Epidemiology of hypersensitivity drug reactions

Hypersensitivity drug reactions are but one of the many different types of adverse drug reactions. They may be potentially life-threatening, prolong hospitalization, affect drug prescribing patterns of physicians and result in socioeconomic costs. This review summarizes current knowledge on the incidence, prevalence, mortality and risk factors for these reactions in different populations.

Hypersensitivity reactions represent about one third of all adverse drug reactions. Adverse drug reactions affect 10-20% of hospitalized patients and more than 7% of the general population. Severe reactions including anaphylaxis, drug hypersensitivity syndromes, Stevens Johnson syndrome and toxic epidermal necrolysis are also associated with significant morbidity and mortality. Although several risk factors have been identified, their clinical importance has not been fully understood. Future progress in immunogenetics and pharmacogenetics may help identify populations at risk for specific types of reactions.

Well designed epidemiological studies on hypersensitivity drug reactions are lacking as most studies have been on adverse drug reactions. Such studies will be helpful in identifying patients at risk of developing such reactions, in particular severe reactions, and implementing early preventive measures.