The REporting of A Disproportionality Analysis for DrUg Safety Signal Detection Using Individual Case Safety Reports in PharmacoVigilance (READUS-PV): Explanation and Elaboration.

In pharmacovigilance, disproportionality analyses based on individual case safety reports are widely used to detect safety signals. Unfortunately, publishing disproportionality analyses lacks specific guidelines, often leading to incomplete and ambiguous reporting, and carries the risk of incorrect conclusions when data are not placed in the correct context. The REporting of A Disproportionality analysis for drUg Safety signal detection using individual case safety reports in PharmacoVigilance (READUS-PV) statement was developed to address this issue by promoting transparent and comprehensive reporting of disproportionality studies. While the statement paper explains in greater detail the procedure followed to develop these guidelines, with this explanation paper we present the 14 items retained for READUS-PV guidelines, together with an in-depth explanation of their rationale and bullet points to illustrate their practical implementation. Our primary objective is to foster the adoption of the READUS-PV guidelines among authors, editors, peer reviewers, and readers of disproportionality analyses. Enhancing transparency, completeness, and accuracy of reporting, as well as proper interpretation of their results, READUS-PV guidelines will ultimately facilitate evidence-based decision making in pharmacovigilance.

The Reporting of a Disproportionality Analysis for Drug Safety Signal Detection Using Individual Case Safety Reports in PharmacoVigilance (READUS-PV): Development and Statement.

BACKGROUND AND AIM: Disproportionality analyses using reports of suspected adverse drug reactions are the most commonly used quantitative methods for detecting safety signals in pharmacovigilance. However, their methods and results are generally poorly reported in published articles and existing guidelines do not capture the specific features of disproportionality analyses. We here describe the development of a guideline (REporting of A Disproportionality analysis for drUg Safety signal detection using individual case safety reports in PharmacoVigilance [READUS-PV]) for reporting the results of disproportionality analyses in articles and abstracts. METHODS: We established a group of 34 international experts from universities, the pharmaceutical industry, and regulatory agencies, with expertise in pharmacovigilance, disproportionality analyses, and assessment of safety signals. We followed a three-step process to develop the checklist: (1) an open-text survey to generate a first list of items; (2) an online Delphi method to select and rephrase the most important items; (3) a final online consensus meeting. RESULTS: Among the panel members, 33 experts responded to round 1 and 30 to round 2 of the Delphi and 25 participated to the consensus meeting. Overall, 60 recommendations for the main body of the manuscript and 13 recommendations for the abstracts were retained by participants after the Delphi method. After merging of some items together and the online consensus meeting, the READUS-PV guidelines comprise a checklist of 32 recommendations, in 14 items, for the reporting of disproportionality analyses in the main body text and four items, comprising 12 recommendations, for abstracts. CONCLUSIONS: The READUS-PV guidelines will support authors, editors, peer-reviewers, and users of disproportionality analyses using individual case safety report databases. Adopting these guidelines will lead to more transparent, comprehensive, and accurate reporting and interpretation of disproportionality analyses, facilitating the integration with other sources of evidence.

Use of sodium-glucose cotransporter-2 inhibitors in France: Analysis of French nationwide health insurance database.

AIM: Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) have been commercialized in France for type 2 diabetes since April 2020 and later for heart and renal diseases. Given the recent developments in treating diabetes and the widening of SGLT-2i indications, we aimed to study changes in the use of glucose-lowering drugs in France and to characterize SGLT-2i new users. METHODS: We performed a nationwide utilization study using the French health insurance database. Trends in incidence and prevalence of glucose-lowering drug use were assessed by a repeated cross-sectional study in 2019 and 2021. A cohort study of incident SGLT-2i users was then conducted to describe patient characteristics and the strategy for treating diabetes. RESULTS: The prevalence of SGLT-2i use gradually reached 0.1% in the third quarter of 2021 and increased more significantly to 0.2% thereafter. SGLT-2i became the second most prescribed glucose-lowering drug class after metformin at the end of 2021 (0.1%). Among the cohort of 125 387 SGLT-2i new users (mean age 65.0 years; 60.1% of men), 87.6% presented a diabetic comorbidity. The patient profile changed over the study period with an increasing proportion of patients with cardiovascular (28.7% in 2020 vs. 40.2% in 2021) or renal (7.7% in 2020 vs. 11.8% in 2021) comorbidities at initiation. The main combinations used at SGLT-2i initiation were metformin (12.5%) and metformin plus dipeptidyl peptidase-4 inhibitors (8.1%). One-year probability of SGLT-2i persistence was estimated to be 55%. CONCLUSION: The expansion of indications for SGLT-2i and the broadening of the target population make it essential to assess the reasons for discontinuation and review their safety profile.

Invasive fungal infection incidence and risk factors in patients receiving ibrutinib in real-life settings: A nationwide population-based cohort study.

BACKGROUND: Data on the risk of invasive fungal infections (IFI) with ibrutinib treatment are scarce. OBJECTIVES: This study aimed to determine IFI incidence and risk factors in ibrutinib-treated patients in real-life settings. METHODS: We constituted a cohort of ibrutinib incident users in the French National Healthcare Database. All patients ≥18 years with a first dispensing of ibrutinib between 21 November 2014 and 31 December 2019 were included. Patients were followed from the cohort entry date until IFI, ibrutinib discontinuation, death, or 31 December 2020, whichever came first. The cumulative incidence function method was used to estimate the probability of IFI accounting for competing risk of death. A multivariate cause-specific Cox proportional hazards model was used to assess independent IFI risk factors. RESULTS: Among 6937 ibrutinib-treated patients, 1-year IFI cumulative incidence was 1.3%, with invasive aspergillosis being the most frequent. Allogenic or autologous stem cell transplantation (ASCT) (hazard ratio [HR] 3.59, 95% confidence interval [1.74; 7.41]), previous anticancer treatment (HR 2.12, CI 95% [1.34; 3.35]) and chronic respiratory disease (HR 1.66, [1.03; 2.67]) were associated with higher risk of IFI. Besides neutropenia and corticosteroids, use of anti-CD20 agents was significantly more frequent in patients having experienced IFI (HR 3.68, [1.82; 7.45]). CONCLUSIONS: In addition to patients with ASCT history, severe neutropenia or treated with corticosteroids, our findings support active surveillance of IFIs in those with chronic respiratory disease, previously treated, or treated with anti-CD20 agents in combination with ibrutinib. Further studies are needed to optimise IFI prophylaxis in these patient subgroups.

Impact of Covid-19 Vaccination on Spontaneous Pharmacovigilance Reporting in France.

INTRODUCTION: In 2021, the massive Covid-19 vaccination campaign in France was accompanied by an intensified pharmacovigilance monitoring of their potential adverse drug reactions. The importance of this reporting might have led to an important selective reporting and overloading of Pharmacovigilance Centres, delaying the recording of some reports in the national pharmacovigilance database. In this context, we aimed to evaluate the impact of the Covid-19 vaccination campaign in France and related reports on spontaneous reporting of adverse drug reactions that were not related to the Covid-19 vaccine. METHODS: We performed time-series analyses considering the monthly number of adverse drug reactions reported between January 1, 2018 and April 30, 2022 using the French Pharmacovigilance database. The impact of the Covid-19 vaccination campaign on the monthly reporting not Covid-19 vaccine related was estimated using interrupted time-series. January 2021, marking the start of the campaign, was the intervention date in the models. Analyses were run globally first considering all adverse drug reaction reports, and second according to notifier type and to case seriousness. RESULTS: We included 170,294 reports registered in the French Pharmacovigilance database between January 1, 2018 and April 30, 2022 that were not Covid-19 vaccine-related. Among these, 77,067 (45.3%) were serious and 146,683 (86.1%) had been reported by health care professionals. The campaign start was associated with a nearly 35.0% decrease in average monthly reporting that was not Covid-19 vaccine-related, with a significant level decrease in the monthly number of reports of -658.0 (p < 10-3) immediately after the vaccination campaign start and a subsequent slope decrease of -50.0 (p < 10-3). This decrease was mainly due to a significant level and slope decrease (level: -739.2 p < 10-3; slope: -39 [p < 10-2]) for health care professional reports. A similar level decrease was found for the monthly number of both serious and non-serious reports (-402.3, p < 10-3; and -311.9, p = 10-2, respectively). According to the ATC 1 level, the decrease in the monthly number of reports showed similar patterns for all drugs. However, a potential increase in the number of serious reports suspecting antineoplastic and immunomodulating drugs (ATC L) or drugs targeting blood was observed (ATC B). CONCLUSION: Our study showed a significant impact of the Covid-19 campaign vaccination in the reporting of adverse drug reactions that were not Covid-19 vaccine-related, of roughly 35%. This leads to a loss of information regarding the monitoring of drug safety that could have impacted the system capacity to detect safety signals for drugs other than Covid-19 vaccines.

Statin treatment is not associated with an increased risk of adrenal insufficiency in real-world setting.

Introduction: Statins could reduce the synthesis of steroid hormones, thereby could cause adrenal insufficiency. We investigated this risk in a large nationwide database. Methods: We conducted a nested case-control study using a cohort of individuals affiliated to the French health insurance system in 2010, ≥18y and without adrenal insufficiency history. Each case had a first event of adrenal insufficiency between 2015 and 2017 and was matched to up to ten controls on age, sex, and prior treatment with corticosteroids. Statin exposure was measured over the five years preceding the index date, considering a six-month censoring lag-time. Association was estimated using a conditional logistic regression adjusted for confounders included in a disease risk score. Analyses were stratified on age, sex and corticosteroid history of use. Results: 4 492 cases of adrenal insufficiency were compared with 44 798 controls (median age 66y, 58% women), of which 39% vs. 33% were exposed to statins, respectively. No association between statin use and adrenal insufficiency was found when adjusting the model for confounders (adjusted odds ratio 0.98; 95% confidence interval 0.90-1.05). These results were consistent regardless of the exposure definition and stratifications considered. Conclusion: Statin-related adrenal insufficiency risk, if any, seems to be very limited and does not compromise the benefit of statin treatment.

Trajectories of Benzodiazepine Use among Older Adults from a Concordance-with-Guidelines Perspective: A Nationwide Cohort Study.

BACKGROUND AND OBJECTIVE: Benzodiazepines (including zolpidem and zopiclone) are often associated with higher-than-recommended intake and durations of use, especially in older adults. The objective of this study was to characterize trajectories of benzodiazepine use according to recommended patterns in older adults, and to assess predictors of the risk of developing each of these trajectories. METHODS: Using the French Health Insurance database, we constituted a cohort of adults aged ≥ 65 years who initiated benzodiazepines in 2007 and were followed for up to 8 years. Concordance with benzodiazepine use guidelines was assessed on a quarterly basis according to a "concordance-with-guideline score" with values 1-5. Group-based trajectory modeling was then applied as implemented in the Proc Traj procedure in SAS to define guideline-concordant trajectories based on seven baseline patient-centered characteristics: sex, complementary health insurance coverage, treated alcohol and tobacco use disorder, polypharmacy, hospital stay, and registered chronic diseases. RESULTS: Among 5080 new users (64.1% women, median age 74 years), six trajectories of benzodiazepine use were identified. Three, representing 70% of users, were concordant with guidelines, whereas three implied non-concordant benzodiazepine use for part or all of the benzodiazepine use follow-up. Polymedicated patients were more prone to develop chronic non-guideline-concordant initially guideline-concordant use, whereas those with a history of long-term disease and hospitalization were more likely to develop chronic non-guideline-concordant use. The number of prescribers during the first quarter, number of daily defined doses, use of loperamide, and use of psychostimulants were associated with a higher risk of developing an initial and persistent non-guideline-concordant use. Treatment initiation by a psychiatrist, initial use of World Health Organization (WHO) step-2 opioids and non-benzodiazepine anxiolytics or sedatives were associated with a higher risk of late non-guideline-concordant use. CONCLUSIONS: Concordance with guidelines varied over time during benzodiazepine use in older adults. A third of these adults will hypothetically follow one of the identified non-guideline-concordant trajectories, consisting of initial and/or late non-guideline concordance. This was associated with modifiable and nonmodifiable factors that clinicians should be aware of for tailoring the monitoring of patients.

Will the future of pharmacovigilance be more automated?

INTRODUCTION: Artificial intelligence (AI) based tools offer new opportunities for pharmacovigilance (PV) activities. Nevertheless, their contribution to PV needs to be tailored to preserve and strengthen medical and pharmacological expertise in drug safety. AREAS COVERED: This work aims to describe PV tasks in which the contribution of AI and intelligent automation (IA) tools is required, in the context of a continuous increase of spontaneous reporting cases and regulatory tasks. A narrative review with expert selection of pertinent references was performed through Medline. Two areas were covered, management of spontaneous reporting cases and signal detection. PERSPECTIVE: The use of AI and IA tools will assist a large spectrum of PV activities, both in public and private PV systems, in particular for tasks of low added value (e.g. initial quality check, verification of essential regulatory information, search for duplicates). Testing, validating, and integrating these tools in the PV routine are the actual challenges for modern PV systems, to guarantee high-quality standards in terms of case management and signal detection.

Bleeding risk with concurrent use of anticoagulants and ibrutinib: A population-based nested case-control study.

Data regarding the safety of co-administration of ibrutinib with anticoagulants in real-life settings are scarce. Using a nationwide database, we conducted a nested case-control study in a cohort of new users of ibrutinib to assess the risk of clinically relevant bleeding (CRB) associated with anticoagulation. Cases were patients with a diagnosis of CRB, defined as hospitalization with a diagnosis of bleeding. The date of CRB constituted the index date. Up to four controls were matched on sex, age at index date and duration of follow-up. The risk of CRB associated with anticoagulation in patients receiving ibrutinib was estimated using conditional logistic regression models, providing odds ratios (OR) adjusted for risk factors of bleeding. Among 614 cases and 2407 matched controls, the risk of CRB was significantly higher in patients receiving both ibrutinib and anticoagulants (adjusted OR [aOR] 2.54, confidence interval [CI] 95% [1.94; 3.32]). When considering anticoagulant class, aOR was 1.99 (CI 95% [1.19; 3.33]) for VKA, 2.48 (CI 95% [1.76; 3.47]) for direct oral anticoagulants and 3.40 (CI 95% [2.01; 5.75]) for parenteral anticoagulants. In conclusion, this study found a 2.5-fold increased risk of CRB in patients receiving both ibrutinib and anticoagulants in real-life settings, and similar aOR among oral anticoagulants.

Mapping Strategies to Assess and Increase the Validity of Published Disproportionality Signals: A Meta-Research Study.

BACKGROUND AND AIM: Disproportionality analysis is traditionally used in spontaneous reporting systems to generate working hypotheses about potential adverse drug reactions: the so-called disproportionality signals. We aim to map the methods used by researchers to assess and increase the validity of their published disproportionality signals. METHODS: From a systematic literature search of published disproportionality analyses up until 1 January 2020, we randomly selected and analyzed 100 studies. We considered five domains: (1) rationale for the study, (2) design of disproportionality analyses, (3) case-by-case assessment, (4) use of complementary data sources, and (5) contextualization of the results within existing evidence. RESULTS: Among the articles, multiple strategies were adopted to assess and enhance the results validity. The rationale, in 95 articles, was explicitly referred to the accrued evidence, mostly observational data (n = 46) and regulatory documents (n = 45). A statistical adjustment was performed in 34 studies, and specific strategies to correct for biases were implemented in 33 studies. A case-by-case assessment was complementarily performed in 35 studies, most often by investigating temporal plausibility (n = 26). Complementary data sources were used in 25 articles. In 78 articles, results were contextualized using accrued evidence from the literature and regulatory documents, the most important sources being observational (n = 45), other disproportionalities (n = 37), and case reports (n = 36). CONCLUSIONS: This meta-research study highlighted the heterogeneity in methods and strategies used by researchers to assess the validity of disproportionality signals. Mapping these strategies is a first step towards testing their utility in different scenarios and developing guidelines for designing future disproportionality analysis.

Risk of suicide attempt and suicide associated with benzodiazepine: A nationwide case crossover study.

BACKGROUND: Previous studies that found an association between benzodiazepines and suicidal behaviours were confounded by indication bias. AIMS: To limit this bias, a case crossover study (CCO) was conducted to estimate the risk of suicide attempt and suicide associated with benzodiazepines. METHOD: Patients ≥16 years, with hospitalised suicide attempt or suicide between 2013 and 2016, and at least one benzodiazepine dispensing within the 120 days before their act were selected in the nationwide French reimbursement healthcare system databases (SNDS). For each patient, frequency of benzodiazepine dispensing was compared between a risk period (days -30 to -1 before the event) and two matched reference periods (days -120 to -91, and -90 to -61). RESULTS: A total of 111,550 individuals who attempted suicide and 12,312 suicide victims were included, of who, respectively, 77,474 and 7958 had recent psychiatric history. Benzodiazepine dispensing appeared higher in the 30-day risk period than in reference ones. The comparison yielded adjusted odds ratios of 1.74 for hospitalised suicide attempt (95% confidence interval 1.69-1.78) and 1.45 for suicide (1.34-1.57) in individuals with recent psychiatric history, and of 2.77 (2.69-2.86) and 1.80 (1.65-1.97) for individuals without. CONCLUSION: This nationwide study supports an association between recent benzodiazepine use and both suicide attempt and suicide. These results strengthen the need for screening for suicidal risk carefully before initiation and during treatment when prescribing benzodiazepines. REGISTRATION NO: EUPAS48070 (http://www.ENCEPP.eu).

Impact of COVID-19 epidemic on antihypertensive drug treatment disruptions: results from a nationwide interrupted time-series analysis.

Background: The COVID-19 epidemic has disrupted care and access to care in many ways. It was accompanied by an excess of cardiovascular drug treatment discontinuations. We sought to investigate a deeper potential impact of the COVID-19 epidemic on antihypertensive drug treatment disruptions by assessing whether the epidemic induced some changes in the characteristics of disruptions in terms of duration, treatment outcome, and patient characteristics. Methods: From March 2018 to February 2021, a repeated cohort analysis was performed using French national health insurance databases. The impact of the epidemic on treatment discontinuations and resumption of antihypertensive medications was assessed using preformed interrupted time series analyses either on a quarterly basis. Results: Among all adult patients on antihypertensive medication, we identified 2,318,844 (18.7%) who discontinued their antihypertensive treatment during the first blocking period in France. No differences were observed between periods in the characteristics of patients who interrupted their treatment or in the duration of treatment disruptions. The COVID-19 epidemic was not accompanied by a change in the proportion of patients who fully resumed treatment after a disruption, neither in level nor in trend/slope [change in level: 2.66 (-0.11; 5.42); change in slope: -0.67 (-1.54; 0.20)]. Results were similar for the proportion of patients who permanently discontinued treatment within 1 year of disruption [level change: -0.21 (-2.08; 1.65); slope change: 0.24 (-0.40; 0.87)]. Conclusion: This study showed that, although it led to an increase in cardiovascular drug disruptions, the COVID-19 epidemic did not change the characteristics of these. First, disruptions were not prolonged, and post-disruption treatment outcomes remained unchanged. Second, patients who experienced antihypertensive drug disruptions during the COVID-19 outbreak were essentially similar to those who experienced disruptions before it.

Drug-Drug Interactions and the Risk of Emergency Hospitalizations: A Nationwide Population-Based Study.

BACKGROUND: Several studies suggest a significant risk of hospitalization because of drug-drug interactions in the general population. However, to our knowledge, this risk has never been measured precisely in a large population. OBJECTIVE: We aimed to estimate the risk of emergency hospitalization associated with exposure to the contraindicated concomitant use of interacting drugs in the general population. METHODS: A self-controlled case-series analysis was carried out on a cohort of 150,000 subjects randomly selected from the French national health insurance database, between 01/01/2016 and 31/12/2016. Exposure to the contraindicated concomitant use of interacting drugs was defined as the overlapping period of dispensings of drugs contraindicated because of clinically meaningful drug-drug interactions. The main outcome, incidence rate ratios, comparing the incidence rate of emergency hospitalizations during each category of exposure time periods with that during the reference period, was estimated using the conditional Poisson regression model. RESULTS: Over the study period, 967 subjects were exposed to at least one contraindicated concomitant use of interacting drug and 177 had been exposed and presented at least one emergency hospitalization. Compared to the unexposed follow-up time, the risk of emergency hospitalization increased during exposure to contraindicated concomitant use of interacting drug periods (incidence rate ratio: 2.41; 95% confidence interval 1.55-3.76). This could translate into 7200 (4500-8900) potentially preventable emergency hospitalizations yearly in France. CONCLUSIONS: We evidenced an almost 2.5-fold increase in the risk of emergency hospitalizations during periods of exposure to contraindicated concomitant use of interacting drugs, with a potential public health impact exceeding 7000 preventable hospitalizations yearly in France. These results confirm the need to reinforce training in prescription practices and tools for prevention concerning contraindicated concomitant use of interacting drugs. These would especially concern drugs involved in an increase in long QT syndrome when associated such as citalopram, and highly prescribed drugs with a risk of overdose if co-prescribed with cytochrome P450 inhibitors, such as antigout and lipid-lowering drugs.

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.

Use of psychotropic drugs in the elderly in France: Are we condemned to remain at high tide?

Psychotropics are widely used drugs, especially in the elderly, especially in France. This, and the risks associated to their use, logically led to concerns that resulted in numerous studies, reports, and regulatory actions intending to limit this use. This review objective was to provide an overview of psychotropic use in elderly subjects in France for antipsychotics, antidepressants, and benzodiazepines and related drugs. The narrative review performed is structured in two parts. The first reminds the initial steps of psychotropic use monitoring in the general French population. The second provides information on psychotropic use in elderly in France using the latest open data released by the French Health Insurance system and processed using the dedicated DrugSurv tool developed within the DRUGS-SAFE® and DRUGS-SAFE® programs. This was completed examining the most recent studies regarding psychotropic use in elderly in France, whether they consisted in publications or reports. At least before the COVID-19 epidemic, decreases in psychotropic prevalence of use among the elderly in France could be observed, mostly for antipsychotics or benzodiazepines (e.g. antipsychotics, 2006-2013: 10.3% decrease and benzodiazepines 2012-2020: decrease from 30.6% to 24.7% in subjects aged ≥65). Psychotropic prevalence of use remained however very high overall (e.g. antidepressants, 2013: 13% in subjects aged 65-74 and 18% in aged ≥65), exceeding that of most other countries, with a significant proportion of inappropriate use (e.g. in 30% of benzodiazepine users, all ages) carrying a clearly identified risks for uncertain benefit. Initiatives have been multiplied at the national level to reduce psychotropic overuse in the elderly. The reported prevalences demonstrate their effectiveness is obviously insufficient. This limited effectiveness is not specific to psychotropics and might reside in a failure to create strong adherence to messages and recommendations. Other levels should be considered, especially regional, for interventions coupled with pharmacoepidemiologic monitoring allowing impact assessment.

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.