Patterns of Glaucoma Medication Adherence over Four Years of Follow-Up

• Published in: Ophthalmology (Rochester, Minn.) Vol. 122; no. 10; pp. 2010 - 2021
• Main Authors: Newman-Casey, Paula Anne, MD, MS, Blachley, Taylor, MS, Lee, Paul P., MD, JD, Heisler, Michele, MD, MPA, Farris, Karen B., PhD, Stein, Joshua D., MD, MS
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2015
• Subjects: Aged; Antihypertensive Agents - therapeutic use; Female; Follow-Up Studies; Glaucoma, Open-Angle - drug therapy; Humans; Intraocular Pressure - drug effects; Male; Managed Care Programs - statistics & numerical data; Medication Adherence - statistics & numerical data; Middle Aged; Ophthalmology; Retrospective Studies; open-angle glaucoma; SD; ICD-9-CM; OAG; GBTM; medication possession ratio; CI; International Classification of Diseases, Ninth Revision, Clinical Modification; group-based trajectory modeling; confidence interval; MPR; standard deviation
• ISSN: 0161-6420; 1549-4713
• DOI: 10.1016/j.ophtha.2015.06.039

Purpose To assess longer-term patterns of glaucoma medication adherence and identify whether patterns established during the first year of medication use persist during 3 subsequent years of follow-up. Design Retrospective, longitudinal cohort analysis. Participants Beneficiaries aged ≥40 years who were enrolled in a United States (US)-managed care plan for ≥7 years between 2001 and 2012 and newly diagnosed and treated for open-angle glaucoma. Methods For each enrollee, we quantified medication adherence using the medication possession ratio. Group-based trajectory modeling (GBTM) was applied to identify patterns of adherence for 1 and 4 years of follow-up. The percent of beneficiaries who remained in the same trajectory group in the 1- and 4-year models was tabulated to evaluate group stability. Factors impacting adherence at 1 and 4 years were identified using regression analyses. Main Outcome Measures Patterns of glaucoma medication adherence. Results Of the 1234 eligible beneficiaries, GBTM identified 5 distinct glaucoma medication adherence patterns in both the 1-year and 4-year follow-up periods. These groups were as follows: (1) never adherent after their index prescription fill (7.5% and 15.6% of persons in the 1- and 4-year models, respectively); (2) persistently very poor adherence (14.9% and 23.4% of persons in the 1- and 4-year models, respectively); (3) declining adherence (9.5% and 9.1% of persons in the 1- and 4-year models, respectively); (4) persistently moderate adherence (48.1% and 37.0% of persons in the 1- and 4-year models, respectively); and (5) persistently good adherence (20.0% and 15.0% of persons in the 1- and 4-year models, respectively). More than 90% of beneficiaries in the 4 groups with the worst and best adherence patterns (groups 1, 2, 3, 5) maintained their patterns from their first year throughout their 4 years of follow-up. Those with persistently moderate adherence (group 4), the largest group, were most likely to change groups from 1 to 4 years of follow-up. Persons with the best adherence over 4 years were more likely to be white, to be older, to earn >$60 000/year, and to have more eye care visits ( P < 0.05 for all comparisons). Those with a higher initial copayment cost had lower adherence rates (β = −0.06/dollar, P  = 0.03). Conclusions For most patients who were newly prescribed glaucoma medications, adherence patterns observed in the first year of treatment reflect adherence patterns over the subsequent 3 years. Investing resources in both identifying and helping patients with suboptimal adherence patterns over the first year may have a large impact on longer-term adherence.