Original Article
Knowledge of medications among patients
with glaucoma in Taiwan
Mei Lan Ko
a,b, Kai Lin Wei
c, Yi-Jung Ho
a, Pai Huei Peng
d,**
,
Henry Horng Shing Lu
c,*
a
Department of Ophthalmology, National Taiwan University Hospital, Hsin-Chu Branch, Hsinchu, Taiwan
b
Department of Biomedical Engineering and Environmental Science, National Tsing Hua University, Hsinchu, Taiwan
c
Institute of Biomedical Engineering, National Chiao Tung University, Hsinchu, Taiwan
d
Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
Received 5 April 2018; received in revised form 13 June 2018; accepted 9 July 2018
KEYWORDS
Glaucoma drugs; Identification; Knowledge; Recalling
Background/Purpose: To investigate the knowledge and learning ability of glaucoma patients regarding their anti-glaucoma topical medications.
Methods: Patients on regular follow-up at the Glaucoma Clinic at Hsin-Chu General Hospital were recruited. After detailed ocular examinations, the participants were asked to recall and identify their glaucoma eye drops. The same test was repeated 3 months later. The results of both tests, the learning ability of patients regarding their glaucoma drugs, and the relation-ship between learning ability and demographic variables were evaluated.
Results: Two hundred eighty-seven glaucoma patients participated in this study. Of the study population, 25.8% and 57.1% could recall their topical mediation at the first and second tests, whereas 72.1% and 88.5% could identify their prescribed eye drops at the first and second tests, respectively. Approximately 34% of the participants showed improved knowledge at the repeat test, whereas 40% of the participants showed no improvement. Participants with a better learning ability were more likely to be younger, with a higher level of education, and with less visual field impairment.
Conclusion: The knowledge of glaucoma patients regarding their prescribed medication was defi-cient in Taiwan. Physician effort could improve knowledge on the prescribed drugs. Patient-centered education should be considered, targeting elderly individuals, illiterate individuals, and those with loss of visual function to increase compliance with glaucoma medication. Copyrightª 2018, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/).
* Corresponding author. 4F, Assembly Building I, 1001 University Road, Hsinchu, Taiwan. Fax:þ886 3 572 8745. ** Corresponding author. No. 95, Wen Chang Road, Shih Lin District, Taipei, Taiwan. Fax:þ886 2 2838 9343.
E-mail addresses:paihuei@yahoo.com.tw(P.H. Peng),hslu@stat.nctu.edu.tw(H.H.S. Lu).
https://doi.org/10.1016/j.jfma.2018.07.011
0929-6646/Copyrightª 2018, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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Introduction
Glaucoma is one of the leading causes of irreversible blindness worldwide. A population-based study showed that one in 40 adults older than 40 years had impaired vision due to glaucoma.1 It is estimated that 59.51 million people would be affected by glaucoma by 2020.2Long-term use of topical eye drops to lower intraocular pressure (IOP) re-mains the first-line therapy for glaucoma.
Persistent adherence to anti-glaucoma regimens is crucial for treatment efficacy.3,4 However, similar to the findings on other chronic diseases, less than 50% of glau-coma patients persisted with therapy at one year.3 A population-based study in Taiwan showed that only 24.2% of newly diagnosed patients continued to refill their pre-scriptions after 2 years.5Several factors have been identi-fied to be associated with poor adherence such as patient and pharmacological characteristics,6e9 insufficient knowledge of drugs,10 and poor communication between
the physician and patient.8,11
Adequate knowledge of medication has been recognized as one of the determinants of treatment compliance. Be-sides, adequate recall of prescribed drugs is a reflection of understanding of the treatment regimen.12,13 The per-centage of patients able to accurately identify their drugs varies from 10.9% to 85%.11,14e17 Age, sex, household
in-come, use of multiple medications, a low level of educa-tion, and first-time prescription of medication for glaucoma patients were associated with deficient knowledge about medication.11,14However, to date, research on the
knowl-edge of medication on patients with glaucoma is limited. A study in the UK showed that knowledge of the name of the ocular disease and knowing the importance of the pre-scribed regimens were starting points to improve adher-ence.18 Bloand et al., found that glaucoma patients who
were non-adherent to treatment were less likely to name their medications correctly.19In another study, only 40% of
patients showed less than 100% accuracy when tested twice about the name and dosage of glaucoma medications.13We
conducted this study to further evaluate the knowledge and learning ability of glaucoma patients about their medica-tion. We conducted this prospective study at a glaucoma specialist clinic to investigate the level of knowledge of glaucoma patients about topical ocular hypotensive treat-ment. We also evaluated possible factors that contributed to knowledge regarding medication.
Methods
Patients at the glaucoma subspeciality clinic using one or more topical hypotensive medications in one or both eyes were recruited into this study. Study approval was obtained from the Institutional Review Boards of the Hsin-Chu General Hospital and the principles of the Declaration of Helsinki were followed. After obtaining informed consent, ocular and social information was collected on each patient. Detailed eye examination, including best-corrected visual acuity (BCVA, converted to the log MAR scale), slit lamp examina-tion, IOP measurement on a non-contact tonometer (TONOPACHY NT-530P, NIDEK co., LTD, Japan), fundoscopy, and visual field (VF) examination on an Octopus Visual Field
Analyzer (Interzeag AG, Berne, Switzerland), was per-formed. Only patients with at least two consecutive reliable VF results (false-positive and false-negative rate < 30%, fixation losses< 20%) were included. Patients with acquired color vision deficiency due to glaucoma, BCVA in the better-treated eye less than 0.1, inability to communicate, illiter-acy, use of different medications in either eye, cognitive disability, and inability to complete two knowledge tests were excluded from the study.
After ocular examination, a trained staff member asked patients to recall the names of their topical glaucoma drugs. If they were unable to remember all the drugs correctly, they were asked to identify their medications from nine distinct topical glaucoma eye drops placed randomly on a desk. After the test, participants were informed that the same test would be carried out three months later. If one more correct answer was noted at the second, compared to the first test (e.g., a patient on three types of medication recognized one drug at the first test and two drugs at the second test), the participant was assigned a score of 1.
The severity of visual field loss was categorized as mild, moderate, or severe according to the mean defect between 3 to 8, 8 to 12, or less than 12 dB, respectively. The time interval from the initial diagnosis of glaucoma was classified from 1 to 4 based on a history of less than 3 years, 3e6 years, 6e9 years, and more than 9 years. The educa-tional status was classified into 5 levels; level 0 if the participant had no diploma, level 1 if the participant was educated to the level of elementary school, level 2 if the participant was educated to junior high school level, level 3 if the participant was educated to high school level, and level 4 if the participant had attained post-secondary graduation. We analyzed learning ability regarding recall and iden-tification of medication as follows: Participants were assigned as level 1 if they did not recall or identify any glaucoma drug or showed no improvement of score at the repeat test; level 2 if they showed improvement in accu-racy at the second test and level 3 if they gave correct answers at both tests.
We used the R program software to perform statistical analysis. The Spearman’s rank correlation test was used to analyze the association between knowledge and discrimi-nation with various demographic factors. Multinomial lo-gistic regression test and classification tree were used to identify significant factors associated with improved learning ability. A p-value of<0.05 was set to determine statistical significance.
Results
Patient characteristics are summarized in Table 1. A total of 287 patients were enrolled in this study of which 180 (62.72%) were men. The mean age of the study population was 56.53 years (standard deviation, SD, 16.95) and the mean BCVA, 0.14 (SD 0.27). The mean VF loss of partici-pants was9.38 dB (SD 6.06).
Tables 2 and 3present recall and identification of topical glaucoma medications. Only 74 (25.8%) study participants recalled their medication at the first test. Three months later, at the repeat test, more than twice as many patients
(164 patients, 57.1%) could name their medications. As expected, visual identification of eye drops was easier than recall of names; 72.1% of participants could identify their eye drops at the first attempt, while 88.5% could do so at the second attempt.
The degree of improvement of recall and identification of topical glaucoma medications is shown inTables 4 and 5. Predictably, patients who were only on a single medication had the highest rates of recall at both tests; 31.72% at the first and 76.88% at the second test. Similar rates of improvement (level 2) in recall were found regardless of the number of prescribed eye drops (34.95% in patients on one drug, 32.44% in patients on two drugs, and 33.33% in patients on three drugs). Besides, patients on two drugs had a similar rate of improvement in identification compared with those on three drugs (28.38% vs. 23.24%). Overall, 34.15% of participants had improved knowledge of their medication at the second test (level 2), while 40.07% of participants showed no improvement (level 1).
Table 6 shows the relationship between the learning ability to recall or identify about topical glaucoma medi-cations and various demographic factors. Learning ability was positively associated with age, BCVA in log MAR (worse vision), less loss of VF, the duration of glaucoma, the number of eye drops, and the level of education. The ability to correctly identify medication was positively associated with less loss of VF and the level of education, and negatively associated with age, better vision, duration of glaucoma, and the number of glaucoma drugs.
Table 1 Demographic and ocular characteristics of study participants.
Patients’ data Results (% or SD)
Gender, male 180 (62.72%)
Age, years 56.35 (16.95)
Better-eye visual acuity, log MAR 0.14 (0.27)
Intraocular pressure, mmHg 14.60 (3.80)
VF mean defect
(average of both eyes), mean defect
9.38 (6.06)
Length of glaucoma, grade 2.21 (1.17)
Number of glaucoma drugs 1.45 (0.66)
Education, level 2.98 (1.26)
Results were expressed as mean and standard deviation (in parentheses) except number and percentage (in parentheses) in gender.
Table 2 Distribution of recalling of topical glaucoma medications.
With 1 drug With 2 drugs With 3 drugs
Number (%) Number (%) Number (%)
First test
Did not know any name of drugs 127 (66.28) 53 (71.62) 17 (62.96)
Knew 1 name of drugs 59 (31.72) 10 (13.51) 3 (11.11)
Knew 2 names of drugs NA 11 (14.86) 3 (11.11)
Knew 3 names of drugs NA NA 4 (14.81)
Second test
Did not know any name of drugs 62 (33.33) 35 (47.30) 12 (44.44)
Knew 1 name of drugs 124 (66.67) 10 (13.51) 1 (3.70)
Knew 2 names of drugs NA 29 (39.19) 3 (11.11)
Knew 3 names of drugs NA NA 11 (40.74)
Total 186 74 27
Table 3 Distribution of identification of topical glaucoma medications.
With 1 drug With 2 drugs With 3 drugs
Number (%) Number (%) Number (%)
First test
Did not identify any drugs 43 (23.12) 15 (20.27) 1 (3.7)
Identified 1 name of drugs 143 (76.88) 14 (18.92) 2 (7.41)
Identified 2 names of drugs NA 45 (60.81) 5 (18.52)
Identified 3 names of drugs NA NA 19 (70.37)
Second test
Did not identify any drugs 16 (8.6) 3 (4.05) 0
Identified 1 name of drugs 170 (91.40) 11 (14.86) 0
Identified 2 names of drugs NA 60 (81.08) 3 (11.11)
Identified 3 names of drugs NA NA 24 (88.89)
In Fig. 1, the classification tree shows the correlation between learning ability and eight variables. The numbers of participants at three different levels (from left to right: 1e3) are shown beneath the rectangles. The numbers in the rectangles represent the level with the most participants.
Participants without learning ability (level 1; groups A, B, E, and G) tended to be older than 69.5 years with a lower level of education (less than 1.5); or older than 69.5 years with a higher level of education (more than 1.5), but with severe VF loss (mean defect more than 14.88 dB); younger than 69.5 years with glaucoma of more than 9 years duration, and VF defect between4.775 and 16.75 dB; or younger than 69.5 years with glaucoma of less than 9 years duration, and mild VF loss between4.775 and 5.975 dB.
Discussion
Patients who could correctly recall their medications also had a better understanding of the effects of their medi-cations, according to a study conducted at primary healthcare facilities.11 Furthermore, patients who were
knowledgeable about their medication were more compliant with treatment than those who were not.10
Therefore, the ability to name the prescribed medications appears to be the critical step to establish effective adherence to glaucoma therapy. Our results showed that only a quarter of participants knew the name of their glaucoma eye drops. Despite being reminded of the second test, over 40% of participants failed to recall their drugs. Old age, low education level, and severity of VF loss were related to lack of improvement of knowledge of medication.
Older people are more likely to have chronic diseases. Therefore, adherence to medication is very crucial to prevent disease progression. However, only 40% of out-patients, 8% of elderly admissions, and 12% of elderly dis-charges could name their medications in a previous study.16
Patients with factors affecting adherence to glaucoma medication commonly seen in the elderly (physical or cognitive disability, lack of transport facility, and financial difficulties) were excluded from the present study.8It has
been previously shown that inability to remember and lack of literacy may contribute to deficient knowledge on medications among the elderly.11 Our findings corroborate with those of the above study; we showed that older pa-tients with a low education level and worse VF defect showed no improvement in naming or identifying their glaucoma drugs. However, two subgroups of participants younger than 69.5 years also revealed lack of improvement, including those with a shorter duration of glaucoma and minimal VF defect, and those with a longer duration of glaucoma and moderate loss of VF. The possible explana-tion for this finding could be that patients at an early stage of glaucoma may be unaware of the consequence of visual loss. Patients who suffered from glaucoma for several years were only used to refill of medications and reluctant to accept further information about their medication.
Our findings, in accordance with the study by Tang et al., showed that the education level of patients was an important factor associated with knowledge of medica-tion.12A previous study showed that only 10.9% of patients recalled their medications correctly; the main reason for such a low rate was considered to be the poor education level of the study participants.11 Another study on
glau-coma patients showed a significant difference in the ac-curacy of reporting of prescribed medications between
Table 4 Improvement of recalling of topical glaucoma medications in study participants.
With 1 drug With 2 drugs With 3 drugs Level Number (%) Number (%) Number (%) Full accuracy 59 (31.72) 11 (14.86) 4 (14.81) 3 Improve 1 score 65 (34.95) 12 (16.22) 2 (7.41) 2 Improve 2 scores NA 12 (16.22) 4 (14.81) 2 Improve 3 scores NA NA 3 (11.11) 2 Others 62 (33.33) 39 (52.70) 14 (51.85) 1 Total 186 74 27
Other included participants had less accurate responses or no improvement of score at the second test.
Table 5 Improvement of identification of topical glau-coma medications in study participants.
With 1 drug With 2 drugs With 3 drugs Level Number (%) Number (%) Number (%) Accurate twice 143 (76.88) 45 (60.81) 19 (70.37) 3 Improve 1 score 27 (14.52) 15 (20.27) 5 (15.82) 2 Improve 2 scores NA 6 (8.11) 2 (7.41) 2 Improve 3 scores NA NA 0 2 Others 16 (8.6) 8 (10.81) 1 (3.7) 1 Total 186 74 27
Other included participants had less accurate responses or no improvement of score at the second test.
Table 6 Spearman’s rank correlation between learning ability of recalling knowledge/identification about topical glaucoma medications and demographic variables.
Knowledge Identification
Gender 0.04 0.06
Age 0.35*** 0.34***
BCVA in log MAR 0.29*** 0.32***
IOP reduction 0.01 0.02 VF, mean defect 0.39*** 0.29*** Number of topical glaucoma drugs 0.21*** 0.12* Length of glaucoma, grade 0.18*** 0.19*** Education, level 0.31*** 0.29*** *Significance< 0.5; ***significance < 0.001.
populations who completed high school and those that did not.13
Most studies demonstrated that complicated glaucoma dosing regimens are related to poor persistence with treatment.13,20In contrast, two large-scale studies showed that patients on multiple ocular hypotensive eye drops had better adherence to treatment.5,21 This may be because
patients who need multiple drugs are those with difficult IOP control or with more severe glaucomatous damage. Accordingly, they may be more compliant with treatment to prevent the possible development of blindness. Howev-er, the number of glaucoma drugs did not appear to be a significant predictor of learning capacity in this study. Regarding the benefits of clinical education, all our study participants were followed up at the glaucoma clinic for at least 6 months. If the study participant did not recall or identify medication at the first test, Dr. Ko familiarized the patient about the number of drugs, their names, dosing, and associated side effects. Our study demonstrated that education imparted by the treating physician did not improve knowledge about medication in all study partici-pants. We believe that factors that affect learning ability identified in the current study would provide information for establishing future strategies to improve knowledge of glaucoma medications.
In summary, the findings of our study confirm that knowledge of glaucoma medications remains insufficient in Taiwan. The level of knowledge may be improved after a reminder by the treating physicians. Physicians in practice should encourage patients to have a better understanding about their medications, especially those who are elderly, illiterate, and have loss of visual function.
Conflicts of interest
No potential, financial and nonfinancial conflicts of interest.
Acknowledgments
This research (HCH 104-088) was supported with the grant of National Taiwan University Hospital, Hsin Chu Branch. The IRB Number (103-066-E) was approved by the institu-tion Review Board of Nainstitu-tional Taiwan University Hospital, Hsin Chu Branch.
References
1.Quigley HA. Glaucoma. Lancet 2011;377:1367e77.
2.Chan EW, Li X, Tham YC, Liao J, Wong TY, Aung T, et al. Glaucoma in Asia: regional prevalence variations and future projections. Br J Ophthalmol 2016;100:78e85.
3.Schwartz GF, Quigley HA. Adherence and persistence with glaucoma therapy. Surv Ophthalmol 2008;53(Suppl. 1): S57e68.
4.Kooner KS, AlBdoor M, Cho BJ, Adams-Huet B. Risk factors for progression to blindness in high tension primary open angle glaucoma: comparison of blind and nonblind subjects. Clin Ophthalmol 2008;2:757e62.
5.Hwang DK, Liu CJ, Pu CY, Chou YJ, Chou P. Persistence of topical glaucoma medication: a nationwide population-based cohort study in Taiwan. JAMA Ophthalmol 2014;132:1446e52. 6.Kahook MY, Noecker RJ. Evaluation of adherence to morning versus evening glaucoma medication dosing regimens. Clin Ophthalmol 2007;1:79e83.
Figure 1 Demographic and clinical variables associated with learning capacity of knowledge regarding glaucoma medications were conducted with classification tree analysis. A significant proportion of participants without learning capacity (level 1; groups A, B, E, and G) were older than 69.5 years and lower education attainment (less than 1.5).
7.Dreer LE, Girkin C, Mansberger SL. Determinants of medication adherence to topical glaucoma therapy. J Glaucoma 2012;21: 234e40.
8.Tsai JC. A comprehensive perspective on patient adherence to topical glaucoma therapy. Ophthalmology 2009;116:S30e6. 9.Sleath B, Blalock S, Covert D, Stone JL, Skinner AC, Muir K,
et al. The relationship between glaucoma medication adher-ence, eye drop technique, and visual field defect severity. Ophthalmology 2011;118:2398e402.
10.Lowe CJ, Raynor DK, Courtney EA, Purvis J, Teale C. Effects of self medication programme on knowledge of drugs and compliance with treatment in elderly patients. BMJ 1995;310: 1229e31.
11.Akici A, Kalaca S, Ugurlu MU, Toklu HZ, Iskender E, Oktay S. Patient knowledge about drugs prescribed at primary health-care facilities. Pharmacoepidemiol Drug Saf 2004;13:871e6. 12.Tang EO, Lai CS, Lee KK, Wong RS, Cheng G, Chan TY.
Rela-tionship between patients’ warfarin knowledge and anti-coagulation control. Ann Pharmacother 2003;37:34e9. 13.Kharod BV, Johnson PB, Nesti HA, Rhee DJ. Effect of written
instructions on accuracy of self-reporting medication regimen in glaucoma patients. J Glaucoma 2006;15:244e7.
14.Jaye C, Hope J, Martin IR. What do general practice patients know about their prescription medications? N Z Med J 2002; 115:U183.
15. Vilke GM, Marino A, Iskander J, Chan TC. Emergency depart-ment patient knowledge of medications. J Emerg Med 2000;19: 327e30.
16. McCormack PM, Lawlor R, Donegan C, O’Neill D, Smith S, Moroney C, et al. Knowledge and attitudes to prescribed drugs in young and elderly patients. Ir Med J 1997;90:29e30. 17. Cleary DJ, Matzke GR, Alexander AC, Joy MS. Medication
knowledge and compliance among patients receiving long-term dialysis. Am J Health Syst Pharm 1995;52:1895e900. 18. MacKean JM, Elkington AR. Compliance with treatment of
pa-tients with chronic open-angle glaucoma. Br J Ophthalmol 1983;67:46e9.
19. Boland MV, Chang DS, Frazier T, Plyler R, Friedman DS. Elec-tronic monitoring to assess adherence with once-daily glau-coma medications and risk factors for nonadherence: the automated dosing reminder study. JAMA Ophthalmol 2014; 132:838e44.
20. Olthoff CM, Schouten JS, van de Borne BW, Webers CA. Noncompliance with ocular hypotensive treatment in patients with glaucoma or ocular hypertension an evidence-based re-view. Ophthalmology 2005;112:953e61.
21. Gurwitz JH, Glynn RJ, Monane M, Everitt DE, Gilden D, Smith N, et al. Treatment for glaucoma: adherence by the elderly. Am J Public Health 1993;83:711e6.
