Asthma medication - persistence with adrenergics, steroids and combination products over a 5-year period.

Background: Many patients with asthma underuse steroids for inhalation. This has been identified as a main cause of therapy failure and of excess health care utilization. Objective: To elucidate the medication persistence of patients using asthma drugs, how patients combine the drugs over time and whether medication persistence was influenced by patients switching to combination products. Methods: Individual patients' drug acquisition data were obtained from a pharmacy record database for the period 2000-2004. A patient was considered to have satisfactory medication possession ratio (MPR) if the medication supplies covered ≥80% of the prescribed treatment. Drug use profiles were constructed as graphs for each patient, showing the date of each refill and the time period covered by the dispensed drugs. From the graphs the combination of drugs, the continuity of the therapy over time and the MPR for each patient could be determined. Results: Of 1812 patients with asthma drugs in the database, 815 fulfilled the inclusion criteria. The percentage of patients with satisfactory MPR was low (11-27%), but significantly higher among patients using combination products than among those using steroids. For patients who switched from adrenergics plus steroids in two inhalers to combination products in one inhaler, the number of patients with satisfactory MPR was significantly increased. Conclusion: Satisfactory MPR was low for all types of asthma drugs. More patients had satisfactory MPR with combination products in one inhaler than with adrenergics and steroids in two separate inhalers. Asthma drug-delivery is important and combination products of the two ingredients could therefore improve asthma therapy.