Use of an electronic medication monitoring device to estimate medication adherence in kidney transplant patients

Electronic medication monitoring devices (EMD) have been used as a gold standard for assessing medication adherence. We used a wireless EMD (SimpleMed+), assessed its usability in patients after kidney transplantation (KTx), evaluated adherence, and analyzed concordance with other adherence measures. Fifty-five patients (53% female, mean age 46 years) at least 6 months after KTx agreed to use the EMD over a period of 8 weeks. Self-reported adherence was measured with the BAASIS, and immunosuppressant trough level variability was assessed prior to and again during the study period. Fourteen patients stopped using the EMD or were low users (<70%). These non-completers reported that using the EMD would interfere with their daily activities. Taking-adherence of the completers was high with 98.3% (1.9) over the entire study period. Timing-adherence was somewhat lower (94.6% +/- 7.9) and decreased during the second half of the study. We found statistically significant correlations between EMD results and self-reported adherence with moderate effect sizes, but no significant association with trough level variability. The low usage of the EMD supports the need to assess the practicability of an EMD before applying it in research and clinical routine. Taking- and timing-adherence of KTx patients using the EMD was satisfactory. Self-reported adherence might be a good enough estimate of medication adherence.