Adherence
nonadherence
Adherence was measured using drug concentrations in blood sampled with a DBS and measured with UHPLC-MS/MS. Sampling of blood was always combined with a blood pressure measurement at the same time. Measured drug concentrations were either reported as positive, present in blood, or negative, absent in blood. To minimize false-negative outcomes, only undetected AHDs were reported as negative. The intra-patient variability of AHD concentrations in blood is high, and therefore, trough levels could not be used as a cut-off for nonadherence [Patients were categorized as nonadherent if all measured AHDs were reported as negative, partially nonadherent if one or more AHDs were reported as negative but at least one AHD was reported as positive, and adherent if all measured AHDs were reported as positive. The adherence data were converted into a binary variable by combining total nonadherent and partially nonadherent together.