Complex Intervention Design and Evaluation Framework for Pharmacist-Led Antimicrobial Stewardship in Nigerian Tertiary Hospitals: A Medical Research Council Approach

Antimicrobial stewardship programs in Nigerian tertiary hospitals remain largely unstandardized, with interventions developed without systematic use of implementation science frameworks that account for contextual complexity. The United Kingdom Medical Research Council framework for complex interventions provides a rigorous methodology for developing and evaluating such programs. This study applied the Medical Research Council complex intervention framework to design, pilot, and evaluate a pharmacist-led antimicrobial stewardship program for Nigerian tertiary hospitals. The study proceeded through four Medical Research Council phases across a 36-month timeline. The development phase encompassed systematic evidence synthesis, theory of change development using expert consensus, and context mapping in six tertiary hospitals across North Central, South West, and South East Nigeria. The feasibility phase piloted the intervention in two hospitals with process evaluation embedded. The evaluation phase employed a stepped-wedge randomized controlled trial design across six hospitals to assess antibiotic use density, guideline concordance rates, and mortality attributable to multidrug-resistant organisms as primary outcomes. Implementation phase analysis examined scalability and sustainability. Piloting demonstrated that a pharmacist-led prospective audit and feedback model, embedded in existing ward round structures, was feasible and acceptable. Primary evaluation demonstrated a 27 percent reduction in defined daily doses per 100 bed-days and a 34 percent improvement in guideline concordance. The Medical Research Council framework proved essential for managing contextual variability across sites. This study provides a replicable, theoretically grounded antimicrobial stewardship model for Nigerian tertiary hospitals. Keywords: antimicrobial stewardship, Medical Research Council framework, complex intervention, pharmacist-led, Nigerian tertiary hospitals