Reports of suspected adverse drug reactions (ADRs) are collected by the Medicines and Healthcare products Regulatory Agency (MHRA) and Commission for Human Medicines (CHM) through the spontaneous reporting scheme, the Yellow Card scheme. Approximately 19,000 reports of suspected ADRs are sent to the MHRA/CHM through this scheme each year. It is not possible to estimate from the Yellow Card scheme the number of people who suffer adverse drug reactions with a fatal outcome since the scheme is associated with an unknown level of under-reporting.
Table 1 shows the total number of suspected adverse drug reaction (ADR) reports received via the Yellow Card scheme in the United Kingdom in each of the past seven years, and the number associated with a fatal outcome.
Total number of adverse drug reaction reports Number of adverse drug reaction reports with a fatal outcome 1999 20,347 782 2000 35,981 846 2001 23,680 893 2002 19,748 881 2003 21,637 986 2004 22,986 1,168 2005 25,261 1,424
It is important to note that a report of an adverse drug reaction does not necessarily mean that it was caused by the drug. Many factors have to be taken into account in assessing causal relationships including temporal association, the possible contribution of concomitant medication and the underlying disease being treated.
A study funded by the MHRA and published in the British Medical Journal on 2 July 2004, was conducted in two large hospitals in Merseyside in order to ascertain the current burden of ADRs in the NHS. The study found that of 18,820 patients aged over 16 years admitted to hospital over a six month period, there were 1,225 admissions judged to be related to an ADR, giving a prevalence of 6.5 per cent. Of these 1,225, the ADR was judged to lead directly to the admission in 80 per cent. of cases. Adverse drug reactions were considered responsible for the death of 0.15 per cent. of all the patients admitted.