A Continuous Adherence Score, but Not Dichotomous BAASIS Screening, Is Associated with Graft Function in Kidney Transplant Recipients

Background/Objectives: Non-adherence to immunosuppressive medication is a principal modifiable determinant of kidney allograft survival, yet its associations with objective graft function remain inconsistent, in part because the Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) dichotomises infrequent and persistent non-adherence together. We tested whether a continuous adherence measure and psychological acceptance of illness are more closely associated with graft function than BAASIS.

Methods

Cross-sectional, single-centre study of 230 adult kidney transplant recipients; the primary analysis included 199 recipients with eGFR measured on the day of assessment and complete covariate data. Approximately 95% of recipients had received a deceased-donor and 5% a living-donor graft. Adherence was measured by BAASIS, the Adherence in Chronic Diseases Scale (ACDS), and the Adherence to Refills and Medications Scale (ARMS). Psychosocial covariates included the Acceptance of Illness Scale (AIS), Hospital Anxiety and Depression Scale—Modified (HADS-M), WHO Quality of Life—BREF (WHOQOL-BREF), Tilburg Frailty Indicator (TFI), and Mini-Mental State Examination (MMSE). The primary outcome was eGFR on the day of assessment; secondary and exploratory outcomes were serum creatinine and the individual eGFR slope reconstructed from annual archival records (n = 147). Multivariable linear regression adjusted for age, sex, time since transplantation, and psychosocial covariates was complemented by a linear mixed-effects model (158 recipients, 747 eGFR observations) and by sensitivity analyses, including adjustment for the immunosuppressive regimen.