J Korean Ophthalmol Soc.  2015 Jun;56(6):906-910. 10.3341/jkos.2015.56.6.906.

Adherence to Preservative-Free Dorzolamide/Timolol Fixed Combination Assessed by Counting the Unused Single-Dose Units

• Yeon DY
• Yoo C
• Park JH
• Han JY
• Kim YY

• KMID: 2339156
• DOI: http://doi.org/10.3341/jkos.2015.56.6.906

Abstract

PURPOSE
To investigate the actual adherence to treatment with preservative-free dorzolamide-timolol fixed combination (DTFC) eyedrops of primary open-angle glaucoma (POAG) patients by counting the number of unused single-dose units of DTFC.
METHODS
This study included 34 POAG patients newly prescribed with preservative-free DTFC eyedrops (formulated in single-dose units). The enrolled patients were asked to bring the unused DTFC units on their next visit after 2 weeks of treatment with DTFC. On their second visit, they were asked to complete a questionnaire regarding the self-reported adherence and the number of unused DTFC single-dose units was counted. The actual adherence (%) was calculated by dividing the expected number of used DTFC units by the actual number of used DTFC units. The correlation between the self-reported adherence and the measured adherence was assessed.
RESULTS
Twenty-nine (93.5%) patients answered they adhered to the medication by more than 90% and 2 (6.5%) answered they instilled the eyedrops at 80-90% of the dosing schedule. However, after counting the unused DTFC single-dose units, 9 (29.0%) patients showed an actual adherence of <90%. Moreover, the actual adherence of 3 (9.7%) patients was <60%. Unexpectedly, 4 (12.9%) patients showed the actual adherence exceeding 100% (196%, 1 patient; 107-132%, 3 patients).
CONCLUSIONS
We demonstrated a large difference between the self-reported and the actual adherence to treatment by counting the unused single-dose units of eyedrops. Preservative-free topical anti-glaucoma medications (formulated in single-dose units) provide clinicians an opportunity to assess the actual adherence of glaucoma patients by counting the unused units of eyedrops.

Keyword

Adherence; Dorzolamide/timolol fixed combination; Glaucoma; Single dose units

MeSH Terms

Appointments and Schedules
Glaucoma
Glaucoma, Open-Angle
Humans
Ophthalmic Solutions
Surveys and Questionnaires
Ophthalmic Solutions

Figure

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  Figure 1. Number of patients complaining of uncomfortable side effects of preservative-free dorzolamide-timolol fixed combination.

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  Figure 2. Graph showing the percentage of prescribed doses taken by patients (x-axis) and the percentage of patients (y-axis).

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  Figure 3. Scatterplot showing the Spearman’s correlation between the self-reported adherence (x-axis) and the measured adherence (y-axis) (p＝0.064).

Reference

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