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Although many adverse drug reactions are not very serious, some cause serious injury, hospitalization and even death. Landmark research published in 1998 in the Journal of the American Medical Association (JAMA) estimated that 2.2 million people who were hospitalized in the U.S. in 1994 had suffered serious adverse drug reactions, of which more than 100,000 were fatal.[1]
The 1998 JAMA study researchers reported that 70 percent of these serious adverse drug reactions preceded the...
Although many adverse drug reactions are not very serious, some cause serious injury, hospitalization and even death. Landmark research published in 1998 in the Journal of the American Medical Association (JAMA) estimated that 2.2 million people who were hospitalized in the U.S. in 1994 had suffered serious adverse drug reactions, of which more than 100,000 were fatal.[1]
The 1998 JAMA study researchers reported that 70 percent of these serious adverse drug reactions preceded the patients’ hospitalizations — and therefore resulted from use of outpatient medications. The researchers, however, did not examine the specific types of drugs that caused these adverse reactions.
An important new study published in JAMA in November 2016 shows that adverse events caused by outpatient drugs are leading more older adults in the U.S. to seek care in emergency rooms (ERs) and to be hospitalized.[2] The study also identified the outpatient medications that are most likely to prompt trips to the ER.
Table 1: Adverse Drug Events Seen For the Top Four Drug Classes Implicated in U.S. Emergency Room Visits in 2013-2014
| Drug Class | Most Common Types of Adverse Events |
|---|---|
| Anticoagulants | Bleeding involving the gastrointestinal tract (for example, stomach or colon), skin or wounds, nose, urinary tract (for example, kidney or bladder) or brain; blood tests indicating excessive anticoagulation or overdosing |
| Antibiotics | Allergic reactions, gastrointestinal effects (for example, nausea, vomiting or diarrhea) |
| Diabetes drugs | Hypoglycemia (low blood sugar) with the following: mental status changes, shock, loss of consciousness, seizures, falls, other injuries, dizziness, or fainting |
| Opioid analgesics | Mental status changes, loss of consciousness, breathing problems, dizziness, fainting, weakness, difficulty walking, gastrointestinal symptoms, difficult urinating, allergic reactions |
Study overview
In 2004, the Centers for Disease Control and Prevention (CDC), the Consumer Product Safety Commission and the Food and Drug Administration launched a national surveillance system to track outpatient adverse drug events that result in hospital ER visits.[3] The system collects data from a nationally representative sample of U.S. hospitals that have a minimum of six beds and a 24-hour ER.[4] The data collected can be used to estimate the total number of such events occurring throughout the U.S.
For each ER visit involving any diagnosed adverse drug event at one of the participating hospitals, information is recorded regarding the patient’s age and sex, clinical details about the adverse event, the drugs that the patient was taking and whether the patient was sent home or admitted to the hospital. Cases include ER visits for adverse events linked to prescription or over-the-counter medications, dietary supplements, homeopathic products or vaccines.
The adverse drug events are classified into the following six types: 1) adverse effects (for example, vomiting or bleeding), 2) allergic reactions, 3) excessive drug effect or overdose, 4) secondary effects (for example, choking), 5) accidental ingestion by a child or 6) vaccination reaction.
The 2016 JAMA study, which was led by a team of CDC researchers, describes the characteristics of ER visits for adverse drug events for 2013-2014 and the changes in such events since 2005-2006.
Key findings
The researchers estimated that there were four ER visits for adverse drug events per 1,000 people annually in 2013-2014. Based on our calculations, this translates into more than 1.2 million such visits per year in the U.S. The annual rate of these ER visits has gradually increased since 2005- 2006, when it was 2.6 visits per 1,000 people, which translated into approximately 768,000 visits per year.
Not surprisingly, ER visits for adverse drug events occur most frequently in older adults (those aged 65 or older). In 2013-2014, approximately 35 percent of all such visits involved older adults. Particularly troubling is the dramatic rise in the rate of ER visits for adverse drug events in older adults in recent years: In 2005-2006, there were 5.2 visits per 1,000 older adults annually, and by 2013-2014, the rate had risen to 9.7, an increase of more than 80 percent. Among adults aged 50 to 64, the rate increased from 2.5 visits per 1,000 in 2005-2006 to 4.3 per 1,000 in 2013- 2014, a 72 percent increase. Smaller increases were seen in the rates for younger age groups.
A single medication was implicated in 84 percent of ER visits for adverse drug events in 2013-2014, whereas two or more drugs played a role in the remaining visits. The three most common types of adverse drug events were excessive drug effect or dose (37 percent), adverse effect (28 percent) and allergic reaction (26 percent).
Table 2: Top 15 Drugs Implicated in Emergency Room Visits for Adverse Drug Events in Adults Aged 65 or Older in 2013-2014
| Generic Drug Names | Selected Brand Names | Drug Class | Proportion of Cases |
|---|---|---|---|
| warfarin | COUMADIN, JANTOVEN | Anticoagulant | 32% |
| insulin | HUMALOG, HUMULIN, LANTUS, LEVEMIR, NOVOLIN, NOVOLOG | Diabetes drug | 13% |
| clopidogrel* | PLAVIX | Antiplatelet drug | 10% |
| aspirin | DURLAZA | Antiplatelet drug/non-steroidal anti-inflammatory drug (NSAID) | 7% |
| rivaroxaban** | XARELTO | Anticoagulant | 3% |
| lisinopril* | PRINIVIL, ZESTRIL | Angiotensin-converting enzyme inhibitor, high blood pressure drug | 3% |
| metformin* | FORTAMET, GLUCOPHAGE | Diabetes drug | 3% |
| glipizide* | GLUCOTROL | Diabetes drug | 2% |
| sulfamethoxazole-trimethoprim | BACTRIM, SEPTRA | Antibiotic | 1% |
| dabigatran** | PRADAXA | Anticoagulant | 1% |
| acetaminophen-hydrocodone | ANEXSIA, NORCO | Opioid analgesic | 1% |
| metoprolol | LOPRESSOR, TOPROL-XL | Beta blocker, high blood pressure drug | 1% |
| enoxaparin | LOVENOX | Anticoagulant | 1% |
| glyburide* | DIABETA, GLYNASE | Diabetes drug | 1% |
| glimepiride* | AMARYL | Diabetes drug | 1% |
*Classified as Limited Use by Public Citizen’s Health Research Group.
**Classified as Do Not Use for Seven Years by Public Citizen’s Health Research Group (until July 2018 for rivaroxaban and November 2017 for dabigatran).
Slightly more than a quarter of all ER visits for adverse drugs events in 2013-2014 resulted in hospitalization. The proportion of older adults who were hospitalized after such ER visits was 44 percent, the highest of any age group. Moreover, the hospitalization rate for adverse drug events among adults aged 65 or older was seven times greater than the rate for people younger than 65 (4.2 versus 0.6 hospitalizations per 1,000 people per year, respectively).
The JAMA study has likely underestimated the number of outpatient adverse drug events for several reasons. First, the study did not include patients with adverse drug events who were treated in — or directly admitted to the hospital from — non-ER settings, such as physician offices. Second, ER physicians — like many health care professionals — often fail to identify adverse drug reactions, particularly those that are less severe. Third, fatal adverse drug events are not captured by the national surveillance system used by the study team. Finally, the data excluded ER visits related to intentional abuse of medications.
Most commonly implicated drugs
According to the JAMA study, the four classes of drugs that were most commonly implicated in ER visits for adverse drug events in 2013-2014 and the estimated proportion of each across all age groups were:
- anticoagulants (blood thinners), 18 percent
- antibiotics, 16 percent
- diabetes drugs, 13 percent
- opioid analgesics (pain relievers), 7 percent
These same four drug classes also were the most common drug classes implicated in ER visits for adverse drug events a decade earlier. Table 1 (see page 3) provides examples of the most common types of adverse drug events seen in ER patients for each of these drug classes.
The most common classes of drugs implicated in ER visits for adverse drug events varied by age. Among children and adolescents (individuals aged 19 or younger), antibiotics were by far the most commonly implicated drugs, whereas for older adults, anticoagulants and diabetes drugs were implicated most frequently.
Table 2 (above) lists the top 15 individual drugs implicated in ER visits for adverse drug events in older adults. The top drug, warfarin (COUMADIN, JANTOVEN), was implicated in 32 percent of these visits.
What You Can Do
To minimize your chances of ending up in the ER due to an adverse drug event, follow our 10 rules for safer drug use, which were last published in the March 2015 issue of Worst Pills, Best Pills News. These rules are also available for free online at www.worstpills.org.
References
[1] Lazarou J, Pomeranz BH, Corey PN. Incidence of adverse drug reactions in hospitalized patients: A meta-analysis of prospective studies. JAMA. 1998;279(15):1200-1205.
[2] Shehab N, Lovegrove MC, Geller AI, et al. US emergency department visits for outpatient adverse drug events, 2013-2014. JAMA. 2016;316(20):2115-2125.
[3] Budnitz DS, Pollock DA, Weidenbach KN, et al. National surveillance of emergency department visits for outpatient adverse drug events. JAMA. 2006;296(15):1858-1866.
[4] Shehab N, Lovegrove MC, Geller AI, et al. US emergency department visits for outpatient adverse drug events, 2013-2014. JAMA. 2016;316(20):2115-2125.
