Modelling the time to onset of adverse reactions with parametric survival distributions: a potential approach to signal detection and evaluation.

BACKGROUND: It has been postulated that the time to onset of adverse drug reactions is connected to the underlying pharmacological (or toxic) mechanism of adverse drug reactions whether the reaction is time dependent or not. OBJECTIVE: We have conducted a preliminary study using the parametric modelling of the time to onset of adverse reactions as an approach to signal detection on spontaneous reporting system databases. METHODS: We performed a parametric modelling of the reported time to onset of adverse drug reactions for which the underlying toxic mechanism is characterized. For the purpose of our study, we have used the reported liver injuries associated with bosentan, and the infections associated with the use of the tumour necrosis factor (TNF) inhibitors, adalimumab, etanercept and infliximab, which are used in Crohn's disease and rheumatoid arthritis, reported to EudraVigilance between December 2001 and September 2006. RESULTS: The main results reflect the fact that the reported time to onset is a surrogate of the true time to onset of the reaction and combines three hazards (occurrence, diagnosis and reporting) that cannot be disentangled. Consequently, the modelling of the time to onset of reactions reported with TNF inhibitors showed differences that could reflect different pharmacological activities, indications, monitoring of the patients or different reporting patterns. These variations could also limit the interpretation of the parametric modelling. CONCLUSIONS: Some consistency that was found between the occurrences of the infections with the TNF inhibitors suggests a causal association. There are statistical issues that are important to keep in mind when interpreting the results (the impact of the data quality on the fit of the distributions and the absence of a test of hypothesis linked to the absence of a relevant comparator). The study suggests that the modelling of the reported time to onset of adverse reactions could be a useful adjunct to other signal detection methods.

Pharmacovigilance-related topics at the level of the International Conference on Harmonisation (ICH).

Marketing authorisations for medicines need to be based on the universal criteria quality, safety and efficacy, whilst taking into account local public health needs. With view to using resources efficiently and avoiding delay in access to medicines, scientific standards for investigating quality, safety and efficacy should be universal too. A major step to achieve this was taken in 1990 when the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) was established between authorities and industry in the European Union (EU), Japan and the United States. Since then more than 50 ICH Guidelines have been published, out of which six are specific to pharmacovigilance. They refer to management and expedited reporting of individual adverse drug reaction (ADR) cases, including electronic formats, periodic reporting of worldwide data and planning of pharmacovigilance. Their development has to be seen in the context of initiatives taken in the three ICH Regions to strengthen pharmacovigilance. Most recently this involves making use of risk management concepts, reflecting new thinking of proactivity in pharmacovigilance. Moreover, consideration is given to regional and international cooperation beyond the ICH Regions.

CIOMS and ICH initiatives in pharmacovigilance and risk management: overview and implications.

In this article we review the current initiatives by the Council for International Organizations of Medical Sciences (CIOMS) and the International Conference on Harmonisation (ICH) on pharmacovigilance planning that are due for general release during 2004. These initiatives could form the basis for applying concepts of risk management to medicines throughout their life cycle, from preclinical and clinical development to marketed use. The CIOMS VI Working Group (with 28 senior scientists worldwide from drug regulatory authorities and pharmaceutical companies) is currently developing scientific guidance that relates to clinical trials for medicines during development. It recommends a developmental pharmacovigilance concept - a 'living' concept that would start early in drug development supporting the science and ethics of research leading up to licensing (marketing authorisation) and continuing to post-authorisation (postmarketing) pharmacovigilance. This approach is seen as complementary to current ICH initiatives called 'Pharmacovigilance Planning'. ICH will introduce two concepts in pharmacovigilance management of medicinal products: the 'Pharmacovigilance Specification' and the 'Pharmacovigilance Plan'. The 'Pharmacovigilance Specification' will summarise important knowns and unknowns about the medicine. It will include safety risks identified at the licensing stage, potential risks and any key missing information. These elements will be essential to the formulation of pharmacovigilance plans. Dialogue and common understanding between regulators and the pharmaceutical industry will be a key factor for developing pharmacovigilance plans during the life cycle of medicines. Appropriate interaction with health professionals and patients should also be planned for the future as regulatory systems become more transparent. Where no significant issues are apparent at the licensing (marketing authorisation) stage, routine pharmacovigilance practices will be followed during the marketing phase. Where issues do exist or the data are limited, further study, including epidemiological approaches can be planned. All types of medicines (new drugs, biological agents, orphan drugs) may be involved in these concepts, as would major extensions to existing medicines. Currently ongoing CIOMS and ICH initiatives are in line with emerging risk-management strategies in the US, the European Union and Japan aimed at early and proactive pharmacovigilance.