Adverse event relationship between serious

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. 

Establishing a cause-effect relationship between an adverse event and the use of a drug is a serious and difficult problem. Karch and Lasagna proposed degrees of certainty for attributing an adverse event to a drug, as shown in Box 6.7. 

The relationship between vitamins C and E supplementation and the markers of haemolysis in sickle cell anaemia has been evaluated in a six-month randomised, double-blind, placebo-controlled trial including 83 patients [29 ]. The most commonly reported adverse events in the vitamins versus placebo group were headache (18% vs 10%), nausea (14% vs 10%), fatigue (11% vs 13%), diarrhoea (7% vs 0%), and epigastric pain (5% vs 1%). All serious adverse events were sickle cell anaemia-related. 

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