Planning Intermittent CalciNeurin Inhibitor Controls—The piCNIc Retrospective Cohort Study

ABSTRACT Background Calcineurin inhibitors (CNIs) are essential in immunosuppressive therapy after solid organ transplantation (SOT). Their narrow therapeutic index and inter‐ and intra‐individual variability require therapeutic drug monitoring (TDM), but optimal monitoring frequency remains unclear. This retrospective observational cohort study evaluated the impact of a pharmacist‐developed protocol to standardize and reduce CNI monitoring frequency on the number of CNI measurements, the achievement of CNI TDM target, and resource utilization. Methods Data was collected retrospectively from adult liver, kidney, and lung transplant patients hospitalized between February 1 and July 31 of 2023 and 2024 at the Centre Hospitalier de l'Université de Montréal (CHUM). CNI measurements per patient per week, prescription quality and patient safety were compared before and after the protocol's implementation. Results 520 hospitalizations were included (254 pre‐ and 266 post‐intervention hospitalizations). Primary analysis showed an adjusted mean reduction of 0.9950 CNI measurements per patient per week (95% CI, 0.6398 to 1.3502; p < 0.0001), corresponding to a 14.0% decrease. Secondary analysis revealed no significant differences in achieving CNI TDM target or dose adjustments between groups. CNI‐related adverse effects were similar in both groups. Conclusion The development and implementation of a new protocol by pharmacists to standardize and reduce the frequency of CNI monitoring significantly decreased the number of CNI measurements per hospitalized patient, without compromising the achievement of CNI TDM target or patient safety. This approach highlights a valuable strategy for hospitals to manage costs effectively amidst increasing financial pressures without affecting patient outcomes.