Adherence of Renal Transplant Recipients to Once-daily, Prolonged-Release and Twice-daily, Immediate-release Tacrolimus-based Regimens in a Real-life Setting in Sweden

Background. In this study we investigated medication adherence of kidney transplant patients (KTPs) to an immediate-release tacrolimus (IR-T) regimen and, after conversion, to a prolonged-release tacrolimus (PR-T) regimen in routine clinical practice. Methods. This was a non-interventional, observational, multicenter Swedish study. We included adult KTPs with stable graft function, remaining on IR-T or converting from IR-T to PR-T. Data were collected at baseline, and months 3, 6, and 12 post-baseline. The primary endpoint was adherence using the Basel Assessment of Adherence to Immunosuppressive Medication Scale (BAASIS). Secondary assessments included tacrolimus dose and trough levels, clinical laboratory parameters (eg, estimated glomerular filtration rate), and adverse drug reactions (ADRs). Results. Overall, data from 233 KTPs were analyzed (PR-T, n = 175; IR-T, n = 58). Mean change in PR-T dose from baseline (4.8 mg/d) to month 12 was -0.2 mg/d, and for IR-T (4.2 mg/d) was-0.4 mg/d; tacrolimus trough levels remained similar. Overall adherence was similar between baseline and month 12 in both groups (PR-T: 54.4% vs 57.0%, respectively; IR-T: 65.5% vs 69.4%); timing adherence followed a similar pattern. The probability of taking adherence improved between baseline and month 12 (odds ratio, 1.97; P =.0092) in the PR-T group only. Mean BAASIS visual analog scale score at baseline was 94.3 11.1% (PR-T) and 95.3 7.6% (IR-T), and >95% at subsequent visits. Laboratory parameters remained stable. Eight (4.6%) patients receiving PR-T (none receiving IR-T) had ADRs considered probably/possibly treatment-related. Conclusion. Disparity existed between high, patient-perceived and low, actual adherence. Overall adherence to the immunosuppressive regimen (measured by BAASIS) did not improve significantly over 12 months in stable KTPs converting to PR-T or remaining on IR-T; renal function remained stable.