Seasonal and Geographic Variation in Adverse Event Reporting.

BACKGROUND: Many illnesses demonstrate seasonal and geographic variations. Pharmacovigilance is unique among public health surveillance systems in terms of the clinical diversity of the events under surveillance. Since many pharmacovigilance signal detection methodologies are geared towards looking for increased frequency of spontaneous adverse drug event (ADE) reporting over variable time frames, seasonality of ADEs may have implications for signal detection. OBJECTIVE: The aim of this study was to investigate whether a set of illnesses that might be expected to display seasonality in general, did so when spontaneously reported as ADEs. METHODS: We performed our analysis with the publically available US FDA Adverse Event Reporting System (FAERS) data. We selected a convenience sample of events possibly triggered by seasonal factors (hypothermia, Raynaud's phenomenon, photosensitivity reaction, heat exhaustion, heat stroke, and sunburn) and events for which previous literature experience suggests seasonality (anencephaly and interstitial lung disease). Our statistical procedures can be explained in terms of a simple physicogeometric setting: the unit circle divided into 6 (semiannual sinusoidal) or 12 (annual sinusoidal) arcs. When reporting frequencies (weights) are more or less evenly distributed across months, the center of mass of the circle would not be significantly displaced from the origin (0, 0). Distinct seasonal patterns will significantly displace the center of mass of the circle. RESULTS: Various patterns of seasonality were identified for some, but not all, events and region-event pairs. USA displayed the most instances of seasonality. Scandinavia did not display seasonality for any events. Seasonality was usually annual sinusoidal. Possible explanations for failure to observe seasonality are briefly considered. CONCLUSIONS: Understanding seasonality of spontaneous ADE reporting may have public health policy and research implications and may mitigate false-positive and missed true-positive pharmacovigilance signals. More systematic study of seasonality of spontaneous ADE reporting, including additional events with more or less biological rationale for seasonality, is a logical extension of this analysis.

Revisiting the reported signal of acute pancreatitis with rasburicase: an object lesson in pharmacovigilance.

INTRODUCTION: There is an interest in methodologies to expeditiously detect credible signals of drug-induced pancreatitis. An example is the reported signal of pancreatitis with rasburicase emerging from a study [the 'index publication' (IP)] combining quantitative signal detection findings from a spontaneous reporting system (SRS) and electronic health records (EHRs). The signal was reportedly supported by a clinical review with a case series manuscript in progress. The reported signal is noteworthy, being initially classified as a false-positive finding for the chosen reference standard, but reclassified as a 'clinically supported' signal. OBJECTIVE: This paper has dual objectives: to revisit the signal of rasburicase and acute pancreatitis and extend the original analysis via reexamination of its findings, in light of more contemporary data; and to motivate discussions on key issues in signal detection and evaluation, including recent findings from a major international pharmacovigilance research initiative. METHODOLOGY: We used the same methodology as the IP, including the same disproportionality analysis software/dataset for calculating observed to expected reporting frequencies (O/Es), Medical Dictionary for Regulatory Activities Preferred Term, and O/E metric/threshold combination defining a signal of disproportionate reporting. Baseline analysis results prompted supplementary analyses using alternative analytical choices. We performed a comprehensive literature search to identify additional published case reports of rasburicase and pancreatitis. RESULTS: We could not replicate positive findings (e.g. a signal or statistic of disproportionate reporting) from the SRS data using the same algorithm, software, dataset and vendor specified in the IP. The reporting association was statistically highlighted in default and supplemental analysis when more sensitive forms of disproportionality analysis were used. Two of three reports in the FAERS database were assessed as likely duplicate reports. We did not identify any additional reports in the FAERS corresponding to the three cases identified in the IP using EHRs. We did not identify additional published reports of pancreatitis associated with rasburicase. DISCUSSION: Our exercise stimulated interesting discussions of key points in signal detection and evaluation, including causality assessment, signal detection algorithm performance, pharmacovigilance terminology, duplicate reporting, mechanisms for communicating signals, the structure of the FAERs database, and recent results from a major international pharmacovigilance research initiative.

Safety of Perflutren Ultrasound Contrast Agents: A Disproportionality Analysis of the US FAERS Database.

INTRODUCTION: Perflutren microbubble/microsphere ultrasound contrast agents have a black-box warning based on case reports of serious cardiopulmonary events. There have been several subsequent observational safety studies. Large spontaneous reporting databases may help detect/refine signals of rare adverse events that elude other data sources/study designs. OBJECTIVE: The objective of this study was to supplement existing knowledge of the reported safety of perflutren using statistical analysis of spontaneous reports. METHODS: We analyzed information from the US Food and Drug Administration Adverse Event Reporting System using a disproportionality analysis. Analysis of overall reporting for perflutren was supplemented by subset (age, indication) analysis. A signal of disproportionate reporting (SDR) was defined as EB05 >2. RESULTS: Overall, 18/380 Preferred Terms and 1/83 Standardized Medical Queries had SDRs. Most were small (EB05 = 2-4). Back pain and flank pain were the largest SDRs followed by events compatible with signs/symptoms of hypersensitivity. The general pattern of SDRs in the subset analysis was consistent with the overall analysis. Almost all events with SDRs were literally or conceptually labeled. Except for chest pain (higher in the age <65 years subgroup) and back pain (higher in the age ≥65 years subgroup), there were no statistically significant differences between age subsets. Except for the Preferred Terms Pruritus and Urticaria and the narrow Standardized Medical Queries Ventricular tachyarrhythmia, Angioedema, Oropharyngeal allergic conditions, and Hypersensitivity (higher in the stress test subgroup), there were no statistically significant reporting differences between indication subsets. There were no SDRs associated with the major cardiovascular events of death, myocardial infarction/ischemia, angina, arrhythmias, or convulsions in any analysis. CONCLUSIONS: Our combined signal detection/evaluation analysis did not identify SDRs of novel adverse events or major cardiovascular events associated with perflutren ultrasound contrast agents. The negative results for major cardiovascular events extend previous signal evaluation exercises supporting the relative cardiovascular safety of these agents.

Pneumothorax as an adverse drug event: an exploratory aggregate analysis of the US FDA AERS database including a confounding by indication analysis inspired by Cornfield's condition.

INTRODUCTION: Pneumothorax is either primary or secondary. Secondary pneumothorax is usually due to trauma, including various non-pharmacologic iatrogenic triggers. Although not normally thought of as an adverse drug event (ADE) secondary pneumothorax is associated with numerous drugs, though it is often difficult to determine whether this association is causal in nature, or reflects an epiphenomenon of efficacy or inefficacy, or confounding by indication (CBI). Herein we explore this association in a large health authority drug safety surveillance database. METHODS: A quantitative pharmacovigilance (PhV) methodology known as disproportionality analysis was applied to the United States Food and Drug Administration (US FDA) Adverse Event Reporting System (AERS) database to explore the quantitative reporting dependencies between drugs and the adverse event pneumothorax as well the corresponding reporting dependencies between drugs and reported indications that may be risk factors for pneumothorax themselves in order to explore the potential contribution of CBI. RESULTS: We found 1. Multiple drugs are associated with pneumothorax; 2. Surfactants and oncology drugs account for most statistically distinctive associations with pneumothorax; 3. Pulmonary surfactants, pentamidine and nitric oxide have the largest statistical reporting associations 4. CBI may play a prominent role in reports of drug-associated pneumothorax. CONCLUSIONS: Disproportionality analysis (DA) can provide insights into the spontaneous reporting dependencies between drugs and pneumothorax. CBI assessment based on DA and Cornfield's inequality presents an additional novel option for the initial exploration of potential safety signals in PhV.

A quantitative analysis of the spontaneous reporting of congestive heart failure-related adverse events with systemic anti-fungal drugs.

To investigate spontaneous reporting relationships between representative antifungal agents and congestive heart failure (CHF)-related adverse events (AE) we performed multiple disproportionality analyses of the US FDA AERS database. Specifically we performed analysis of drug-AE associations (2D) plus drug-drug-AE and drug-AE-AE-associations (3D), the latter two to explore the potential contribution of reported pharmacodynamic interactions, overexposure from pharmacokinetic interactions, and drug overdose. Itraconazole displayed a pattern of statistical reporting dependencies across multiple analyses (2D and 3D). Amphotericin B was the only other antifungal that demonstrated a 2D SDR with CHF-related events. Itraconazole demonstrated multiple SDRs with calcium channel blockers in suspect drug-only 3D analysis. There was one other SDR with fluconazole and propanolol and three SDRs involving valproate and fluconazole that may have been do at least in part to duplicate reporting. Less specific 3D analysis including both suspect plus concomitant medications showed a greater number and variety of SDRs with multiple antifungals. Statistical reporting dependencies with CHF-related events did not appear to be a consistent pharmacological (e.g., azole/triazole)/therapeutic (i.e., antifungal) class effect. Itraconzole was unique in the pattern of statistical reporting dependencies with CHF-related events which is consistent with findings from independent data sets.