A scoping review of studies comparing the medication event monitoring system (MEMS) with alternative methods for measuring medication adherence

Abstract

Different methods are available for measuring medication adherence. In this paper, we conducted a scoping review to identify and summarize evidence of all studies comparing the Medication Event Monitoring System (MEMS) with alternative methods for measuring medication adherence. A literature search was performed using the open database www.iAdherence.org that includes all original studies reporting findings from the MEMS. Papers comparing methods for measuring adherence to solid oral formulations were included. Data was extracted using a standardized extraction table. A total of 117 articles fulfilled the inclusion criteria, including 251 comparisons. Most frequent comparisons were against self-report (n = 119) and pill count (n = 59). Similar outcome measures were used in 210 comparisons (84%), among which 78 used dichotomous variables (adherent or not) and 132 used continuous measures (adherence expressed as percentage). Furthermore, 32% of all comparisons did not estimate adherence over the same coverage period and 44% of all comparisons did not use a statistical method or used a suboptimal one. Only eighty-seven (35%) comparisons had similar coverage periods, similar outcome measures and optimal statistical methods. Compared to MEMS, median adherence was grossly overestimated by 17% using self-report, by 8% using pill count and by 6% using rating. In conclusion, among all comparisons of MEMS versus alternative methods for measuring adherence, only a few used adequate comparisons in terms of outcome measures, coverage periods and statistical method. Researchers should therefore use stronger methodological frameworks when comparing measurement methods and be aware that non-electronic measures could lead to overestimation of medication adherence.

How to Screen for Non-Adherence to Antihypertensive Therapy

“…However, their internal validity varies (Cronbachs’s α 0.61–0.91) and their specificity is generally below 75%. Adherence is overreported by up to 20% when compared to an objective measure [23]. These overestimates may be due to a number of reasons, for example social desirability (wanting to be seen as a ‘good’ patient).…”

“…Pill-counting overestimates non-adherence by roughly 8% when compared to data from objective electronic monitoring devices [23]. Although in theory it is a simple method, it is entirely dependent on the patient’s cooperation (bringing their pill containers to the clinic), it does not take into account any surplus medication the patient may have from previous prescriptions, and it is time consuming in a busy clinical setting [21].…”

“…Patients often take their medications outside of their home, and thus, the systems may be bulky and intrusive to the patient’s privacy [40]. Despite these limitations, EMDs are probably one of the best indirect objective methods of diagnosing non-adherence [23]. The main issue remains the high cost of the devices and the fact that device opening does not equate to ingestion of pills.…”

Improving Medication Adherence: Keep Your Eyes on the Prize

“…This is similar to the Medication Event Monitoring System (MEMS), which is considered a Bgold standard^measure of medication adherence in trial settings. 6 However, it is important to remember that it is an indirect method of measurement-opening the bottle does not equal taking the statin. It is entirely plausible, as the authors discuss, that patients receiving feedback reports were more likely to open the bottle but no more likely to take the medication.…”

“…7 A review of studies comparing the MEMS with other methods for measuring medication adherence reported that, compared to MEMS, adherence was overestimated by 17 % using self-report, by 8 % using pill count, and by 6 % using rating by a surrogate. 6 Although self-reported medication adherence may overestimate the degree of adherence, it can offer critical insight into patient-specific barriers to medication-taking. 8 For example, the intervention studied by Reddy et al would likely have a greater impact on patients whose main barrier is forgetting to take their medication than on patients whose main concern is cost-related.…”