Accuracy of Patient-reported Adherence to Glaucoma Medications on a Visual Analog Scale Compared With Electronic Monitors

Abstract

Purpose Glaucoma medications can reduce intraocular pressure and improve clinical outcomes when patients adhere to their medication regimen. Providers often ask glaucoma patients to self-report their adherence, but the accuracy of this self-report method has received little scientific attention. Our purpose was to compare a self-report medication adherence measure with adherence data collected from Medication Event Monitoring Systems (MEMS) electronic monitors. Additionally, we sought to identify which patient characteristics were associated with over-reporting adherence on the self-reported measure. Methods English-speaking adult glaucoma patients were recruited for this observational cohort study from six ophthalmology practices. Patients were interviewed immediately after a baseline medical visit and were given MEMS containers, which were used to record adherence over a 60-day period. MEMS data were used to calculate percent adherence, which measured the percentage of the prescribed number of doses taken, and timing adherence, which assessed the percent doses taken on time. Patients self-reported adherence to their glaucoma medications on a visual analog scale (VAS) approximately 60 days following the baseline visit. Bivariate analyses and logistic regressions were used to analyze the data. Self-reported medication adherence on the VAS was plotted against MEMS adherence to illustrate the level of discrepancy between self-reported and electronically-monitored adherence. Findings The analyses included 240 patients who returned their MEMS containers and who self-reported medication adherence at the 60-day follow-up visit. When compared with MEMS-measured percent adherence, 31% of patients (n=75) over-estimated their adherence on the VAS. When compared with MEMS-measured timing adherence, 74% (n=177) of patients over-estimated their adherence on the VAS. For the MEMS-measured percent adherence, logistic regression revealed that patients who were newly prescribed glaucoma medications were significantly more likely to over-report adherence on the VAS (OR=3.07, 95% CI: 1.22, 7.75). For the MEMS–measured timing adherence, being male (chi-square=6.78, p=0.009) and being prescribed glaucoma medications dosed multiple times daily (chi-square =4.02, p=0.045) were significantly associated with patients over-reporting adherence on the VAS. However, only male gender remained a significant predictor of over-reporting adherence in the logistic regression, (OR=4.05, 95% CI: 1.73, 9.47). Implications Many glaucoma patients, especially new patients, over-estimated their medication adherence. Because patients were likely to over-report percent doses taken and timing adherence, providers may want to ask patients additional questions about when they take their glaucoma medications in order to potentially detect issues with taking glaucoma medications on time.

Diabetes Management and Healthcare Resource Use When Intensifying from Basal Insulin to Basal-Bolus: A Survey of Type 2 Diabetes Patients

“…It is unclear why respondents in this group were predominantly female and how this may have affected the results. Previous research has found that men over-report glaucoma medication adherence in their self-reports compared to adherence timing data collected from electronic monitors [ 23 ]. It is possible that there are gender differences in self-reported adherence to insulin, though additional research is warranted.…”

Medication adherence in patients with ocular hypertension or glaucoma

“…These were used with both twice-daily and fourtimes-daily topical IOP-lowering medications; there was no Hawthorne effect because patients were supplied bottles and were unaware of being monitored [36,37]. Since then, a variety of electronic tools have been developed and used to assess adherence to eyedrops [54,55]. Unfortunately, these tools are primarily used in research and are not widely available for use in clinical practice.…”

“…A variety of clinical studies have used a Medication Event Monitoring Systems (MEMS) device. In these scenarios, the eyedrop bottle is placed with a MEMS device that tracks when a patient opens the outer bottle containing the eyedrop bottle [10,55]. One problem with this approach to date has been the short-term nature of the assessment; studies generally range from 1 to 3 months.…”

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“…Self-reported adherence is known to be over-estimated compared to electronically monitored data. 13 However, using a validated instrument to measure self-reported adherence is still a valuable tool for estimating adherence. Refill adherence is a less costly method of assessing adherence than electronic monitoring and is not subject to the Hawthorne effect or to the bias of self-report.…”