Sudden Sensorineural Hearing Loss after COVID-19 Vaccination: A Review of the Available Evidence through the Prism of Causality Assessment.

Sudden sensorineural hearing loss (SSNHL), a rare audiological condition that accounts for 1% of all cases of sensorineural hearing loss, can cause permanent hearing damage. Soon after the launch of global COVID-19 vaccination campaigns, the World Health Organization released a signal detection about SSNHL cases following administration of various COVID-19 vaccines. Post-marketing studies have been conducted in different countries using either pharmacovigilance or medico-administrative databases to investigate SSNHL as a potential adverse effect of COVID-19 vaccines. Here, we examine the advantages and limitations of each type of post-marketing study available. While pharmacoepidemiological studies highlight the potential association between drug exposure and the event, pharmacovigilance approaches enable causality assessment. The latter objective can only be achieved if an expert evaluation is provided using internationally validated diagnostic criteria. For a rare adverse event such as SSNHL, case information and quantification of hearing loss are mandatory for assessing seriousness, severity, delay onset, differential diagnoses, corrective treatment, recovery, as well as functional sequelae. Appropriate methodology should be adopted depending on whether the target objective is to assess a global or individual risk.

Safety Signal Generation for Sudden Sensorineural Hearing Loss Following Messenger RNA COVID-19 Vaccination: Postmarketing Surveillance Using the French Pharmacovigilance Spontaneous Reporting Database.

BACKGROUND: The World Health Organization recently described sudden sensorineural hearing loss (SSNHL) as a possible adverse effect of COVID-19 vaccines. Recent discordant pharmacoepidemiologic studies invite robust clinical investigations of SSNHL after COVID-19 messenger RNA (mRNA) vaccines. This postmarketing surveillance study, overseen by French public health authorities, is the first to clinically document postvaccination SSNHL and examine the role of potential risk factors. OBJECTIVE: This nationwide study aimed to assess the relationship between SSNHL and exposure to mRNA COVID-19 vaccines and estimate the reporting rate (Rr) of SSNHL after mRNA vaccination per 1 million doses (primary outcome). METHODS: We performed a retrospective review of all suspected cases of SSNHL after mRNA COVID-19 vaccination spontaneously reported in France between January 2021 and February 2022 based on a comprehensive medical evaluation, including the evaluation of patient medical history, side and range of hearing loss, and hearing recovery outcomes after a minimum period of 3 months. The quantification of hearing loss and assessment of hearing recovery outcomes were performed according to a grading system modified from the Siegel criteria. A cutoff of 21 days was used for the delay onset of SSNHL. The primary outcome was estimated using the total number of doses of each vaccine administered during the study period in France as the denominator. RESULTS: From 400 extracted cases for tozinameran and elasomeran, 345 (86.3%) spontaneous reports were selected. After reviewing complementary data, 49.6% (171/345) of documented cases of SSNHL were identified. Of these, 83% (142/171) of SSNHL cases occurred after tozinameran vaccination: Rr=1.45/1,000,000 injections; no difference for the rank of injections; complete recovery in 22.5% (32/142) of cases; median delay onset before day 21=4 days (median age 51, IQR 13-83 years); and no effects of sex. A total of 16.9% (29/171) of SSNHL cases occurred after elasomeran vaccination: Rr=1.67/1,000,000 injections; rank effect in favor of the first injection (P=.03); complete recovery in 24% (7/29) of cases; median delay onset before day 21=8 days (median age 47, IQR 33-81 years); and no effects of sex. Autoimmune, cardiovascular, or audiovestibular risk factors were present in approximately 29.8% (51/171) of the cases. SSNHL was more often unilateral than bilateral for both mRNA vaccines (P<.001 for tozinameran; P<.003 for elasomeran). There were 13.5% (23/142) of cases of profound hearing loss, among which 74% (17/23) did not recover a serviceable ear. A positive rechallenge was documented for 8 cases. CONCLUSIONS: SSNHL after COVID-19 mRNA vaccines are very rare adverse events that do not call into question the benefits of mRNA vaccines but deserve to be known given the potentially disabling impact of sudden deafness. Therefore, it is essential to properly characterize postinjection SSNHL, especially in the case of a positive rechallenge, to provide appropriate individualized recommendations.

Pharmacovigilance signals from active surveillance of mRNA platform vaccines (tozinameran and elasomeran).

INTRODUCTION: Two severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines, tozinameran/BNT162b2 (Comirnaty®, Pfizer-BioNTech) and elasomeran/mRNA-1273 (Spikevax®, Moderna), were approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) at the end of 2020, less than a year after the start of the coronavirus disease 2019 (COVID-19) pandemic. In France, the health authorities have requested an intensive vaccination campaign, accompanied by a reinforced and active pharmacovigilance surveillance. This surveillance and analysis of real-life data, based on spontaneous reports received by the French Network of Regional PharmacoVigilance Centers (RFCRPV), has enabled to identify numerous pharmacovigilance signals. Some of them, such as myocarditis and heavy menstrual bleeding, have been confirmed as adverse effects of these vaccines. METHOD: We propose a descriptive review of the main pharmacovigilance signals identified by the RFCRPV concerning vaccines from the mRNA platform. RESULTS: Most pharmacovigilance signals were common to both mRNA vaccines: myocarditis, menstrual disorders, acquired haemophilia, Parsonage-Turner syndrome, rhizomelic pseudo-polyarthritis and hearing disorders. Other signals were more specific, such as arterial hypertension with tozinameran or delayed reaction site injection with elasomeran. CONCLUSION: This non-exhaustive review illustrates the experience of RFCRPV in identifying and monitoring pharmacovigilance signals related to mRNA vaccines in France during the COVID-19 pandemics, and the crucial role of pharmacological and clinical expertise in this area. It also highlights the predominant contribution of spontaneous reporting in the generation of pharmacovigilance signals, particularly for serious and rare adverse events not detected before marketing.

Role of spontaneous reporting in investigating the relationship between mRNA COVID-19 vaccines and myocarditis: The French perspective.

AIM OF THE STUDY: Post-mRNA coronavirus diseases 2019 (COVID-19) vaccines myocarditis emerged as a rare adverse effect, particularly in adolescents and young adults, and was labeled as such for both vaccines in the summer of 2021. This study aims to summarize the timeline and process of signal detection, substantiation, and quantification of myocarditis cases related to mRNA vaccines in France. METHODS: The intensive monitoring plan for COVID-19 vaccine safety was based on case-by-case analysis of all cases collected in the French spontaneous reporting database (Base nationale de pharmacovigilance, BNPV). Cases were evaluated by drug safety medical professionals and discussed at a national level for signal detection purposes. Reported cases were compared to the number of vaccine-exposed persons up to September 30th, 2021. Reporting rates (Rr) of myocarditis per 100,000 injections were calculated and stratified according to age, gender, and injection rank of BNT162b2 and mRNA-1273 vaccines. Poisson distribution was used to compute Rrs 95% Confidence Interval (95% CI). RESULTS: The case-by-case analysis detected a possible cluster of myocarditis in April 2021 (5 cases, 4 after the 2nd injection). In June 2021, the signal was substantiated with 12 cases (9 related to BNT162b2, and 3 to mRNA-1273). As of September 2021, almost 73 million BNT162b2 and 10 million mRNA-1273 doses had been injected. The Rr per 100,000 injections was 0.5 (0.5-0.6) for BNT162b2 and 1.1 (95% CI 0.9-1.3) for mRNA-1273. The difference among vaccines was more pronounced after the second injection, particularly in men aged 18-24 years (4.3 [3.4-5.5] for BNT162b2 vs. 13.9 [9.2-20.1] for mRNA-1273) and aged 25-29 years (1.9 [1.2-2.9] vs. 7.0 [3.4-12.9]). CONCLUSION: The study highlighted the role of the spontaneous reporting system in the detection, assessment, and quantification of myocarditis related to m-RNA vaccines. It suggested from September 2021 that mRNA-1273 was reasonably related to a higher risk of myocarditis than BNT162b2 in people under 30, particularly after the second injection.

Pharmacovigilance follow-up of patients in the context of the COVID-19 pandemic.

INTRODUCTION: In the context of COVID-19 pandemic, a national pharmacovigilance survey was set up in March 2020. The purpose of this survey was to ensure continuous monitoring of adverse drug reactions (ADRs) in patients with COVID-19, not only related to the drugs used in this indication but also related to all drugs administered to these patients or suspected of having promoted the infection. MATERIAL AND METHODS: This descriptive study was based on data extracted from the French Pharmacovigilance Database from 1 January 2020 to 30 September 2021. Misuse was also analysed through the MESANGE project. The ADRs were classified according to three groups: "drugs used to treat COVID-19", "other drugs administered to COVID-19 positive patients" and "drugs suspected of having promoted COVID-19". The data were also presented according to 2 periods (period one was from January to June 2020 and period two from July 2020 onwards). RESULTS: Among 2189 included cases, 67.1% were serious. Cases were mainly related to "other drugs administrated to COVID-19 positive patients" (58.5%) followed by "drugs used to treat COVID-19" (33.7%) and "drugs suspected of having promoted COVID-19" (7.8%). Drugs used to treat COVID-19 and their main safety profile were different depending on the period: mostly hydroxychloroquine (51%) with heart injury and lopinavir/ritonavir (42%) with liver injury for the first period, and dexamethasone (46%) with hyperglycemia and tocilizumab (28%) with liver injury for the second period. The drugs suspected of worsening COVID-19 differed in both periods especially for non-steroidal anti-inflammatory drugs mainly reported in period 1 (41.5% versus 8.2% in period 2). Other immunosuppressive drugs were in the majority in the second period (85.7%), with mainly methotrexate (15.3%), anti-CD20 (15.3%) and anti-TNF alpha (10.5%). No confirmed safety signal was identified among other drugs administered to patients with COVID-19. The profile of ADRs and suspected drugs was similar between the 2 periods. The study of misuse in outpatient settings identified in both periods mainly hydroxychloroquine, azithromycin, ivermectin and zinc±vitamin C. DISCUSSION: This survey, based on real-time pharmacological and medical assessment of ADRs and weekly meetings in a specific national committee, made it possible to identify relevant safety signals which contribute to patient care with no delay. The main safety signal highlighted was serious cardiac damage under hydroxychloroquine, alone or combined with azithromycin and also with lopinavir/ritonavir. This signal has contributed to the evolution of the recommendations for these 2 drugs. The methodology of this survey has been taken over and is still going on for the pharmacovigilance monitoring of vaccines against COVID-19, for monoclonal antibodies used against COVID-19 and also for Paxlovid® (nirmatrelvir/ritonavir) which benefit from dedicated surveys.

[HIV preexposure prophylaxis with tenofovir disoproxil fumarate/emtricitabine: What about safety?] / Utilisation de TRUVADA® en prophylaxie préexposition : analyse des bases de vigilance et revue de la littérature.

INTRODUCTION: Pre-exposure prophylaxis (PrEP) is a combination of antiretroviral regimen, tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) that has been shown to prevent HIV transmission. It had been regulated through a temporary recommendation use since December 2015 and had marketing authorization in France since March 2017. As, this product is proposed for adults and adolescents safe from HIV but at high risk of infection, the question is to know if there is a safety concern about this use. METHODS: A request has been made in the French national pharmacovigilance database (ANPV) and VIGILYZE for an extraction of all cases containing TDF/FTC as suspect drugs in PrEP use. In the second part, we did a literature review in PubMED with MeSH terms and an analysis of the results of the American, English and French initial clinical trials was performed. RESULTS: In both database, 808 cases correspond to an indication of HIV prexposure prophylaxis who represent 2058 adverse effects (AEs) mainly distributed in gastro-intestinal disorders (38.5%), general disorders (16.8%) and 62 cases of seroconversion. We identify 24% of unexpected AEs including 12% of serious AEs in the French database. In literature review, there are no unexpected AEs published, the AEs are mainly gastro-intestinal disorders. There was no significant difference in the AE profile compared to the HIV-infected population treated with TDF/FTC. CONCLUSION: Data from the ANPV, combined with data from the worldwide pharmacovigilance database, show that the most commonly observed AEs are gastrointestinal, mainly nausea, vomiting and diarrhea. A significant number of asthenia and fatigue are also observed. These AEs are well described in the SMPc. However, we have little data, which can be explained by a probable under-reporting of AEs. We identify 24% of unexpected and potentially serious adverse effects in France mainly among chemsex users. Based on these results, our study confirms the safety of PrEP.

Epidemiology and economic burden of "serious" adverse drug reactions: Real-world evidence research based on pharmacovigilance data.

AIM OF THE STUDY: Serious adverse drug reactions account for 3.6% of French hospital admissions. Of these, 48.5% are, at least potentially, preventable. The first aim of post-marketing pharmacovigilance is to detect adverse drug reactions as a safety signal to improve patients' safety. Thus, this study describes the epidemiology of "serious" adverse drug reactions reported between 2015 and 2018 to a regional pharmacovigilance centre and assesses their economic burden. METHODS: All "serious" adverse drug reactions reported to a regional pharmacovigilance centre during the four-year study period were collected and cost associated. Only congenital anomalies related to "serious" adverse drug reactions were excluded. RESULTS: All 2585 "serious" adverse drug reactions reported are related to 1242 "serious" individual case safety reports. Among 58.1% of them, patients required hospital admission or a visit to the emergency room with a median cost estimated to €3725 per "serious" individual case safety report. The most "serious" adverse drug reactions reported involved gastrointestinal disorders. Fifteen percent of the imputed drugs had a narrow therapeutic index and the most frequently drug was fluindione. Finally, high relationships with an economic burden were observed for ages over or equal to 65, and imputed drugs from "Blood and Blood-Forming Organs" and "Anti-infectives for systemic use" therapeutic groups. CONCLUSION: This study provides news data on epidemiology and cost of "serious" adverse drug reactions completing the existing literature. On a regional scale, pharmacovigilance real world data could be interesting for pharmacist clinicians in common practice to improve the good use of drugs.

Features of Inflammatory Heart Reactions Following mRNA COVID-19 Vaccination at a Global Level.

Myocarditis and pericarditis may constitute adverse reactions of mRNA coronavirus disease 2019 (COVID-19) vaccines. This study aimed to document these reactions and to assess the association with patient sex and age. This is as an observational retrospective study using a case-non-case design (also called disproportionality study) on inflammatory heart reactions reported with mRNA COVID-19 vaccines within the World Health Organization (WHO) global safety database (VigiBase), up to June 30, 2021. Results are expressed using reporting odds ratios (RORs) and their 95% confidence interval (95% CI). Of 716,576 reports related to mRNA COVID-19 vaccines, 2,277 were cases of inflammatory heart reactions, including 1241 (55%) myocarditis and 851 (37%) pericarditis. The main age group was 18-29 years (704, 31%), and mostly male patients (1,555, 68%). Pericarditis onset was delayed compared with myocarditis with a median time to onset of 8 (3-21) vs. 3 (2-6) days, respectively (P = 0.001). Regarding myocarditis, an important disproportionate reporting was observed in adolescents (ROR, 22.3, 95% CI 19.2-25.9) and in 18-29 years old (ROR, 6.6, 95% CI 5.9-7.5) compared with older patients, as well as in male patients (ROR, 9.4, 95% CI 8.3-10.6). Reporting rate of myocarditis was increased in young adults and adolescents. Inflammatory heart reactions may rarely occur shortly following mRNA COVID-19 vaccination. Although an important disproportionate reporting of myocarditis was observed among adolescents and young adults, particularly in male patients, reporting rates support a very rare risk, that does not seem to compromise the largely positive benefit-risk balance of these vaccines. Furthermore, this study confirmed the value of disproportionality analyses for estimation of relative risks among subgroups of patients.

French organization for the pharmacovigilance of COVID-19 vaccines: A major challenge.

In this special issue, we present the main highlights of the first weeks of pharmacovigilance monitoring of coronavirus disease 2019 (COVID-19) vaccines in this unprecedented situation in France: the deployment of a vaccination during an epidemic period with the aim of vaccinating the entire population and the intense pharmacovigilance and surveillance of these vaccines still under conditional marketing authorizations. In this unprecedented situation, the cross approach and interaction between the French pharmacovigilance network and French National Agency for the Safety of Medicines and Health Products (ANSM) has been optimized to provide a real-time safety related to COVID-19 vaccines. Every week, pair of regional pharmacovigilance centers gathered safety data from the French pharmacovigilance network, to acutely expertise all the adverse drug reactions (ADRs) reported with each COVID-19 vaccine within a direct circuit with ANSM. Results of this expertise are presented and discussed with ANSM in order to raise safety signals and take appropriate measures if necessary. These reports are then published online. At the 25th of March 2021, more than 9 815 000 doses were injected and 20,265 ADRs were reported, mostly non-serious (76%). Several potential or confirmed signals were raised at the european level for those vaccines and others ADRs are under special attentions. This underlines the adaptiveness of the French pharmacovigilance system to both the identification of new patient profiles experiencing ADRs and the evolution of the vaccine strategy. Such an efficiency is necessary to manage a careful and acute surveillance of these new COVID-19 vaccines for and to face the pandemic at the same time.

REview of potentially inappropriate MEDIcation pr[e]scribing in Seniors (REMEDI[e]S): French implicit and explicit criteria.

PURPOSE: To establish a consensus on both explicit and implicit criteria in order to identify potentially inappropriate prescribing (PIP) in French older people aged 75 years and over or 65 years and over with multimorbidity. METHODS: Fifteen experts in geriatrics, general practice, pharmacy, and clinical pharmacology were involved in a two-round Delphi survey to assess preliminary explicit and implicit criteria based on an extensive literature review and up-to-date evidence data. Experts were asked to rate their level of agreement using a 5-level Likert scale for inclusion of criteria and also for rationale and therapeutic alternatives. A consensus was considered as reached if at least 75% of the experts rated criteria as "strongly agreed" or "agreed." RESULTS: The new tool included a seven-step algorithm (implicit criteria) encompassing the three main domains that define PIP (i.e. overprescribing, underprescribing, and misprescribing) and 104 explicit criteria. Explicit criteria were divided into 6 tables related to inappropriate drug duplications (n = 7 criteria), omissions of medications and/or medication associations (n = 16), medications with an unfavourable benefit/risk ratio and/or a questionable efficacy (n = 39), medications with an unsuitable dose (n = 4) or duration (n = 6), drug-disease (n = 13), and drug-drug interactions (n = 19). CONCLUSION: The REMEDI[e]S tool (REview of potentially inappropriate MEDIcation pr[e]scribing in Seniors) is an original mixed tool, adapted to French medical practices, aimed at preventing PIP both at the individual level in clinical practice and the population level in large-scale studies. Therefore, its use could contribute to an improvement in healthcare professionals' prescribing practices and safer care in older adults.

Ocular Safety Profile of BRAF and MEK Inhibitors: Data from the World Health Organization Pharmacovigilance Database.

PURPOSE: BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) significantly improved metastatic melanoma prognosis. Ocular adverse effects (OAEs) represent an uncommon but disabling toxicity of these drugs. We aimed to characterize the ocular safety profile of BRAFi or MEKi and to detect possible safety signals. METHODS: We performed a retrospective, observational, pharmacovigilance study using VigiBase, the World Health Organization global safety database. Ocular adverse effects were classified according to the eye segments and the inflammatory pattern based on the Standardization of Uveitis Nomenclature. Associations among BRAFi monotherapy, MEKi monotherapy, and BRAFi+MEKi combination therapy and OAE reporting were assessed using disproportionality analysis. Results were expressed with the reporting odds ratio (ROR) and its 95% confidence interval (CI). RESULTS: From January 2010 to October 2019, 1568 OAE cases were reported with BRAFi or MEKi. Among them, 1006 cases with sufficient data were included, corresponding to 310 (30.8%), 124 (12.3%), and 572 (56.9%) cases reported with BRAFi, MEKi, or BRAFi+MEKi combination therapy, respectively. BRAF inhibitor monotherapy was significantly associated with the reporting of iris and ciliary body abnormalities (ROR, 8.7; 95% CI, 6.0-12.5), diffuse abnormalities (ROR, 7.1; 95% CI, 5.4-9.4), anterior uveitis (ROR, 8.6; 95% CI, 6.0-12.1), and panuveitis (ROR, 7.1; 95% CI, 5.4-9.4). MEK inhibitor monotherapy was associated with the reporting of retinal and choroid abnormalities (ROR, 9.5; 95% CI, 7.4-12.2), diffuse abnormalities (ROR, 2.5; 95% CI, 1.1-6.1), and panuveitis (ROR, 2.5; 95% CI, 1.1-6.1). Combinations of BRAFi and MEKi therapies were associated with OAEs from both drugs, with a possible synergistic or additive effect for diffuse abnormalities and panuveitis. CONCLUSIONS: Our study characterizes the ocular safety profile of BRAFi and MEKi. We identify possible safety signals for several OAEs not previously reported with BRAFi and MEKi. Our data provide the rationale for a personalized management of OAE in patients with BRAFi+MEKi combination therapy according to the type of ocular reaction.

Mapping of drug-related problems among older adults conciliating medical and pharmaceutical approaches.

PURPOSE: To lay the fundamentals of drug-related problems (DRPs) in older adults, and to organize them according to a logical process conciliating medical and pharmaceutical approaches, to better identify the causes and consequences of DRPs. MATERIALS AND METHODS: A narrative overview. RESULTS: The causes of DRPs may be intentional or unintentional. They lie in poor prescription, poor adherence, medication errors (MEs) and substance use disorders (SUD). Poor prescription encompasses sub-optimal or off-label drug choice; this choice is either intentional or unintentional, often within a polypharmacy context and not taking sufficiently into account the patient's clinical condition. Poor adherence is often the consequence of a complicated administration schedule. This review shows that MEs are not the most frequent causes of DRPs. SUD are little studied in older adults and needs to be more investigated because the use of psychoactive substances among older people is frequent. Prescribers, pharmacists, nurses, patients, and caregivers all play a role in different causes of DRPs. The potential deleterious outcomes of DRPs result from adverse drug reactions and therapeutic failures. These can lead to a negative benefit-risk ratio for a given treatment regimen. DISCUSSION/CONCLUSION: Interdisciplinary pharmacotherapy programs show significant clinical impacts in preventing or resolving adverse drug events and, suboptimal responses. New technologies also seem to be interesting solutions to prevent MEs. Better communication between healthcare professionals, patients and their caregivers would ensure greater safety and effectiveness of treatments.

Risk of scleroderma according to the type of immune checkpoint inhibitors.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are associated with immune-related adverse events (irAEs). Among them, ICIs-induced systemic sclerosis (SSc) is poorly known. METHODS: To better characterize this irAE, our comprehensive approach combined the description of ICIs-induced scleroderma cases, the systematic review of the literature and the analysis of VigiBase, the WHO pharmacovigilance database. RESULTS: We identified two cases with underlying limited cutaneous SSc who presented a dramatic increase in the skin thickening following pembrolizumab, associated with scleroderma renal crisis in one case. In the literature, four cases of scleroderma and four cases of morphea have been reported with pembrolizumab or nivolumab. None following ipilimumab, atezolizumab or durvalumab were retrieved. Skin changes appeared or worsened more quickly with pembrolizumab than nivolumab, and had different patterns between both drugs. Patients with generalized skin changes required high-dose prednisone to improve skin thickening. Among the 2527 scleroderma cases identified in VigiBase, 35 were associated with ICIs. Nivolumab and pembrolizumab showed a disproportionality in scleroderma reporting. No disproportionality was found for ipilimumab, atezolizumab or durvalumab. CONCLUSION: The risk of scleroderma or fibrosis extension in SSc patients should be considered when initiating anti-PD-1 agents. It suggests the role of PD-1/PD-L1 interaction in the pathophysiology of SSc.

Liquid formulation of ifosfamide increased risk of encephalopathy: A case-control study in a pediatric population.

BACKGROUND: Several clusters of encephalopathy occurred after the market change from Holoxan® (ifosfamide lyophilized powder) to Ifosfamide EG® (liquid formulation) and justified a formal survey in 2015. In June 2016, the regulatory authority decided to apply a precautionary measure in reducing the shelf life of Ifosfamide EG® at 7 months. One-year study from spontaneous reports lead to suspect a potential residual risk. Due to the many limitations associated with spontaneous notifications, we performed a multicentric observational study, aiming to better explore this pharmacovigilance signal. METHODS: We performed a case-control study in pediatric oncology Departments of 25 university hospitals between July 1st, 2016 and July 1st, 2018. All children (<18 y.o.) receiving liquid formulation or lyophilized powder formulation during the study period were included. Patients with at least one occurrence of encephalopathy were considered as cases. Logistic regression model was used to estimate the odds ratio of encephalopathy between exposure groups. RESULTS: During the study period, 52 cases and 495 controls were included. A residual over-risk of encephalopathy was associated with ifosfamide 7-month shelf-life liquid formulation compared to lyophilized powder (adjusted OR 1.91, 95% CI: 1.03-3.53). CONCLUSIONS: Observed difference does not seem to be related to the pathology treated, the doses used, the co-medications, a meningeal localization and/or an irradiation of the central nervous system. This study confirms data from spontaneous reports that led to the precautionary measure for the liquid formulation. Even if the risk of encephalopathy seems reduced, our study suggests the persistence of a residual risk of encephalopathy associated with liquid formulation compared to the lyophilized powder.