Incidence of fatal adverse drug reactions: a population based study

Abstract

What is already known about this subject: * Although drugs generally are safe and effective therapies for numerous diseases, adverse drug reactions do occur and may even be fatal. * The incidence of fatal adverse drug reactions in hospitalized patients has been estimated to be approximately 5%. * In previous studies the incidence of fatal adverse drug reactions in hospitalized patients has been reported, but the incidence of fatal adverse drug reactions in the general population is largely unknown.

What this study adds: * Fatal adverse drug reactions account for approximately 3% of all deaths in the general population. * Haemorrhages amount to almost two-thirds of the fatal adverse drug reactions and antithrombotic agents are implicated in more than half of the suspected fatal adverse drug reactions. * Fatal adverse drug reactions are estimated to be the seventh most common cause of death in Sweden.

Aims: To determine the incidence of fatal adverse drug reactions (FADRs) in a Swedish population.

Methods: Every seventh randomly selected deceased in three counties in South-east Sweden during 1 January 2001-31 December 2001 was identified in the Cause of Death Register. Relevant case records (hospitals and/or primary care centres and medicolegal files) were reviewed to identify suspected drug-related fatalities.

Results: Of 1574 deceased study subjects, 49 (3.1%; 95% CI 2.2%, 4.0%) were suspected to have died from FADRs. The most common suspected FADRs were gastrointestinal haemorrhages (n = 18; 37%), central nervous system haemorrhages (n = 14; 29%), cardiovascular disorders (n = 5; 10%), other haemorrhages (n = 4; 8%) and renal dysfunction (n = 3; 6%). The drugs most commonly implicated in FADRs were antithrombotic drugs (n = 31; 63%), followed by nonsteroidal anti-inflammatory drugs (NSAIDs) (n = 9; 18%), antidepressants (n = 7; 14%) and cardiovascular drugs (n = 4; 8%). Of all the 639 fatalities in hospital 41 (6.4%; 95% CI 4.5%, 8.3%) were suspected to be due to FADRs.

Conclusions: The medical burden of FADRs is significant. Haemorrhages were seen in a majority of the FADRs; antithrombotic agents or NSAIDs were implicated in most of these events. These results suggest that preventive measures should be taken to reduce the number of deaths caused by drugs.