Single-case causality assessment

It is an important duty of safety monitors working for a sponsor to make some sort of assessment of causal relationship between ADEs and treatment. Often a preliminary assessment has been made by the reporting physician. In the past such assessment was made by skilled judgement on the part of the physician and/or monitor. There has been some interesting work on applying Bayesian quantitative methods in order to provide numerical assessments of the probability that an ADE is really an ADR (Cowell et ah, 1993 Hutchinson et al., 1991a,b). Such single-case causality assessment is, in fact. 

The 1994 report of the Institute of Medicine concluded that the evidence was inadequate to accept or reject a causal relation between MMR and encephalopathy, and it is known that the incidence of encephalitis after measles immunization of healthy children tends to be lower than the observed incidence of encephalitis of unknown cause. Two large studies have been negative. In a study analogous to the British Childhood Encephalopathy Study there were no increased risks of either encephalopathy or neurological sequelae after measles immunization (19). A retrospective case-control study through the CDC Vaccine Safety DataUnk assessing the risk for 300 000 doses of MMR found not a single case of encephalitis/ encephalopathy within 30 days of the administration of MMR (20). In contrast, the review mentioned above (18) reported an association between measles vaccine and encephalopathy. However, the conclusion of the report of the Institute of Medicine is still valid, namely that evidence is stiU inadequate to accept or reject a causal relation between measles vaccine and these diseases. 

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