A gap analysis approach to assess patient persistence with glaucoma medication

Area of Science:

• Ophthalmology
• Pharmacoeconomics
• Health Services Research

Background:

• Patient persistence with prescribed medications is crucial for managing chronic conditions like glaucoma.
• Intraocular pressure (IOP)-lowering prostaglandin analogs are commonly prescribed, making them a suitable model for studying medication persistence.
• Accurate measurement of patient persistence is essential for evaluating treatment effectiveness and identifying barriers to adherence.

Purpose of the Study:

• To develop and validate an alternative method for assessing patient persistence with IOP-lowering medications.
• To utilize prostaglandin analogs (latanoprost, travoprost, bimatoprost) as a model to test the proposed analysis method.
• To compare the novel gap analysis method with traditional Kaplan-Meier survival analysis for measuring medication persistence.

Main Methods:

• A retrospective analysis of prescription refill data from a retail pharmacy database.
• Identification of patients with claims for specific prostaglandin analogs between September 2002 and December 2002.
• Definition of "gaps in therapy" as periods exceeding 45, 60, or 120 days without medication refills.
• Categorization of patients based on the number and duration of therapy gaps.
• Conducting a Kaplan-Meier survival analysis with a 120-day allowable refill period.

Main Results:

• Using a 120-day threshold, 77.5% of patients had no gaps in therapy, and 86.5% had 30 days or fewer off therapy annually.
• The gap analysis revealed significant differences in persistence based on the chosen gap threshold (e.g., 50.7% had ≥3 gaps with a 45-day threshold vs. 0% with a 120-day threshold).
• Kaplan-Meier analysis indicated 88.6% and 76.1% of patients remained persistent for 120 days and one year, respectively.

Conclusions:

• The proposed gap analysis method may offer a more clinically relevant assessment of patient persistence compared to standard Kaplan-Meier curves.
• This approach better reflects the reality of patients intermittently stopping and restarting medications.
• The gap analysis can help identify specific areas for further investigation into the reasons for patient non-persistence.