Does persistency truly equate to compliance?

Glaucoma patients commonly tell me that they are ‘taking their eyedrops religiously! ’ Does this imply that such patients are aware of the benefits of glaucoma medications to preserve vision (as in heaven) or face the fear of glaucoma induced blindness (as in hell)? ‘Religious’ beliefs are borne out of common everyday practices, and are in turn difficult to quantify. In this issue of the journal, Rait and Adena have applied a recognized form of applied pharmaceutical accountancy to help answer the question of how patients actually use prescribed eyedrops for glaucoma in the real world situation. This needs to be compared to the results of carefully constructed, randomized masked clinical trials where a select group of patients are enrolled and encouraged to use their medications in an exemplary fashion; the basis of sound, evidence-based medical science from which our treatments should be guided. Persistency is defined as ‘continuing obstinately; enduring; constantly repeated; and remaining instead of falling off in the normal manner. ’ In pharmaceutical parlance it is a measure of how a medication is used continuously by a patient. It is difficult to measure directly, but in the past patient diaries, returned emptied dropper bottles, and the observation of specific side effects (e.g., miotic pupils) have been equated to a measure of compliance and, over the longer term, persistence with a given treatment. Patients are knowingly involved in these measurements! In contrast the indirect method of measuring persistency by recording data related to the dispensing of medications captures information which is behaviourally independent. Additionally, such data can be collected retrospectively over a prolonged period and, as in this paper, applied to a large population. The definition of compliance is ‘to act in accordance with a request or demand; obedience. ’ The degree to which patients are compliant with medications is multifactorial, but in the pharmacology of eyedrops the major factors are frequency of application, ease of use, comfort, tolerability of side effects, and perceived benefits. For glaucoma, a chronic, non-life-threatening, asymptomatic condition, long-term compliance remains a major issue. Recent studies in Australasia have highlighted the significant trend towards prescription of prostaglandin analogues as first-line therapy in glaucoma. Therefore, it is pleasing to read in the current article that topical prostaglandin analogues, which are used once daily with minimal side effects, should have better persistency. Interestingly, the persistency at 12 months – even for the eyedrops that one would expect to have good compliance – is only in the order of 55%. None the less, the average drug resupply time is 28 days, suggesting patients and pharmacists are mutually aware of the importance of the regular timely supply of eyedrops. In the Melbourne Visual Impairment Project, it was found that 50% of patients with primary open angle glaucoma had not been previously diagnosed. This was deemed to be worrisome, especially because early detection of glaucoma is believed to be important for the effective prevention of visual loss. More recent studies of eye-care services in Melbourne concluded that compliance with recommendations still remains an issue and thus diseases leading to visual impairment, such as glaucoma and diabetic retinopathy, remain under-diagnosed in the elderly. The overall results of this current study suggest there is room for improvement for clinicians to develop creative ways to improve compliance over prolonged periods, to effect better persistency. Better persistency of treatment should reduce long-term vision loss from glaucoma, particularly in the current situation of recognized under-diagnosis in the ageing population. I believe this is a wake-up message for aspects of patient education. Even with medications that one would associate with better compliance, there seems to be evidence of complacency. Perhaps more effective evangelical preaching of patient education to our glaucoma flock in respect to the benefits of prolonged, persistent treatment is required.