Table 4.

National Annual Estimates of Rate of Adverse Drug Events Treated in U.S. Outpatient Clinics and Emergency Departments by Medication Class, 1995–2005

Medication Class	National Annual Estimate, No.		No. of ADE Visits per 1000 Visits Associated with Medication Therapy (95% CI)
	Imputed Total ADE Visitsa,b	Outpatient Visits Associated with Medication Therapyc
Antimicrobial agents	956,652	145,386,473	6.6 (5.4– 8.0)
Penicillins	124,920	43,217,595	2.9 (2.1– 4.0)
Macrolides	24,557	25,354,784	1.0 (0.5– 1.8)
Tetracyclines	40,637	7,483,149	5.4 (2.1– 14.0)
Cephalosporins	49,028	28,364,606	1.7 (1.0– 2.9)
Sulfonamides	96,611	9,892,418	9.8 (6.4– 14.9)
Quinolones	43,195	13,017,106	3.3 (1.8– 6.1)
Hormones and synthetic substitutes	777,600	113,834,618	6.8 (5.3– 8.8)
Adrenal cortical steroids	134,678	29,287,949	4.6 (2.8– 7.4)
Estrogen and progesterones	157,768	35,648,715	4.4 (3.2– 6.2)
Insulin and hypoglycemic agents	104,488	33,261,795	3.1 (1.9– 5.1)
Cardiovascular agents	736,580	153,932,147	4.8 (3.7– 6.2)
Cardiotonic glycosides	37,704	10,462,496	3.6 (2.3– 5.6)
Antihyperlidipemics	76,121	40,718,906	1.9 (1.1– 3.1)
Antihypertensives	226,013	103,595,779	2.2 (1.5– 3.1)
Diuretics		49,606,844	0.8 (0.5– 1.6)
Central Nervous system agents	630,333	261,529,964	2.4 (1.9– 3.0)
Anticonvulsants	58,387	18,394,383	3.2 (2.0– 5.1)
Anesthetics	18,547	11,929,541	1.6 (0.8– 2.9)
Antidepressants/ mood stabilizers	143,880	57,197,767	2.5 (1.8– 3.6)
Antipsychotics	45,615	10,952,088	4.2 (2.4– 7.2)
Sedatives	57,365	41,696,313	1.4 (0.8– 2.5)
Stimulants	31,122	10,012,500	3.1 (1.8– 5.4)
Analgesics/antipyretics	357,751	168,595,966	2.1 (1.6– 2.8)
Opiates	43,485	39,755,748	1.1 (0.8– 1.5)
Non-opiate-based agents	188,437	141,262,606	1.3 (1.0– 1.9)
Agents affecting primarily skin and mucous membranes	155,321	54,191,037	2.9 (1.9– 4.2)
Antineoplastic and immunosuppressive agents	130,312	10,122,617	12.9 (7.8– 21.0)
Antihistamines, cold remedies, and respiratory agents	109,698	115,336,928	1.0 (0.6– 1.6)
Hematologic agents	95,422	29,248,024	3.3 (2.0– 5.4)
Topical ear, nose, and throat agents	79,400	38,049,667	2.1 (1.3– 3.4)
Vaccines	81,931	33,051,781	2.5 (1.7– 3.6)
Gastrointestinal agents	60,345	61,464,371	1.0 (0.5– 2.1)
Agents affecting primarily muscles	21,698	15,060,353	1.4 (0.8– 2.7)

^aRepresents sum of outpatient clinic and emergency department ADE visits.

^bImputation was performed assuming that the distribution of medication cases was the same among known and unknown cases. The sum of ADE visits for specific medication classes is not necessarily equal to the number of ADE visits for the medication class grouping (indicated in bold), since not all medication classes were included in this table.

^cIncludes all visits to outpatient clinics and emergency departments that list medications as part of the patient’s outpatient therapy.