Diagnostic accuracy of measurement methods to assess non-adherence to immunosuppressive drugs in kidney transplant recipients.

Valid assessment of immunosuppressive therapy non-adherence (NAH) is vital: NAH is associated with negative transplantation outcomes. We studied the diagnostic accuracy of assay, patient self-reports and clinicians' collateral reports and composite adherence scores using electronic monitoring (EM) as a reference standard. This cross-sectional study included a convenience sample of 249 adult kidney transplant recipients (Ktx) (female: 43.4%; mean age 53.6 [SD: 12.7], median 7 years [IQR: 9 years] post-Ktx). NAH was assessed using EM over 3 months (i.e. reference standard), assays of cyclosporine, tacrolimus, mycophenolat-mofetil, patients' self-reports and clinicians' collateral reports. The constructed composite adherence score included assay, self-reports and collateral reports. NAH's prevalence across the measurement methods was EM: 17.3%; assay: 33% (cyclosporine: 25.8%; tacrolimus: 35.1%; mycophenolat-mofetil: 40.2%); self-report: 12.4%; collateral reports: 24.9% and composite adherence score: 38.9%, respectively. The composite adherence score and collateral reports showed the highest and lowest sensitivities to NAH (72.1% and 15.8%, respectively). Specificity was highest for collateral reports of at least three clinicians (93.1%). Likelihood ratio of a positive test was 2.74 for composite adherence score. No measures showed high sensitivity alongside high specificity. Combining measures increased diagnostic accuracy, indicating the relevance of combined measures for clinical and research purposes.

Prevalence and risk factors of non-adherence with immunosuppressive medication in kidney transplant patients.

Non-adherence with immunosuppressive regimen is a major risk factor for poor outcome after kidney transplantation. Identifying patients at risk for non-adherence requires understanding the risk factors for non-adherence. This prospective study included a convenience sample of 249 adult kidney transplant patients >1 year post-transplant. Non-adherence was monitored electronically using MEMS(R). Selected socio-economic, therapy-, patient-, condition- and healthcare team-related risk factors for non-adherence were assessed. Period prevalences were expressed as the percent of prescribed doses taken (taking adherence), the percent of correctly dosed days (dosing adherence), the percentage of inter-dose intervals not exceeding 25% of the prescribed interval (timing adherence), and the number of drug holidays per 100 days (no intake for > 48 h if once daily or for > 24 h if twice daily intake). Testing occurred by simple mixed logistic regression analysis. Factors significant after correction for multiple testing were entered into a multiple logistic regression model. Mean taking, dosing, timing adherence, and drug holidays were 98%, 96%, 93%, and 1.1 days, respectively. Non-adherence was associated with lower self-efficacy, higher self-reported non-adherence, no pillbox usage, and male gender. Adherence declined between Monday and Sunday. This study provides a framework for identifying patients at risk for non-adherence and for developing adherence-enhancing interventions.