Very many signals are produced, and our ability to analyse them is limited. Currently, there seems to be little consistency over what signals will be considered further. Serious signals that appear to be new, and relate to new drugs, usually elicit regulatory action. Less serious signals that may none the less have an important impact on morbidity and compliance may not be investigated so rigorously even when the numbers build up. Epidemiological studies may take months to years to perform during which time thousands of patients may be exposed to the signalled risk.
This period of new signal analysis is rarely made transparent, and controversies tend to linger. Almost the whole effort of this vast collection machinery for clinical case report information is directed towards finding new ADR signals. Little use is made of the data for other signal work, such as:
* finding at-risk groups (e.g. do some ADRs occur disproportionately with age?)
* interactions (do known reactions occur more frequently with certain medicine combinations?)
* ADRs related to usage (e.g. do certain reactions occur more frequently in certain countries? at higher doses?)
This is not surprising, since the quantity of data is so large and most national centers have few resources. Several needs are apparent if we are to meet the challenges of the future. Amongst the most important are:
* to encourage clinicians to report clinically relevant experience
* to give advice about the diagnosis and management of ADRs
* to improve the rapid transmission of quality information to national centres and industry, and thence to the WHO database
* to find ways of supporting the examination of large amounts of disparate information
* to be able to bridge the gap between a tentative signal from raw ADR data and observational studies that use specific protocols.
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