Modeling the Pharmacotherapy Cost and Outcomes of Primary Open-Angle Glaucoma With Dry Eye

Abstract

We aimed to analyze and model the cost and results of current outpatient pharmacotherapy practice in patients with primary open-angle glaucoma concomitant with dry-eye disease (POAG+DE). The point of view is that of the health care system and patients, and the time horizon was 1 year. Data were collected through a prospective, observational, real-life study of therapy practice in patients admitted to the specialized ophthalmology clinic at the Alexandrovska University Hospital in Sofia. Pharmacotherapy was recorded and analyzed by therapeutic group and INN. The probability of being prescribed preservative-free or non-free formulations was calculated, as were the cost of yearly therapy, reimbursed cost, and patient co-payment. A decision tree exploring the cost-effectiveness of preservative-free and preservative non-free formulations was built. Outcomes were recorded through three tests measuring tear film stability: TMS, NIBUT Ave, and ST. TMS values below 3, ST above 10 mm, and NIBUT Ave above 14 s were considered as indicators of good disease control. A total of 140 eyes were diagnosed with POAG, of which 64 had concomitant dry-eye disease and were included in the analysis. Monotherapy was prescribed to 34: 14 on preservative-free formulations and 20 on non-free. Meanwhile, 30 eyes received combination therapy: six on preservative-free and 24 on non-free. The monotherapy product was most commonly Prostaglandin Analogs (PG-73.5%), followed by beta-blockers (BB-26.5%). No carbonic anhydrase inhibitors (Ca AA) or alpha-2 adrenergic agonists (alfa 2 AA) were prescribed as monotherapy. The majority of patients showed poor disease control according to all three measures. The incremental cost-effectiveness ratio (ICER) was 744 BGN for TMS and 131 BGN for NUBIT for each successfully controlled eye-far below three times GDP per capita. For ST, the ICER was negative, benefiting non-free formulations. Therapy of POAG+DED with preservative-free formulations is cost-effective according to the WHO threshold of three times GDP. The median costs of the two treatment modalities were similar. Current practice shows that patients experience a higher burden in terms of co-payment than do institutions such as the NHIF.

Keywords: cost-effectiveness; decision tree model; dry eye; glaucoma; pharmacotherapy.