Patients' adherence to drug therapy to control chronic diseases is notoriously poor, particularly when the disease is asymptomatic. Moreover, self-reporting of adherence correlates very poorly with reality. How can you improve this situation?
PERSISTENCY AND ADHERENCE
Two terms are used frequently in the literature. Persistency is the opposite of discontinuation; the patient continues to refill the medication, and the physician continues to prescribe the medication, although doses may be missed or some lapses may occur between refills. Persistency data have usually been presented as a Kaplan-Meier survival curve. Adherence is a replacement term for compliance, in which the patient's responsibility is added as a component. Adherence is most commonly shown in the literature as the medication possession ratio (MPR), in which the number of daily doses of dispensed medication is divided by the days between the initial prescription and refill.
In glaucoma, approximately 60% to 65% of patients are able to consistently take one drop of a prostaglandin analogue per day on a long-term basis.1-7 Several studies have shown prostaglandins have the highest persistence among glaucoma medications.7-11 Drugs requiring less frequent dosing are clearly a better choice than those requiring more frequent dosing.12 Cycling behavior is also quite common1-3,13; patients resume administering a medication shortly prior to an upcoming appointment and continue briefly thereafter, a phenomenon known as white-coat adherence.14
Tsai showed 71 discrete barriers to patients' adherence to glaucoma therapy.15 The Glaucoma Adherence and Persistency Study (GAPS)1-3 identified patients' characteristics that affect adherence. The design of GAPS was novel, as previous studies looked only at pharmacy claims data. GAPS combined pharmacy claims data (n = 13,956) with reviews of patients' charts as well as interviews with physicians and patients.3 The most commonly reported barriers1 were concern about side effects (67%), difficulty using drops correctly (36%), and cost (25%). The GAPS multivariate analysis showed the following factors associated with nonadherence:
• a lack of concern about the risk of vision loss from
nonadherence
• an exclusive dependence on the doctor for learning
about glaucoma
• difficulty taking medications when traveling and
away from home
• the cost of medications
• the patient's failure to acknowledge ocular stinging
or burning
• race other than white
• receipt of samples
The GAPS showed that adherence improved with the doctor's use of phone call appointment reminders.
STEP NO. 1. ASK QUESTIONS EFFECTIVELY
The first step in improving adherence is assessing it in a fashion that is neither threatening nor judgmental.16,17 The technique of asking patients about adherence has certain subtleties that can greatly alter the information provided. Ask first what medication they are taking. Patients who cannot name their medication or dosing frequency have a lower rate of adherence.18 Inquire about difficulties they are having with their medication (eg, cost, running out, side effects, forgetfulness, and challenges with either self-administration or requiring someone else to administer the drops). Do not assume patients are able to administer their drops19,20; ask them to demonstrate their methods with a bottle of artificial tears in front of you or your staff and make improvements to their technique.
STEP NO. 2. FIND OUT WHAT PATIENTS KNOW
Ask patients to state their understanding of glaucoma and the benefits of using drops. Their answers can be quite revealing of their individual barriers. Moreover, correcting their misconceptions—particularly about the risk of vision loss—is an important part of improving compliance.1 The doctor-patient interaction is a key component of assessing and improving adherence. A study of videotaped doctor-patient interviews showed that physicians talk 70% of the time and do not ask questions or allow the patient to ask questions.21 Openended questioning of the patient with an understanding, normalizing style has been shown to be a more effective approach.16,17
STEP NO. 3. LEARN ABOUT MISSED DOSES
After steps 1 and 2, ask patients how many times per week or per month they have missed taking their medication and when they last used their drops. Simplify the dosing regimen as much as possible; patients who have two eye drop prescriptions to keep filled are generally less persistent than those on monotherapy.22,23 Assess cost and prescription coverage when making prescribing decisions. Provide written directions on the drops' usage for the patient, because they can greatly improve adherence.24
The GAPS showed patients' choice of words informative. 1 “Forgetting” covers a multitude of sins, whereas “skipping” tends to be very specific for nonadherence and correlates with a low MPR. Although 90% of patients interviewed in the GAPS reported taking their drops daily, the MPR from their pharmacy claims data showed that only 64% of patients had enough medication in their possession to be able to take the drops each day.
Discuss the patients' dosing schedules, including where they keep their medication and how it fits into their daily routine. Ask if they miss their drops more in the AM or PM and revise their dosing schedule or link it accordingly to a daily part of their routine. For patients who miss morning drops on the way to work, suggest they keep an extra bottle at their workplace. Make recommendations such as keeping the drops near the coffee pot for morning dosing, keeping the bottle by the toothbrush, and programming cell phone reminders. Research has found mixed results with devices such as the Travatan Dosing Aid (Alcon Laboratories, Inc., Fort Worth, TX).25-27
Patients who do not keep follow-up appointments have been shown to have worse adherence than those who do.2,5,13,28 The GAPS showed that phone call reminders, as opposed to no reminder or a postcard/letter, significantly improved patients' keeping of appointments.2 Keep track of patients who do not follow up and make a phone call or send a certified letter to those who do not reschedule.
Be sensitive to economics. Patients may be embarrassed by their inability to afford copayments or the cost of drops. Offer pharmaceutical company assistance programs to patients who qualify. Beware of patients who rely on samples; again, the GAPS showed this to be an indicator of poor adherence.3
CONCLUSION
“Medications only work for patients who take them.”29 By determining which of your patients are missing doses and why, you can help them to adhere to glaucoma therapy and preserve their health.
Gail F. Schwartz, MD, is in practice with Glaucoma Consultants, Greater Baltimore Medical Center, and is an assistant professor at the Wilmer Eye Institute of Johns Hopkins University in Baltimore. She is a consultant to, is on the speakers' bureaus of, and has received research support from Allergan, Inc., and Pfizer Inc. Dr. Schwartz may be reached at schwartzgf@aol.com.
