ABSTRACT
Adverse drug reactions (ADRs) represent a major public health problem. A meta-analysis
by Lazarou et al. (1), based mainly on studies conducted before 1990, showed that 6.7% of
hospitalized patients developed serious ADRs, while 0.32% had a fatal ADR. Extrapol-
ation of the fatality rate to the population of the United States suggested that ADRs
killed more than 100,000 patients in the United States in 1994, making them between
the fourth and sixth leading cause of death. In one of the largest prospective studies
ever conducted, we have shown that even with present-day therapeutics, ADRs are respon-
sible for 6.5% of all hospital admissions, accounting for 4% of the National Health Service
(NHS) hospital bed occupancy at an annual cost approaching £0.5 billion (2). In children,
the overall incidence of ADRs may be as high as 9.5% (3) although larger prospective
studies are desperately needed in this area. The overall cost of drug-related morbidity and
mortality in the United States (taking into account both primary and secondary care) has
been estimated to be more than $76 billion (4). There are also cost implications for the
pharmaceutical industry: the cost of bringing a drug to the market has been estimated to
be up to $800 million (5). It has been estimated that up to 4% of the drugs marketed in
the United Kingdom over a 20-year period were withdrawn because of safety issues (6).
