Purpose: To assess patient adherence and behaviors with topical once-daily therapy for glaucoma.
Design: Prospective, observational cohort study.
Participants: One hundred ninety-six patients with glaucoma who were being treated with a prostaglandin analog in 1 or both eyes at the Scheie or Wilmer Eye Institutes between August 2006 and June 2007.
Methods: Detailed medical history was obtained from each patient. All subjects used the Travatan Dosing Aid (DA; Alcon, Fort Worth, TX) to administer travoprost as prescribed. Devices were collected at 3 months and the data of drop usage was downloaded using software provided with the dosing aid. Data were analyzed for the 8-week period starting 2 weeks after the enrollment visit and ending 2 weeks before the 3-month visit.
Main outcome measures: Assessment of adherence and patterns of drop usage as indicated by the DA.
Results: A total of 282 subjects consented to be in the study and 86 (30%) withdrew before study completion or had device errors, leaving 196 subjects (70%) with evaluable data at 3 months. The overall mean (+/-standard deviation) adherence rate was 0.71 (+/-0.24), ranging from 0.02 to 0.97. One hundred nine of these patients (55.6%) took greater than 75% of the expected doses. Those with adherence of less than 50% of expected doses showed substantially increased dose taking immediately after the office visit and just before the return visit at 3 months (P = 0.03). The mean adherence rate estimates of the physician and patient self-report were 0.77 and 0.95, respectively. The agreement between the physician assessment and DA-recorded adherence rate showed poor correlation for individual cases (intraclass correlation coefficient, 0.09; 95% confidence interval, 0.00-0.19).
Conclusions: Nearly 45% of patients using an electronic monitoring device who knew they were being monitored and were provided free medication used their drops less than 75% of the time. Patients reported far higher medication use than their actual behavior. The ability of the physician to identify which persons are poorly adherent from their self-report or from other subjective clues is poor.
Financial disclosure(s): Proprietary or commercial disclosure may be found after the references.