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X. Chong, T. Aung, D. Friedman, G. Rees, W. Wong, E. Lamoureux; A Comparative Study Between Singapore and the USA: The Magnitude and Determinants of Intentional and Unintentional Non-Adherence to Glaucoma Medication. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5830.
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Objective: To compare the magnitude and determinants of intentional and unintentional non-adherence, between glaucoma patients in Singapore and USA.
201 and 204 patients from a Singapore tertiary eye hospital and the Wilmer eye hospital (Baltimore, USA), respectively, who had been using eye-drops for at least 6 months, were recruited. Adherence and beliefs about glaucoma and its treatment were assessed using interviewer-administered surveys including the Reported Adherence to Medication Scale; the Brief Illness Perception Questionnaire; and the modified Beliefs about Medicines Questionnaire.
In Singapore, the sample had a mean age of 64.7 years old and an average treatment duration of 5.83 years, compared to a mean age of 71.7 years old and an average treatment duration of 11.3 years in the USA. In Singapore patients, 49.3% reported non-adherence of which 85.9% were unintentional; 1.0% were intentional; and 13.1% were both intentional and unintentional. Comparatively, 38.7% of the participants in the USA reported non-adherence of which 88.6% were unintentional, 3.8% were intentional and 7.6% reported both forms. In Singapore, unintentional non-adherence was associated with younger age and the perception that glaucoma has a greater effect on life while intentional non-adherence was associated with younger age; perception of having lesser personal control and that eye drops were more helpful; and lower beliefs in necessity of eye drops(p<0.05). In USA, unintentional non-adherence was associated with the perception that glaucoma has a lesser effect on life and lower beliefs in necessity of eye drops compared to the concerns about usage whereas intentional non-adherence was associated with perception of shorter timeline of glaucoma, having greater personal control and lesser beliefs in the necessity of eye drops compared to concerns about usage(p<0.05).
While the rates of intentional and non-intentional non adherence to glaucoma medication were similar in both countries, their determinants differed probably due to differences in socio-cultural and economic parameters. Patients’ beliefs in the necessity of using eye drops appear to be fundamental to effective an adherence strategy irrespective of location.
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