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

Dong Yun Yeon; Chungkwon Yoo; Ji Hye Park; Ji Yun Han; Yong Yeon Kim

doi:10.3341/jkos.2015.56.6.906

Journal List > J Korean Ophthalmol Soc > v.56(6) > 1010304

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Yeon, Yoo, Park, Han, and Kim: Adherence to Preservative-Free Dorzolamide/Timolol Fixed Combination Assessed by Counting the Unused Single-Dose Units

Original Article

J Korean Ophthalmol Soc 2015;56(6):906-910.

Published online: 7 September 2015

DOI: https://doi.org/10.3341/jkos.2015.56.6.906

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

Dong Yun Yeon, MD, Chungkwon Yoo, MD, PhD, Ji Hye Park, MD, Ji Yun Han, MD, Yong Yeon Kim, MD, PhD

Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea

Address reprint requests to Chungkwon Yoo, MD, PhD Department of Ophthalmology, Korea University Anam Hospital, #73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Korea, Tel: 82-2-920-5521, Fax: 82-2-924-6820 E-mail: augen@lycos.co.kr

Received 24 October 201410 December 2014 Accepted 20 April 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 sin-gle-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. J Korean Ophthalmol Soc 2015;56(6):906-910

Keywords: Adherence, Dorzolamide/timolol fixed combination, Glaucoma, Single dose units

References

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Figure 1.

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

Figure 2.

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

Figure 3.

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

Table 1.

Patient characteristics

Variables	Data
Age (years, range)	57.71 ± 12.57 (34-79)
Sex (male/female)	16/18
Family history of glaucoma (n, %)	2 (5.9)
Diabetes (n, %)	6 (17.6)
Hypertension (n, %)	8 (23.5)
Spherical equivalent (diopter)	-1.37 ± 2.35
Untreated IOP (mm Hg)	17.0 ± 3.0
VFI (%)	85.2 ± 17.6
MD (dB)	-5.64 ± 5.57
PSD (dB)	6.24 ± 4.90
AL (mm)	24.4 ± 1.5
CCT (μ m)	532.4 ± 30.6

Values are presented as mean ± SD unless otherwise indicated. IOP＝ intraocular pressure; VFI＝ visual field index; MD＝ mean deviation; PSD＝ pattern standard deviation; AL＝ axial length; CCT ＝ central corneal thickness.

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