Medication adherence and health care costs with the introduction of latanoprost therapy for glaucoma in a Medicare managed care population.

BACKGROUND: Latanoprost, a prostaglandin inhibitor, is increasingly being used in the therapeutic management of glaucoma. However, there is scant literature examining the cost and outcome ramifications of latanoprost.
OBJECTIVES: This study examined the medication use behavior (medication-related persistence and adherence rates) and costs associated with the introduction of latanoprost therapy in a treatment-naive older population (aged >or=65 years) enrolled in Medicare.
METHODS: The study employed a retrospective observational cohort design and used administrative claims data from a Medicare health maintenance organization (HMO), which offered complete coverage to enrollees, including prescription benefits. The case group consisted of patients with glaucoma who began latanoprost therapy. The control group consisted of enrollees with glaucoma who started any therapy other than latanoprost. Both groups were followed up for 1 year before and after initiation of therapy. Bivariate and multivariate techniques incorporating health care utilization in the year before the start of new therapy were used to determine the study outcomes.
RESULTS: The case group comprised 101 patients (mean age, 77.60 years), while the control group included 168 patients (mean age, 77.59 years). There were no significant differences across the 2 groups with respect to age, sex, general health scores on the 12 item Short-Form Health Survey, severity of comorbidity, or the proportion of respondents with perception of worsened health. Introduction of latanoprost therapy was associated with higher medication persistence (hazard ratio, 0.90; 95% CI, 0.68-0.98) and adherence rates (mean [SD], 0.51 [0.26] vs 0.40 [0.25]; P < 0.001) compared with patients starting other glaucoma medication. Furthermore, there were no additional increases in total health care costs in the entire population associated with the introduction of latanoprost therapy, after adjusting for group and time effects, as well as other confounders (mean [SD], $4718.24 [$8982.92] vs $4046.55 [$6505.39]).
CONCLUSIONS: Latanoprost therapy offered improved medication use behavior in these older adults enrolled in a Medicare HMO. There were no significant additional increases in overall health care costs as a result of introduction of latanoprost therapy, after adjusting for group and time effects, as well as other baseline confounders in this study cohort.