OBJECTIVES: Chronic Obstructive Pulmonary Disease (COPD) is a prevalent disease with a significant economic burden to the UK National Health Service (NHS). NICE recommends maintenance treatment including inhaled bronchodilator medications such as long-acting muscarinic antagonists (LAMAs); tiotropium is the most widely used LAMA in the UK. The objective of this model was to quantify the budget impact to the NHS of switching patients from tiotropium to another LAMA, compared to remaining on tiotropium. METHODS : Two matched patient groups were considered: patients who switched from tiotropium to another LAMA and patients who remained on tiotropium. The budget impact model was conducted over a 3 month time horizon, with sensitivity analyses conducted over a 12 month time horizon. Costs included were costs of medication; costs of patient identification and new inhaler training; and primary care resource use in the 3 months following inhaler switch, priced according to PSSRU estimates. The number and duration of GP visits was estimated from the CPRD; a representative primary care patient database. Clinical efficacy endpoints were not included in the model. RESULTS: Across the 3 month time horizon, patients who switched therapy incurred an increased incremental cost to the NHS of £77.10 per patient compared to patients who remained on tiotropium. Switching from tiotropium to other LAMA therapy also increased the NHS economic burden in the 12 month sensitivity analyses. Increased costs were driven by higher resource utilisation in terms of GP visits amongst switchers. CONCLUSIONS: Switching patients with COPD from tiotropium maintenance to another LAMA incurs an increased cost to the NHS. This is primarily due to a higher primary care resource use in the 3 months following switch. This finding has implications for prescribing practice including GP workload and patient willingness to switch, hence patients remaining on tiotropium are cost-saving for the UK NHS