with a reduced risk of death in nondiabetic patients, when compared with use of other ARBs. This latter effect was probably because of selective prescribing of olmesartan to healthier patients, although effect modification cannot be excluded. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Cardiovascular risk in rheumatoid arthritis: comparing TNF-α blockade with nonbiologic DMARDs

BACKGROUND

Elevated tumor necrosis factor (TNF)-α likely contributes to the excess cardiovascular risk observed in rheumatoid arthritis. We compared the cardiovascular risk in rheumatoid arthritis patients starting a TNF-α blocking agent versus a nonbiologic disease-modifying antirheumatic drug (nbDMARD).

METHODS

Subjects with rheumatoid arthritis participating in several different US insurance programs between 1998 and 2007 who received methotrexate were eligible. Those who added a TNF-α blocking agent were compared with subjects who added a nbDMARD in Cox regression models stratified by propensity score decile and adjusted for oral glucocorticoid dosage. We examined the composite cardiovascular end point of myocardial infarction, stroke, or coronary re-vascularization after 6 months.

RESULTS

We compared 8656 new users of a nbDMARD with 11,587 new users of a TNF-α blocking agent with similar baseline covariates. Incidence rates per 100 person-years for the composite cardiovascular end point were 3.05 (95% confidence interval [CI], 2.54-3.65) for nbDMARDs and 2.52 (95% CI, 2.12-2.98) for TNF-α blocking agents. The hazard ratio (HR) for the TNF-α blocking agent compared with nbDMARD carrying the first exposure forward was 0.80 (95%, CI 0.62-1.04), while the HR for the as-treated analysis was 0.71 (95% CI, 0.52-0.97). The potential cardiovascular benefit of TNF-α blocking agents was strongest among individuals ≥65 years of age (HR 0.52; 95% CI, 0.34 -0.77; P for interaction = 0.075).

CONCLUSION

Among subjects with rheumatoid arthritis, TNF-α blocking agents may be associated with a reduced risk of cardiovascular events compared with an nbDMARD. Randomized controlled clinical trials should be considered to test this hypothesis.

Propoxyphene and the risk of out-of-hospital death

PURPOSE

The opioid analgesic propoxyphene was withdrawn from the US market in 2010, motivated by concerns regarding fatality in overdose and adverse cardiac effects, including prolongation of the QT interval. These concerns were based on case reports, summary vital statistics, and surrogate endpoint studies.

METHODS

Using the linked Tennessee Medicaid database (1992-2007), we conducted a retrospective cohort study that compared risk of sudden cardiac, medication toxicity, and total out-of-hospital death for propoxyphene users with that for comparable nonusers of any prescribed opioid analgesic and users of hydrocodone, an opioid with similar indications. Cohort members had 1,873,500 propoxyphene prescriptions, 1,873,500 matched nonuser control periods, and 936,750 matched hydrocodone prescriptions.

RESULTS

Current propoxyphene users had no increased risk for sudden cardiac death (versus nonusers: hazard ratio [HR] = 1.00 [0.81-1.23]; versus current hydrocodone users: HR = 0.91 [0.68-1.21]) but did have increased risk for medication toxicity deaths (versus nonusers: HR = 1.85 [1.07-3.19], p = 0.027; versus current hydrocodone users: HR = 2.10 [0.87-5.10], p = 0.100). Because toxicity deaths were a small proportion of study deaths, total out-of-hospital mortality differed by less than 10% between the study groups and was not significantly elevated for propoxyphene (versus nonusers: HR = 1.09 [0.95-1.25]; versus current hydrocodone users: HR = 1.06 [0.87-1.29] ).

CONCLUSIONS

Our findings support the concern that propoxyphene has greater toxicity in overdose but do not provide evidence that it increases the risk of sudden cardiac death.

Improving sensitivity of machine learning methods for automated case identification from free-text electronic medical records

Background

Distinguishing cases from non-cases in free-text electronic medical records is an important initial step in observational epidemiological studies, but manual record validation is time-consuming and cumbersome. We compared different approaches to develop an automatic case identification system with high sensitivity to assist manual annotators.

Methods

We used four different machine-learning algorithms to build case identification systems for two data sets, one comprising hepatobiliary disease patients, the other acute renal failure patients. To improve the sensitivity of the systems, we varied the imbalance ratio between positive cases and negative cases using under- and over-sampling techniques, and applied cost-sensitive learning with various misclassification costs.

Results

For the hepatobiliary data set, we obtained a high sensitivity of 0.95 (on a par with manual annotators, as compared to 0.91 for a baseline classifier) with specificity 0.56. For the acute renal failure data set, sensitivity increased from 0.69 to 0.89, with specificity 0.59. Performance differences between the various machine-learning algorithms were not large. Classifiers performed best when trained on data sets with imbalance ratio below 10.

Conclusions

We were able to achieve high sensitivity with moderate specificity for automatic case identification on two data sets of electronic medical records. Such a high-sensitive case identification system can be used as a pre-filter to significantly reduce the burden of manual record validation.

Cardiovascular and mortality risks in Parkinson's disease patients treated with entacapone

The controlled trial Stalevo Reduction in Dyskinesia Evaluation in Parkinson's Disease (STRIDE-PD) reported an unexpected increase in acute myocardial infarction (AMI) with entacapone use in patients with Parkinson's disease (PD). The authors investigated whether entacapone increased cardiovascular and mortality risk compared with the use of a non-levodopa dopamine agonist (DA) or a selective monoamine oxidase type-B inhibitor (MAOBI). Using national Medicare data, a new-user cohort of elderly patients with PD treated with entacapone was propensity score (PS) matched with new users of either DA or MAOBI. The PS model included variables for sociodemographics, cardiovascular disease, medications, prior PD treatment, and comorbidities. Cox proportional hazards regression was used to compare on-therapy time to event for AMI, stroke, and death with DA-MAOBI as a reference. Study cohorts included 8681 entacapone-treated and 17,362 DA-MAOBI-treated initators who were followed for 2569 and 5385 person-years, respectively. Cohorts were closely balanced for all covariates. During follow-up, there were 106 AMIs, 89 strokes, and 201 deaths. The hazard ratio (HR) and 95% confidence interval (CI) associated with entacapone use was 0.86 (95% CI, 0.57-1.30) for AMI, 0.85 (95% CI, 0.54-1.35) for stroke, and 0.79 (95% CI, 0.58-1.07) for death. The risk was unchanged for treatment of ≤ 6 months' and>6 months' duration and was unaffected by adjustment for time-varying levodopa use during follow-up. The risk of each endpoint was not differentially affected by diabetes, ischemic heart disease, or kidney failure status. However, the risk of stroke was modified by the presence (HR, 2.09; 95% CI, 0.98-4.45) or absence (HR, 0.51; 95% CI, 0.27-0.95) of advanced PD-related morbidities (P value for interaction=0.004). Entacapone was not associated with an increased risk of AMI, stroke, or death in elderly patients with PD.

Azithromycin: more lethal than chloramphenicol?

Azithromycin is commonly used in sexual health and respiratory medicine, often when the diagnosis is presumptive. A recent article by Ray et al. reported that 1 out of 20 000 courses of low-dose azithromycin was associated with (sudden) cardiovascular death (including 1 out of 4000 courses in high-risk cardiovascular patients), ascribing these deaths to azithromycin itself. Here, we critique the actual study and examine conflicting data from randomised control trials, animal studies and observational data.

Validation of a computer case definition for sudden cardiac death in opioid users

BACKGROUND

To facilitate the use of automated databases for studies of sudden cardiac death, we previously developed a computerized case definition that had a positive predictive value between 86% and 88%. However, the definition has not been specifically validated for prescription opioid users, for whom out-of-hospital overdose deaths may be difficult to distinguish from sudden cardiac death.

FINDINGS

We assembled a cohort of persons 30-74 years of age prescribed propoxyphene or hydrocodone who had no life-threatening non-cardiovascular illness, diagnosed drug abuse, residence in a nursing home in the past year, or hospital stay within the past 30 days. Medical records were sought for a sample of 140 cohort deaths within 30 days of a prescription fill meeting the computer case definition. Of the 140 sampled deaths, 81 were adjudicated; 73 (90%) were sudden cardiac deaths. Two deaths had possible opioid overdose; after removing these two the positive predictive value was 88%.

CONCLUSIONS

These findings are consistent with our previous validation studies and suggest the computer case definition of sudden cardiac death is a useful tool for pharmacoepidemiologic studies of opioid analgesics.

Cardiovascular safety of central nervous system stimulants in children and adolescents: population based cohort study

OBJECTIVES

To evaluate the cardiac safety of central nervous system stimulants in children and adolescents.

DESIGN

Population based retrospective cohort study.

SETTING

Automated healthcare claims data from 1,219,847 children and young people eligible for 28 state Medicaid programmes from 1999 to 2006 linked to the Social Security Death Master File and the National Death Index.

PARTICIPANTS

Children and young people age 3-18 entered the cohort at the first diagnosis of a mental health condition commonly treated with stimulants (such as attention-deficit/hyperactivity disorder) after a minimum period of six months' eligibility and were followed until loss of eligibility, their 19th birthday, admission to hospital for longer than 30 days, or death. Exclusion criteria included transplant recipients, receipt of dialysis, or claims indicating substance misuse. We retained high risk groups with similar use of stimulants as low risk children (such as children with congenital heart disease). Sociodemographic characteristics, cardiac risk factors, and psychiatric diagnoses obtained from before the index period were summarised with a propensity score. We used discrete survival analysis to estimate the relative risk for periods of stimulant use and non-use, adjusted for propensity score and antipsychotic use for the full cohort and the high risk and low risk groups.

MAIN OUTCOME MEASURES

Composite endpoint of stroke, acute myocardial infarction, or sudden cardiac death; a secondary composite endpoint added ventricular arrhythmia

RESULTS

A total of 66 (95 including ventricular arrhythmia) events occurred during 2,321,311 years of follow-up. The odds ratio adjusted for propensity score and antipsychotic use for current versus no stimulant use was 0.62 (95% confidence interval 0.27 to 1.44), with a corresponding adjusted incidence rate of 2.2 and 3.5 per 100,000 patient years for current stimulant and non-use, respectively. Twenty six events occurred in high risk patients (incidence rate 63 per 100,000 patient years) with an odds ratio of 1.02 (0.28 to 3.69). Odds ratios for the secondary endpoint were similar to those for the primary endpoint (0.74, 0.38 to 1.46).

CONCLUSIONS

Treatment of children with central nervous stimulants is not significantly associated with an increase in the short term risk of severe cardiac events. Analyses cannot be generalised to children with long term use of stimulants. Furthermore, long term effects of slight increases in heart rate or blood pressure are unknown.

Azithromycin and the risk of cardiovascular death

BACKGROUND

Although several macrolide antibiotics are proarrhythmic and associated with an increased risk of sudden cardiac death, azithromycin is thought to have minimal cardiotoxicity. However, published reports of arrhythmias suggest that azithromycin may increase the risk of cardiovascular death.

METHODS

We studied a Tennessee Medicaid cohort designed to detect an increased risk of death related to short-term cardiac effects of medication, excluding patients with serious noncardiovascular illness and person-time during and shortly after hospitalization. The cohort included patients who took azithromycin (347,795 prescriptions), propensity-score-matched persons who took no antibiotics (1,391,180 control periods), and patients who took amoxicillin (1,348,672 prescriptions), ciprofloxacin (264,626 prescriptions), or levofloxacin (193,906 prescriptions).

RESULTS

During 5 days of therapy, patients taking azithromycin, as compared with those who took no antibiotics, had an increased risk of cardiovascular death (hazard ratio, 2.88; 95% confidence interval [CI], 1.79 to 4.63; P<0.001) and death from any cause (hazard ratio, 1.85; 95% CI, 1.25 to 2.75; P=0.002). Patients who took amoxicillin had no increase in the risk of death during this period. Relative to amoxicillin, azithromycin was associated with an increased risk of cardiovascular death (hazard ratio, 2.49; 95% CI, 1.38 to 4.50; P=0.002) and death from any cause (hazard ratio, 2.02; 95% CI, 1.24 to 3.30; P=0.005), with an estimated 47 additional cardiovascular deaths per 1 million courses; patients in the highest decile of risk for cardiovascular disease had an estimated 245 additional cardiovascular deaths per 1 million courses. The risk of cardiovascular death was significantly greater with azithromycin than with ciprofloxacin but did not differ significantly from that with levofloxacin.

CONCLUSIONS

During 5 days of azithromycin therapy, there was a small absolute increase in cardiovascular deaths, which was most pronounced among patients with a high baseline risk of cardiovascular disease. (Funded by the National Heart, Lung, and Blood Institute and the Agency for Healthcare Quality and Research Centers for Education and Research on Therapeutics.).

ADHD medications and risk of serious cardiovascular events in young and middle-aged adults

CONTEXT

More than 1.5 million US adults use stimulants and other medications labeled for treatment of attention-deficit/hyperactivity disorder (ADHD). These agents can increase heart rate and blood pressure, raising concerns about their cardiovascular safety.

OBJECTIVE

To examine whether current use of medications prescribed primarily to treat ADHD is associated with increased risk of serious cardiovascular events in young and middle-aged adults.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective, population-based cohort study using electronic health care records from 4 study sites (OptumInsight Epidemiology, Tennessee Medicaid, Kaiser Permanente California, and the HMO Research Network), starting in 1986 at 1 site and ending in 2005 at all sites, with additional covariate assessment using 2007 survey data. Participants were adults aged 25 through 64 years with dispensed prescriptions for methylphenidate, amphetamine, or atomoxetine at baseline. Each medication user (n = 150,359) was matched to 2 nonusers on study site, birth year, sex, and calendar year (443,198 total users and nonusers).

MAIN OUTCOME MEASURES

Serious cardiovascular events, including myocardial infarction (MI), sudden cardiac death (SCD), or stroke, with comparison between current or new users and remote users to account for potential healthy-user bias.

RESULTS

During 806,182 person-years of follow-up (median, 1.3 years per person), 1357 cases of MI, 296 cases of SCD, and 575 cases of stroke occurred. There were 107,322 person-years of current use (median, 0.33 years), with a crude incidence per 1000 person-years of 1.34 (95% CI, 1.14-1.57) for MI, 0.30 (95% CI, 0.20-0.42) for SCD, and 0.56 (95% CI, 0.43-0.72) for stroke. The multivariable-adjusted rate ratio (RR) of serious cardiovascular events for current use vs nonuse of ADHD medications was 0.83 (95% CI, 0.72-0.96). Among new users of ADHD medications, the adjusted RR was 0.77 (95% CI, 0.63-0.94). The adjusted RR for current use vs remote use was 1.03 (95% CI, 0.86-1.24); for new use vs remote use, the adjusted RR was 1.02 (95% CI, 0.82-1.28); the upper limit of 1.28 corresponds to an additional 0.19 events per 1000 person-years at ages 25-44 years and 0.77 events per 1000 person-years at ages 45-64 years.

CONCLUSIONS

Among young and middle-aged adults, current or new use of ADHD medications, compared with nonuse or remote use, was not associated with an increased risk of serious cardiovascular events. Apparent protective associations likely represent healthy-user bias.

ADHD drugs and serious cardiovascular events in children and young adults

BACKGROUND

Adverse-event reports from North America have raised concern that the use of drugs for attention deficit-hyperactivity disorder (ADHD) increases the risk of serious cardiovascular events.

METHODS

We conducted a retrospective cohort study with automated data from four health plans (Tennessee Medicaid, Washington State Medicaid, Kaiser Permanente California, and OptumInsight Epidemiology), with 1,200,438 children and young adults between the ages of 2 and 24 years and 2,579,104 person-years of follow-up, including 373,667 person-years of current use of ADHD drugs. We identified serious cardiovascular events (sudden cardiac death, acute myocardial infarction, and stroke) from health-plan data and vital records, with end points validated by medical-record review. We estimated the relative risk of end points among current users, as compared with nonusers, with hazard ratios from Cox regression models.

RESULTS

Cohort members had 81 serious cardiovascular events (3.1 per 100,000 person-years). Current users of ADHD drugs were not at increased risk for serious cardiovascular events (adjusted hazard ratio, 0.75; 95% confidence interval [CI], 0.31 to 1.85). Risk was not increased for any of the individual end points, or for current users as compared with former users (adjusted hazard ratio, 0.70; 95% CI, 0.29 to 1.72). Alternative analyses addressing several study assumptions also showed no significant association between the use of an ADHD drug and the risk of a study end point.

CONCLUSIONS

This large study showed no evidence that current use of an ADHD drug was associated with an increased risk of serious cardiovascular events, although the upper limit of the 95% confidence interval indicated that a doubling of the risk could not be ruled out. However, the absolute magnitude of such an increased risk would be low. (Funded by the Agency for Healthcare Research and Quality and the Food and Drug Administration.).

Methodological challenges in the coding and adjudication of sudden deaths in a large simple trial with observational follow-up: the ziprasidone observational study of cardiac outcomes (ZODIAC)

PURPOSE

The Ziprasidone Observational study of car DIAC Outcomes (ZODIAC), a large simple trial comparing ziprasidone versus olanzapine in real-world use, showed no difference in risk of sudden death. Upon the request of the US Food and Drug Administration, 205 fatal events were readjudicated applying ICD-10 coding rules for sudden death.

METHODS

A readjudication committee coded three domains (witness to death, time of symptom onset to death, and most likely cause of death) for use within algorithms consistent with ICD-10 rules. Relative risks (RR) and corresponding 95%CI were calculated for persons randomized to ziprasidone versus olanzapine, comparing 1-year incidence of sudden death, using multiple definitions.

RESULTS

Data on symptom onset to death and diagnosis of specific cardiac arrhythmias required by the ICD-10 rules were often lacking. Sensitivity analyses were conducted to explore the impact of cases suggestive of cardiac origin but missing data required by ICD-10 sudden death codes. Overall, the readjudicated data matched the study's initial findings, with no significant difference in 1-year mortality between ziprasidone and olanzapine for sudden death not otherwise specified and sudden cardiac death (R96.0 or R96.1 or I46.1; RR = 1.11, 95%CI 0.45- 2.77).

CONCLUSIONS

After outcome readjudication, ZODIAC found no difference in the risk of sudden death among those randomized to ziprasidone versus olanzapine. However, unlike hospital-based studies, fatal events in general population studies often occur outside hospital and often lack the clinical detail needed for the exact determination of symptom onset and event. Epidemiological evaluations of sudden death need to consider the limitations of the available data.