Integrated Queuing Network Models for Healthcare System Capacity Planning Under Demand Growth Uncertainty in Nigeria

National healthcare system capacity planning in Nigeria confronts simultaneous challenges of rapid population growth, epidemiological transition, workforce constraints, and persistent infrastructure deficits, creating a complex multi-dimensional planning problem that existing capacity models inadequately address. This dissertation develops integrated queuing network models for healthcare system capacity planning under demand growth uncertainty, with theoretical innovations motivated by the Nigerian healthcare system context. A systematic survey of queuing network theory, healthcare capacity planning literature, and health systems modelling approaches in low-and-middle-income countries identifies critical gaps in multi-level queuing models that capture patient pathways across primary, secondary, and tertiary care tiers. An original closed queuing network model of the multi-tier Nigerian healthcare system is formulated, with state-dependent service rates, patient routing probabilities dependent on service availability, and demand growth modelled as a non-stationary Poisson process. Approximate analytical solutions are derived using a novel decomposition approach validated against discrete event simulation. The model is calibrated using National Health Management Information System data across 12 states representing Nigeria's six geopolitical zones. Computational experiments explore optimal investment allocation across facility expansion, workforce expansion, and process improvement levers under 25-year demand growth scenarios. The dissertation establishes new theoretical results on the steady-state behaviour of multi-tier healthcare queuing networks under non-stationary demand, contributing original mathematical contributions to queuing theory alongside practical insights for Nigerian health systems planning. Keywords: queuing network, healthcare capacity, demand uncertainty, Nigeria, health systems planning