A study to assess the feasibility of undertaking a randomized controlled trial of adherence with eye drops in glaucoma patients

BACKGROUND: Adherence with therapy could influence the progression of glaucoma and ultimately affect the onset of visual impairment in some individuals. This feasibility study evaluated the measures to be used for a future randomized controlled trial assessing the effects of group-based education on adherence with eye drops. METHODS: People diagnosed with glaucoma within the previous 12 months attending a regional ophthalmology clinic in the North West of England were recruited. A two-session education program delivered one week apart had been devised as part of a previous project. A combined adult learning and health needs approach to education was taken. Outcomes measured were knowledge of glaucoma, self-report of adherence, illness perception, beliefs about medicines, patient enablement, and general health (Short Form-12). Adherence was also measured objectively using a Medical Events Monitoring System device. RESULTS: Twenty-six participants consented to undertake the educational program and 19 produced analyzable data. Knowledge of glaucoma, illness perception, beliefs about medicine, and patient enablement all showed statistically significant improvements after education. Mean adherence with eye drops was maintained above 85% before and for 3 months after attendance at the educational program. Self-report exaggerated adherence by at least 10% when compared with the objective Medical Events Monitoring System data, and in fact the kappa agreement was zero. CONCLUSION: All questionnaires other than the Short Form-12 were considered to be valuable measures and use of a Medical Events Monitoring System device was considered to be an objective surrogate measure for adherence with eye drops. A multicenter, randomized, controlled equivalence trial of group versus individualized education using adherence as the primary outcome is the next step.