Patterns of adherence behaviour for patients with glaucoma

Aims and purpose Adherence to long-term treatment regimens for primary open-angle glaucoma holds a challenge for both clinicians and patients. The study aims were to (i) establish the magnitude of travoprost non-adherence using an Electronic Adherence Monitor (EAM), (ii) compare electronic with patient self-reported adherence, and (iii) explore the application of a previously reported method of graphically presenting adherence data to a larger cohort over a longer monitoring period. Methods A cohort study of patients using travoprost for glaucoma or ocular hypertension was conducted. All participants used an EAM and adherence data were collected prospectively for 2 months. Self-reported adherence was obtained using the Morisky Medication Adherence Scale (MMAS); patients also reported frequency of missed doses. Potential predictors of adherence were collected via a structured interview. EAM-recorded interdose intervals were plotted graphically. Results Of 100 patients invited to participate, 98 consented and EAM data were collected successfully from 88 participants. The median EAM adherence score for the cohort was 88.9% (interquartile range: 71.2, 92.2). When dichotomised (=80%: adherent; <80%: non-adherent), EAM identified 36.7% as non-adherent and MMAS 12.2%. EAM data were used to classify five types of adherence behaviour including a category representing levels of =97% maintained by 21% of participants. Conclusion EAM revealed good adherence to glaucoma monotherapy but poor agreement with patient self-reported adherence. An adherence category of persistent and exceptionally high adherence to travoprost over a 2-month period was identified.