The answer to the title question is, "It’s complicated" — because for most patients, there is not one unique and distinct reason for nonadherence, nor is there one simple solution for correcting it.
The complexity of this issue was detailed last year in a New York Times health blog post by Danielle Ofri, MD. Dr. Ofri, a New York City internist with a PhD in pharmacology, recounted what it would take for a 67-year-old patient who has diabetes, hypertension, and high cholesterol to be entirely adherent to all medical recommendations.
"Besides obtaining five prescriptions and getting to the pharmacy to fill them (and that’s assuming no hassles with the insurance company, and that the patient actually has insurance), the patient, would also be expected," wrote Dr. Ofri, "to cut down on salt and fat at each meal, exercise three or four times a week, make it to doctor appointments, get blood tests before each appointment, check blood sugar, get flu shots—on top of remembering to take the morning and evening pills each day. Added up, that’s more than 3,000 behaviors to attend to each year to be truly adherent."
As Dr. Ofri discovered, nonadherence can take many forms. In primary nonadherence, a patient is prescribed a new medication but does not fill the prescription. For example, since only 75 percent of patients with heart failure actually fill their first prescription, we could say 25 percent show primary nonadherence.
Secondary nonadherence occurs when the patient fills the prescription but does not take the medication as prescribed. Secondary nonadherence includes inconsistency in refilling prescriptions, not taking medications as directed, or not taking the medication altogether. Most studies focus on secondary nonadherence, as pharmacy databases can monitor refills over time and primary nonadherence is more difficult to track.
Complicating the situation, reasons for primary nonadherence (e.g., poor access to pharmacy, unaffordability) may be different from those for secondary nonadherence (e.g., lack of belief in a medication’s efficacy), and may therefore require different interventions.
Optimizing adherence often requires prying apart a constellation of barriers to adherence to try to find a root cause. Although it is beyond our scope to dig into all of them, we can explore some that have been identified as particularly formidable.
Often, when patients are asked, they say that they simply forget to take their medications, or admit to being not careful about following directions. Accepting this explanation at face value, a physician might think that an audio alarm or other reminder system should rectify the problem. However, there is evidence that unintentional nonadherence is not, in fact, random. In a survey of more than 24,000 adults with asthma, high blood pressure, diabetes, high cholesterol, osteoporosis, or depression, 70 percent said that in the preceding six months they had forgotten to take medication, had run out of medication, or had been careless about taking the medication.
The high level of nonadherence among this group may be explained by regimen complexity. Many studies have shown an inverse relationship between good adherence and a complicated medication regimen. Complexity includes such factors as the number of drugs prescribed, the types of medications, dosing frequency and timing, method of administration (e.g., injections vs. inhalers), and frequent changes in regimen. Having multiple providers prescribing medications also contributes to nonadherence, as does the need to make frequent trips to the pharmacy. Being asked to prepare the medications oneself, such as by pill splitting or diluting a solution, also presents difficulty for some patients.
One of the strongest obstacles to adherence is high medication cost. For example: Doubling medication co-payments led to a 45 percent drop in the use of NSAIDs and a 26 percent decline in the use of blood pressure medicines and antidepressants. Another study uncovered a fourfold increase in drug discontinuation when out-of-pocket costs for oral cancer therapy surpassed the $500 mark per prescription fill. Unsurprisingly, shared costs are more likely to affect patients taking costlier, branded medications than those who use lower-cost generics.
Various barriers to access can also make it difficult for patients to access their medications. Patients in poor health may literally not be able to travel to a pharmacy on a regular basis and may not reside in areas where pharmacy delivery is available. For this group, mail order services can be helpful. Some hospitals, including Maimonides Medical Center and the Hospital of the University of Pennsylvania, offer to have prescriptions filled by the hospital pharmacy before a patient is discharged. A pharmacist goes to the patient’s bedside to deliver medications and educate the patient about them.
Drug shortages may also prevent patients from obtaining needed medications. A number of vital medicines used in the treatment of cancer, infection, cardiovascular disease, pain, and diseases affecting the central nervous system are in short supply. These shortages may have affected up to 92 percentage of cancer patients in the fall of 2012.
Health care systems themselves may create access barriers. Medication use increases when patient are covered by programs such as Medicare Part D or receive gap coverage under the Affordable Care Act.
When nonadherence is suspected, physicians should take the time to consider which factors are most applicable to a particular patient. Developing and implementing effective interventions require an understanding of all the elements affecting adherence, and targeting those that are both relevant and susceptible to change.