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Principles of Signal Detection
Pia Caduff-Janosa MD
Annual Course May 2013
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Outline
• What is a signal?
• Signal sources
• Triggers
• Assessment of potential risk
• Signal evaluation
• Outcome
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What is a signal?
• Reported information on a possible causal relationship between an adverse event and a drug, the relationship being unknown or incompletely documented previously.
• Usually more than a single report is required to generate a signal, depending upon the seriousness of the event and the quality of the information. The publication of a signal usually implies the need for some kind of review or action.
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Signal sources
• Individual Case Safety Reports
• Clinical studies
• Literature
• WHO Programme-UMC
• Scientific conferences
• Drug Regulatory Authorities
• Media
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Signal bells... .... when should they start ringing?
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Triggers
• ADR reported is unexpected
• Fatal outcome or life threatening course
• Specific ADRs – SJS, TEN
– Agranulocytosis
• Cluster
• Unusual aspects of expected ADRs
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Individual case safety report
Signal confirmed?
Action
Case series further information
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How many reports make a signal?
• 3 index cases – Completely documented
– No or only minimal confounders
– Positive de-/rechallenge
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”Further information”?
• What do we know about the drug itself?
• What do we know about the way it is used?
• What do we know about similar drugs (class effects)?
• Is there a reasonable causal relationship between drug and reaction in our case reports?
• Signal assessment = causality assessment??
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Signal assessment
• Labelling – national and international
• Case series in databases? – National database
– VigiBase/VigiLyze
• Literature
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Signal assessment
• ”Small” database – Mostly case series and assessment of ICSRs
• Large database – Automated search for disproportionalities
– Case series
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UMC signalling process
Data mining Disproportionality
measure (IC)
Clinical assessment
UMC + Review Panel
National PV Centres Pharma Company
Not (yet) signal
Triage algorithms
UMC review Literature check etc
WHO db VigiBase
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Data analysis – single case
• Demographic data • Medical history • Chronology • Risk factors • Differential diagnosis • De-/Rechallenge • Concomitant medication • Other confounders/bias
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Signal assessment is about patterns
• Who is at risk?
• Are there patient specific risk factors?
• Are there drug specific risk factors?
• Is there a geographical pattern?
• Does the ADR follow a pattern?
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Signal assessment
• There is no magic button...
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Signal assessment is about...
• Hard and patient intellectual work
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...and
• Decision making
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Dilemma
• A signal should be identified as soon as possible to allow early warning
but
• should be documented as well as possible (credibility) → When is there ENOUGH evidence?
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Risk minimization
• Action taken (mostly) by Regulatory Authorities with the aim of keeping a positive benefit risk balance
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Potential risk
• Exposed population (size, sensitive populations)
• Essential medicinal product
• Seriousness and severity of ADR
• Avoidable ADR?
• Rapid increase of number of reports
• Public impact and perception
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The risk potential defines the next move
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• If the risk is assessed as very high, risk minimizing actions might be justified even if the signal is not (yet) confirmed
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• ...on Monday May 27th @ 8.30 am
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Take home messages
• A signal is a work hypothesis that needs to be confirmed or refuted
• Signal assessment is a dynamic process • Signal detection is a lifelong process for
every medicinal product • Well documented ICSRs (index cases) are
one of the most precious elements in signal detection and assessment
• Signal assessment is intellectual work
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Questions?
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Uppsala Monitoring CentreBox 1051SE-751 40 Uppsala, SwedenVisiting address: Bredgränd 7, Uppsala
tel +46 18 65 60 60fax +46 18 65 60 88website www.who-umc.org