Monitoring adherence rates in glaucoma patients using the Travatan Dosing Aid. A 6-month study comparing patients on travoprost 0.004% and patients on travoprost 0.004%/timolol 0.5% fixed combination

OBJECTIVE:
To assess adherence in glaucoma patients using the Travatan Dosing Aid (TDA); to record differences in adherence by age, sex, therapy, systemic therapies, years from diagnosis, type of therapy and intraocular pressure (IOP).
RESEARCH DESIGN AND METHODS:
Sixth-month cohort study; fifty-six Caucasian, primary open-angle glaucoma patients on travoprost (T) or travoprost/timolol fixed combination (TTFC) monotherapy were submitted to four visits: at baseline and months 1, 3 and 6 (M1, M3, M6). Adherence was recorded with TDA and classified as 'high' if greater than 90%. Self-reported and physician-presumed adherence data were collected. Kruskall-Wallis and Fisher's exact tests were applied.
RESULTS:
Thirty-two patients (54.2%) were treated with T. Age, sex, level of schooling, presence of systemic comorbidities, duration of current therapy and IOP were similar between T and TTFC. Seventeen subjects (30.3%) recorded high adherence at every visit, 13 (23.2%) at two visits, 26 (46.4%) otherwise. Adherence was maintained over time with a slight decrease from month 1 to month 6 without statistical differences within and between groups. Adherence was statistically influenced by age (p = 0.007) and duration of therapy (p = 0.004).
CONCLUSION:
The typical nonadherent patient is elderly. TDA records indicate that only a minority of patients are really adherent: predictive models to screen for poor adherence are needed.