Adverse drug reactions and therapeutic errors in older adults: a hazard factor analysis of poison center data.

Purpose: The severity of hazards posed by medications implicated in poisoning in older adults was characterized.
Methods: Toxic Exposure Surveillance System (TESS) cases from 1993 through 2002 involving a single substance in patients age 60 years or older and coded as an adverse drug reaction (ADR) or therapeutic error were analyzed. Hazard factors were determined for each exposure reason by calculating the sum of the major effects and deaths for each substance category and subcategory and dividing this by the total number of exposures for the respective category or subcategory.
Results: Hazard factors were calculated for 12,737 ADRs and 51,846 therapeutic errors. The overall rates of major effects and deaths were 7.5% and 1.6% in the ADR and therapeutic error groups, respectively. In the ADR group, five TESS categories had a hazard factor of > or =2.0: anesthetics, anticoagulants, antineoplastics, cardiovascular drugs, and radiopharmaceuticals. In the therapeutic error group, five drug categories also had a hazard factor of > or =2.0: anesthetics, anticoagulants, antineoplastics, asthma therapies, and serums/toxoids/vaccines. Six pharmaceutical categories were associated with hazard factors of > or =2.0 in both the ADR and therapeutic error groups.
Conclusion: An analysis of ADRs and therapeutic errors involving older adults and reported to poison control centers from 1993 through 2002 revealed overall rates of major effects and death of 7.5% and 1.6% in the ADR and therapeutic error groups, respectively. Antineoplastics, aminophylline or theophylline, cardiac glycosides, heparin, morphine, and warfarin were implicated in more than 50 cases and associated with hazard factors of > or =2.0 for both exposure groups.