Factors affecting UK primary-care costs of managing patients with asthma over 5 years

Objective: To determine the effect of age, disease severity and compliance on the annual primary-care cost of managing patients with asthma initially on British Thoracic Society British Guidelines on Asthma Management (BGAM) treatment steps 2/3 over 5 years. Design and setting: A modelling study performed from the perspective of the UK's National Health Service (NHS). Study participants and interventions: A data set was created comprising 4519 patients with asthma in the DIN-link database who were prescribed twice-daily inhaled corticosteroids and who were on steps 2/3 between 1 January and 31 December 1993. These patients were followed over 5 years. Methods: Asthma-related primary-care resource utilisation data obtained from the DIN-link database were stratified by patients' age, compliance and BGAM treatment step. Unit costs at 1999-2000 prices were applied to the resource use estimates to determine the mean annual cost per patient. Main outcome measures and results: High compliance with inhaled corticosteroids was not associated with a reduction in use of other primary-care resources, although the ratio of the number of prescriptions for inhaled corticosteroids to that for short-acting beta(2)-agonists increased, suggesting that patients' asthma was better controlled. Overall, the primary-care cost of managing a patient starting on steps 2/3 was found to be most strongly influenced by whether that patient moved onto steps 4/5 or continued to be managed on the same treatment step. If a patient continued to be managed at steps 2/3, costs were influenced in descending order of impact by compliance, previous BGAM step and the patient's age. Conclusions: Better compliance with inhaled corticosteroids is likely to lead to better asthma control and fewer asthma attacks. Notwithstanding this, increasing compliance is likely to increase primary-care costs. Consequently increasing healthcare expenditure may be the inevitable consequence of improving asthma control.