Accuracy and concordance of measurement methods to assess non-adherence after renal transplantation - a prospective study

Abstract

Background: Non-adherence (NA) to immunosuppressants (IS) among renal transplant recipients (RTRs) is associated with higher risk of allograft rejection, graft loss, and mortality. A precise measurement of NA is indispensable, although its prevalence differs greatly depending on the respective measurement methods. The objective of this study was to assess the accuracy and concordance of different measurement methods of NA in patients after renal transplantation. Design and methods: This was a single-center prospective observational study. At baseline (T0), NA was measured via physicians' estimates (PE), self-reports (SR), and tacrolimus trough level variability (CV%) in 78 RTRs. A Visual Analogue Scale (VAS, 0-100%) was applied both for SR and PE. In addition, we used BAASIS© for SR and a 5-point Likert scale for PE. NA was measured prospectively via electronic monitoring (EM, VAICA©) during a three month period. Meanwhile, all participants received phone calls in a two week interval (T1-T6) during which SRs were given. Results: Seventy-eight RTRs participated in our study. At t0, NA rates of 6.4%, 28.6%, and 15.4% were found for PE, SR, and CV%, respectively. No correlation was found between these methods. During the study, the percentages of self-reported and electronically monitored adherence remained high, with a minimum mean of 91.2% for the strictest adherence measure (Timing Adherence ±30 min). Our results revealed a moderate to high association between SR and EM. In contrast to PE and CV%, SR significantly predicted electronically monitored adherence. Overall, a decreasing effect of electronically monitored adherence was found for both taking and timing adherence (±2 h, ±30 min) over the course of the study.

Tacrolimus Area Under the Concentration Versus Time Curve Monitoring, Using Home-Based Volumetric Absorptive Capillary Microsampling

“…missed dose, drug holiday, time deviation), and are all drugs in the regimen evaluated or only a single drug (221). Reported agreement between the different tools is thus variable, from poor to moderate and high (175,183,195,215,(222)(223)(224). A valuable and recommended approach has been to use a combination of tools for improved adherence assessment (195, 199).…”

“…This threshold has previously been associated with poor clinical outcome after renal transplantation (211). However, it must be kept in mind that no standardized threshold of tacrolimus CV has been recommended (184,222). This complicates the comparison of results between studies.…”

<p>Optimization of Electronically Monitored Non-Adherence in Highly Adherent Renal Transplant Recipients by Reducing the Dosing Frequency – A Prospective Single-Center Observational Study</p>

“…Sickness, lack of time, and impracticability of the pillbox were reasons for nonparticipation. No differences were found between Responders and Non-Responders concerning age, year of transplantation, and sex (p >0.05, see also Lieb et al 47 ).…”

“…The study procedure can be viewed in Figure 1. A more extensive study design was previously published in Lieb et al 47 Inclusion criteria were renal transplant recipients who were at least 18 years of age, received tacrolimus (Advagraf© or Prograf©) as their main immunosuppressive medication, and were at least 6 months posttransplant. Excluded were patients with insufficient German language skills, severe mental disorders, and/or cognitive impairments.…”

“…[41][42][43][44][45] Especially, a possible intervention effect caused by the use of electronics could subsequently bias the interpretation of our results. 42,44,47 It is also possible that patients' diaries were incomplete and thus electronic data were biased. Especially since a more thorough diary keeping could be associated with higher adherence 64 and thus increasing the gap between adherent and less adherent patients.…”