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Adherence to Glaucoma Medical Therapy

Lisa S. Gamell, MD; Norberto Mancera, MD; and Gretta Fridman, MD

One of the great clinical challenges in the management of glaucoma is getting patients to adhere to a therapeutic regimen. C. Everett Koop, former US Surgeon General, famously remarked, “Drugs don’t work in patients who don’t take them.”¹ The magnitude of this problem has gained more attention in recent years, as evidenced by the increasing number of studies and publications designed to aid the physician in identifying and addressing the issue of poor adherence to glaucoma medical therapy.

Adherence is best defined as the degree to which a patient correctly takes his or her medication as directed by his or her physician. Therefore, if a patient is to take a beta-blocker drop twice a day and only remembers to take it once a day for 24 of the 30 days, then they have a 40% rate of adherence (24 doses divided by 60 total expected doses).² Adherence to chronic therapy in glaucoma has been estimated to be at 70% or less even as early as 2 months into treatment, and with further decline after that.³ It has been compared to other systemic conditions that are also asymptomatic to the patient and are associated with serious outcomes and for which monitoring is usually done at the doctor’s office, such as arterial hypertension and hypercholesterolemia.^4–8 Patients may not comprehend that lifelong treatment is necessary for glaucoma, whereas for other systemic conditions, lifestyle modifications such as weight loss and exercise can reduce their drug burden. On the other hand, consistent reduction in intraocular pressure (IOP) has been reported to reduce a risk of glaucoma progression, decreasing the risk of optic nerve damage and visual field deterioration.^9–11

In general, physicians have difficulty detecting if patients are adherent with glaucoma medical therapy. Studies^6,12,13 have demonstrated that most physicians significantly overestimate their ability to identify patients who are not taking their medications, thereby limiting opportunities to assess and modify barriers to adherence. Many physicians underestimate the role of risk factors and their own influence on the patient’s adherence. The risk factors for poor adherence have recently been classified into 4 categories: patient factors, provider factors, medication regimen, and situational factors.¹⁴

Patient factors include the patient’s motivation and understanding of the health benefits of the treatment, remembering to administer drops, physical ability and dexterity for drop administration, and comorbidities—other systemic illnesses that may also require medication use. Many of the glaucoma patients are older with impaired visual acuity and other physical and cognitive ailments, limiting their ability to identify and instill drops correctly. In one study,¹⁵ patients who had someone else administer the drops for them were more likely to find it difficult to remember taking their drops in the absence of their caretaker. Some of these factors can be modified, such as clear labeling, large-print regimen handouts, and reminder phone calls. Regarding the patient’s ability to get the drop successfully in the eye, a study was performed using a novel eye drop imaging monitor, and data indicated that approximately one-third of patients were missing their eye when administering their medication. The patients in this study also significantly overreported the amount of drops they got in their eye. The purpose of this study was then to provide health care providers with the ability to coach their patients on drop application techniques.¹⁶ Other factors, such as a patient’s level of education (with lower level of education being associated with poor adherence) cannot be altered.

Provider factors include the patient’s perception of the relationship with the physician, the ability to communicate and understand the medication regimen, as well as the satisfaction with the care received.17 Motivating patients to learn more about the disease and encouraging active participation in setting therapeutic goals can be achieved by the physician or office staff.¹⁸ Of note, not understanding the chronic nature of glaucoma medical treatment is a significant reason for patients discontinuing topical therapy.

Regimen factors include the cost of the medications, the complexity of the medication schedule, and side effects. Although cost is important in glaucoma therapy, it was not found to be a consistent factor significantly affecting adherence.⁸ One study¹⁹ found the highest adherence to medication regimen was when taking a prostaglandin analog, which also had one of the highest copayments. On average, the more complicated the dosing regimen, the higher the likelihood of adherence problems. It was shown that patients have greater adherence when on combination eye drops as opposed to multiple individual drops. In practice, balancing the cost of the medications may be difficult, while trying to simplify the regimen, such as using combination drops, and finding the medications that will minimize the side effects.²⁰

Situational factors consist of other life events interfering with the ability to administer medications. Major life changes, such as birth or death in the family, jobs with demanding schedules, travel, or being away from home, are associated with poor adherence.¹⁴ Most situational factors cannot be directly modified by a physician but rather influenced by increasing the patient’s knowledge and understanding about the disease and the need for consistent treatment.

The Glaucoma Adherence and Persistency Study (GAPS) is the largest study to date looking at adherence to topical medication by patients with glaucoma.^3,12,19 GAPS used medication possession ratio (MPR) as the measure for adherence to therapy. MPR is the number of days of prescription supply dispensed divided by the number of days between the first and last prescription refill. An MPR of 1.0 indicates that the patient possessed all the medication necessary for complete adherence. Any MPR less than 1.0 indicates less-than-complete adherence.

Data from 10,260 participants²¹ were analyzed. The mean MPR for the GAPS cohort was 0.64.²¹ GAPS identified 8 of the following independent variables that lowered the MPR by up to 34%:

1. Hearing all of what you know about glaucoma from your doctor (compared with some or nothing)
   
2. Not believing that reduced vision is a risk of not taking medication as recommended
   
3. Having a problem paying for medications
   
4. Difficulty while traveling or being away from home
   
5. Not acknowledging stinging and burning
   
6. Non-White individual
   
7. Receiving samples
   
8. Not receiving a phone call visit reminder

While a physician can attempt to address some of these barriers to adherence, others are inherent to the patient and cannot be modified. GAPS also identified different learning styles among patients to highlight the importance of a tailored, patient-centered approach.

The first step toward improved adherence is detection. Recognizing nonadherence can be a difficult task in the typically short encounter the physician has with the patient. Patients are reluctant to admit nonadherence as they do not want to be perceived as bad patients.²² Some will even demonstrate a “white coat influence,” where they will start taking their medications more diligently the days leading up to their appointment to ensure their IOP is within range, and when asked if they have been taking their medications as scheduled will confirm adherence. Using a 4-step adherence assessment interview as described by Hahn²² can help a physician identify and address problems with adherence. The first step is to find out what the patient understands about his or her medication regimen by asking an open-ended question about taking medication. The second step is to explicitly acknowledge that taking medication is difficult and that forgetting or missing a dose is understandable. The third step is to ensure that the patient understands that treatment decisions depend on knowing the actual regimen adhered to by the patient. Thus, if the IOP is elevated at the time of the visit, it is important to convey to the patient that admission to the nonadherence might avoid the unnecessary escalation in therapy. The final step is to ask directly about adherence. It is important that this step would be the last in this sequence as direct questioning early on might lead to false assurance of adherence.²² Once nonadherence is established, the specific barriers can be identified and addressed.

In order to improve a patient’s adherence, his or her motivational factors have to be understood. If the perception of the need for treatment does not outweigh the concerns about the medication use, the patient is unlikely to be adherent. Therefore, education should be targeted toward increasing the patient’s knowledge of the disease and its course. The manner in which this is done can play a dramatic role in altering adherence. All too often, physicians start out with a manufactured speech they give all of their patients. Although they may modify it to the patient’s perceived education level, and even give an opportunity to ask questions at the end, this approach may not be very successful. Often, patients already have certain understandings and beliefs, which they may not know how to merge with the information provided. Instead, a better approach is to use ask-tell-ask¹⁷ dialog. In this model, the physician first asks the patient about his or her current understanding and concerns about the disease and treatment. This gives the physician an opportunity to learn not only what the patient knows about the disease but also any incorrect information the patient might believe. It also provides a framework for discussion, as the physician can add to the information the patient already possesses. After completing the tell, another ask is required to assess if the patient has understood and internalized the information and to give the patient the opportunity to clarify any concerns. It is important that open-ended questions are used to prompt the patient to verbalize comprehension.22

Being actively aware of the adherence barriers is the first step in battling nonadherence. Identifying patients at risk and the barriers at hand is the next logical step. Providers should design and implement strategies and interventions that work for their practice. Some strategies may include the following:

• Trying to address adherence problems early on
  
• Training office staff to educate patients about glaucoma and the importance of treatment
  
• Simplifying regimens, reviewing medications at each visit
  
• Assessing and reducing side effects
  
• Keeping a medication diary
  
• Using telephone/text reminders
  
• Large-print handouts that are easy for patients to understand
  
• Working with patients’ insurance companies to minimize cost
  
• Being supportive and encouraging open communication²³

Lastly, it is important to remember that patients can regress at any time, so adherence assessment is a long-term undertaking—just as is glaucoma medical therapy.

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