Use of combination therapy in asthma: are they prescribed according to guidelines

Combination therapy should be prescribed to patients with moderate to severe asthma after daily long-term treatment with inhaled inhaled corticosteroids (ICS) has been tried without obtaining adequate control and it is not indicated to be used as first line treatment in asthma.

To describe the use of combination therapy for the treatment of asthma and to evaluate to which extent it is prescribed as recommended.

A cohort of 14559 new users of a combination therapy identified between January 1, 2000 and September 30, 2003 was selected from beneficiaries of the Régie de l'assurance maladie du Québec. We evaluated whether the combination therapy was prescribed according to the Canadian Asthma Guidelines. A logistic regression analysis was also performed to identify patient's and physician's characteristics associated with the adherence to the recommendations of the Canadian Asthma Guidelines for the prescription of a combination therapy.

Only 40% of users of combination therapy filled a prescription of ICS in the year preceding the initiation of the therapy and this proportion decreased by 21.8% from 2000 to 2003. Patients who received their first combination therapy in an emergency department were less likely to have used ICS previously, but patients treated by a respiratory physician and patients with co-morbidities, markers of asthma severity and markers of uncontrolled asthma were more likely to have used ICS previously.

Combination therapy has not been used according to the Canadian Asthma Guidelines in a large proportion of patients.