Study on Incentives for Glaucoma Medications Adherence (SIGMA)

Glaucoma topical eye medications, when adhered to, are effective at controlling disease progression. Yet evidence shows that many glaucoma patients have incomplete adherence to medications, with disease progression resulting in significant costs to the patient and health system. Through the approach of value pricing, a link can be made between non-adherence and its resulting costs by granting subsidies to adherent patients for their medications and physician visits. This 6-month randomized controlled trial among 100 glaucoma patients from the Singapore National Eye Centre aims to test the extent to which value pricing can improve medication adherence.

By reducing intraocular pressure, glaucoma topical eye medications are effective at controlling disease progression for the majority of patients. Yet evidence shows that many glaucoma patients have incomplete adherence to medications, resulting in significant personal costs in terms of disease progression and visual field loss. The cost to the health system from poor adherence is also substantial as glaucoma surgery is more costly than treatment with topical medication. Behavioural economics theory suggests that adherence rates can be improved by providing a clearer link between non-adherence and the resulting costs thereof. In the proposed study, this link is made by granting subsidies to adherent patients for their medications and physician visits, whereas those who are not sufficiently adherent would not receive the subsidy and thus pay a higher rate for their treatment. These subsidies provide a financial incentive for patients to take their medicines as prescribed, and because prescription refills and visits occur regularly, also provide a tangible and near-term cost resulting from non-adherence. The investigators refer to this approach as value pricing as subsidies are allocated to medications that have not only been shown to be clinically effective but that are also effectively used by the patient. In efforts to increase adherence among glaucoma patients in Singapore, the investigators propose to conduct a 6-month proof-of-concept randomized controlled trial among 100 participants from the Singapore National Eye Centre (SNEC) to test the extent to which value pricing can improve medication adherence. As Singapore's population continues to age and a larger share of the population requires daily medications to treat chronic diseases, such innovative solutions are needed to ensure not only that patients take their medications as prescribed and receive the full benefit of their treatment but also that Government subsidies are allocated effectively so that to ensure the sustainability of the health system. Specific Aim and hypothesis tested: Aim: Test whether adding Value Pricing (VP) to Usual Care (UC) can improve medication adherence over a 6-month period. Hypothesis: VP patients will show greater adherence rates at 6 months compared to those receiving only UC.

Patients receiving Usual Care for Glaucoma comprising: Education on effective glaucoma treatment Routine check-ups with an ophthalmologist and prescription of glaucoma eye drops Glaucoma counselling [Can be recommended by ophthalmologist for non-adherent patients] covering: Glaucoma risk factors and symptoms Management and treatment Medications and optimal dosage windows Risks of medication non-adherence Formulation of a dosing schedule that compliments each patient's lifestyle

Patient receiving Usual Care for Glaucoma and given the opportunity to receive Value Pricing Subsidies.

Usual care for glaucoma Subsidies granted to adherent patients for their glaucoma medications and physician visits, lowering the costs of treatment and providing a financial incentive for patients to take their medicines as prescribed. Subsidy (25 / 50%) granted based on meeting dose-rate adherence percentage targets (75 / 90%) at the month 3 and 6 assessment points.

The proportion of days across a month where a patient took all medication(s) within the appropriate dosing windows (morning, afternoon, evening) for the day.

The proportion of days across the study period where a patient took all medication(s) within the appropriate dosing windows (morning, afternoon, evening) for the day.

The proportion of participants at each time point who met the 90% dose-rate adherence percentage cut-off for each monitoring period.

The percentage of participants at each time point who met the 75% dose-rate adherence percentage cut-off for each monitoring period.

Scale to measure quality of life, pertaining specifically to aspects of QoL that can be affected by the glaucoma condition.

Inclusion Criteria: Singaporean citizens or permanent residents Conversant in English or Mandarin Taking at least one glaucoma eye drop medication Shown to be non-adherent based on a value of 6 or less on the Modified Medication Adherence Scale (MMAS) Exclusion Criteria: Significant comorbid conditions preventing application of medications without assistance Stage 4 (advanced) or Stage 5 (end stage) glaucoma according to the Glaucoma Staging System

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