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Medication Errors in Adults-Case #10: Nonadherence


A greater focus on potential barriers may help prevent errors, increased costs, and poor patient outcomes.

Medication errors may occur at any point in the health care system. Obtaining a true estimate of the number of errors is difficult, but preventable medication errors are known to increase patient harm and total health care costs.1

This series highlights some of the most important drug errors and addresses methods to decrease the risk of them occurring. In the first article, I addressed a common error associated with warfarin.2 The second article focused on a common error that involved acetaminophen and duplicate therapy.3 In the third article, I addressed a common error associated with duplicate therapy.4 The fourth article discussed a common error with chemotherapy drug interactions.5 In the fifth article, I looked at potential errors related to pharmacotherapy in patients with renal insufficiency.6 The sixth article described errors associated with insulin.7 In the seventh article, I addressed errors associated with pregnancy.8 The eighth case described errors associated with medication use in geriatric patients.9 The ninth case took us back to the basics of medication errors and reviewed potential errors resulting from look-alike/sound-alike medications as well as errors associated with abbreviations.10 In the current case, I look at potential medication errors resulting from medication nonadherence.

Case #10: Nonadherence

A 58-year-old woman with a past medical history of hypertension, chronic obstructive pulmonary disease, type 2 diabetes mellitus (T2DM), hypercholesterolemia, and depression presents to the clinic 3 months after beginning treatment for hypertension. Current medications include atorvastatin, 80 mg/d; ezetimibe, 10 mg/d; aspirin, 81 mg/d; metformin, 1000 mg twice daily; tiotropium bromide capsules, 1 inhalation daily; ADVAIR DISKUS (fluticasone/salmeterol) 250 µg/50 µg, twice daily; albuterol MDI, 2 inhalations prn; lisinopril, 20 mg/d; and hydrochlorothiazide (HCTZ), 12.5 mg/d.

At this visit, the patient’s blood pressure is uncontrolled at 152/96 mm Hg (average of 2 readings; JNC 8 goal, lower than 140/90 mm Hg) and the HCTZ dosage is increased to 25 mg/d. Three months later, the patient returns and her blood pressure is still slightly elevated at 145/94 mm Hg (average of 2 readings). She states she has missed a few doses of medications, including lisinopril and atorvastatin. Therefore, her medications are continued at the current dosages and she is reminded to take all medications. Six months later, she is seen in the ED with a hypertensive emergency and is hospitalized.

What is the problem in this scenario?


A medication error is defined as “any preventable event (action or omission) that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care professional, patient, or consumer.”11 When medication errors are evaluated or discussed, the focus often remains on the health care provider or the health care system. However, the patient is an important part of the process.

Therefore, nonadherence to medications, defined as “the extent to which a person’s behavior-taking medication, following a diet, and/or executing lifestyle changes-corresponds with agreed recommendations from a health care provider,”12 also could represent a medication error related to administration of medications. This inappropriate use or omission of medications by a patient ultimately may lead to harm and increased costs to the patient and the health care system. In fact, nonadherence may add an estimated $290 billion in costs to the US health care system annually.13

In the case above, the patient has been hospitalized because of a hypertensive emergency. Nonadherence to hypertension medications is a common cause of hypertensive crises,14 and it may be the cause in this case, especially given the patient’s history of nonadherence.

Patients who are taking medication for chronic diseases, including hypertension, often become nonadherent. An estimated 50% of patients are nonadherent 1 year after the initial prescription was written, in addition to up to one-third of patients who never initially fill the prescription and up to 50% of patients who may not be adherent with the directions and do not take the medication as prescribed.15-17

There are many barriers to adherence to medications, and many are evident in the case above. All practitioners need to understand and be able to identify these barriers to facilitate good medication-taking behaviors. Barriers may include patient-related factors, such as socioeconomic status, medication cost, and forgetfulness, and lifestyle factors, such as alcohol use and depression.

The patient in the above case is being treated for a diagnosis of depression, which can contribute to nonadherence if the patient is not fully treated. In addition, the patient may be forgetful; the addition of a pill box may serve as a reminder and help remedy this unintentional nonadherence.

Other barriers to adherence include medication-related factors, such as frequency of dosing; pill burden or polypharmacy; and adverse drug reactions (ADRs). In the case above, the patient could have an ace inhibitor–induced cough that prevents her from taking her meds, specifically the lisinopril for hypertension. Switching this medication for another hypertension medication may result in improved blood pressure control.

The overall number of medications also may contribute. Potential solutions to this problem may include combination medications, such as lisinopril/HCTZ, which would reduce the overall number of pills the patient has to take per day, and medication review to remove medications that have no clear indication.

Perhaps more important are patients’ experiences, perceptions, and understanding of their disease states and medications because they can contribute directly to intentional nonadherence. These health literacy issues can cause a patient to choose not to take his or her medication; in the case above, the patient may feel better, having no symptoms of hypertension, and therefore stop taking the hypertension medication. Patients may not fully understand the consequences of undertreated hypertension or the goals of their treatment, leading them to discontinue medications. Patients who have multiple comorbidities, such as the one in this case, also may be more at risk for nonadherence and need even more extensive education and time devoted to their care.

Health system– or prescriber-related factors may contribute to this type of barrier. Time constraints placed on clinicians can affect the amount of time spent educating and counseling patients on the disease state and complications, medications, and treatment goals. A multidisciplinary approach to patient education may help prevent nonadherence related to these types of barriers and increase the amount of time available to each patient’s care.

Patients such as the one in this case could easily continue to receive prescriptions for more hypertension medications as an attempt to control their blood pressure. This most likely would have no further effect on blood pressure control, because of nonadherence, and could negatively impact adherence even further as well as lead to further ADRs or medication-related problems.


Interventions that target nonadherence, the root of the problem, may have the greatest impact on the patient’s blood pressure and outcomes. These interventions should be multidisciplinary and focus on the patient-specific barriers that are present. In addition, further focus within the health care system on identification of medication nonadherence, as well as potential barriers, may help prevent errors, increased costs, and poor patient outcomes.


1. Institute of Medicine. To Err Is Human: Building a Safer Health System. Washington, DC: National Academy Press; 1999.

2. Medication errors in adults-Case #1: warfarin. July 29, 2013.

3. Medication errors in adults-Case #2: acetaminophen. August 21, 2013.

4. Medication errors in adults-Case #3: duplicate therapy. September 24, 2013.

5. Medication Errors in Adults-Case #4: chemotherapy drug interactions. October 25, 2013.

6. Medication Errors in Adults-Case #5: renal insufficiency. November 25, 2013.

7. Medication Errors in Adults – Case #6: Insulin. December 17, 2013.

8. Medication Errors in Adults – Case #7: Pregnancy. January 21, 2014.

9. Medication Errors in Adults – Case #8: Geriatrics. February 19, 2014.

10. Medication Errors in Adults – Case #9: Traditional Errors. March 18, 2014.

11. National Coordinating Council for Medication Error Reporting and Prevention. About Medication Errors. http://www.nccmerp.org/aboutMedErrors.html. Accessed April 16, 2014.

12. World Health Organization. Adherence to Long-Term Therapies: Evidence for Action. http://whqlibdoc.who.int/publications/2003/9241545992.pdf. Accessed April 16, 2014.

13. Network for Excellence in Health Innovation. Thinking Outside the Pillbox: A System-wide Approach to Improving Patient Adherence for Chronic Disease. http://www.nehi.net/publications/17-thinking-outside-the-pillbox-a-system-wide-approach-to-improving-patient-medication-adherence-for-chronic-disease/view. Accessed April 16, 2014.

14. Shea S, Misra D, Ehrlich MH, et al. Predisposing factors for severe, uncontrolled hypertension in an inner-city minority population. N Engl J Med. 1992;327:776-781.

15. Peterson AM, Takiya L, Finley R. Meta-analysis of trials of interventions to improve medication adherence. Am J Health Syst Pharm. 2003;60:657-665.

16. Haynes RB, Ackloo E, Sahota N, et al. Interventions for enhancing medication adherence. Cochrane Database Syst Rev. 2008:CD000011.

17. Osterberg L, Blaschke T. Adherence to medication. N Engl J Med. 2005;353:487-497.

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