Effect of age on the conformity rate to short-acting beta-agonist use criteria in asthma.

STUDY OBJECTIVES: Assess compliance to asthma guidelines and influence of age concerning inhaled short-acting beta2-agonist (SABA) utilization in 5 to 45-year-old asthmatic subjects in the province of Quebec.

DESIGN: Population-based retrospective drug utilization review using a computerized database of claims submitted to a private prescription drug insurance plan.

PATIENTS: Subjects who received at least one outpatient prescription of SABA (age range, 5 to 45 years) for the treatment of asthma between January 1996 and December 1997.

MEASUREMENTS: Percentages of patients whose use was appropriate according to the criteria regarding the average daily dose of SABA. Use was considered appropriate if the consumption rate corresponded to a maximum of two puffs per day (Salbutamol equivalent) in subjects who did or did not use inhaled corticosteroids (ICS) at an estimated maximum dose of 800 mcg/day of Beclomethasone (BDP) equivalent for the 5 to 11-year-olds and 1000 mcg/day for the 12 to 45-year-olds.

RESULTS: In 1996, use was found to be appropriate for 74.4% of the 394 patients who received an SABA without ICS as compared with 70.7% for 593 patients in 1997. If we consider those who received an ICS at low to moderate doses, appropriate use was found for 51% of the 375 patients in 1996 and 57.6% for 254 patients in 1997. If we exclude patients who did not renew their SABA, appropriate use drops to 46.3% for 1996 and 34.3% for 1997 for the group who receive SABA without ICS (29.4% and 37.6%, respectively, for those with ICS). There is a relationship between age and appropriateness; the percentage of appropriateness was higher for the younger ones (5 to 14-year-old group; 83% in 1996 and 86% in 1997 for the patients who received a SABA without IS and 58.5% in 1996 and 73% in 1997 for the patients who received a SABA using ICS (p < 0.05).

CONCLUSION: Our results indicate that adherence to asthma guidelines concerning SABA is poor. SABA are still overused, particularly among ICS users, which might be explained by undertreatment or poor compliance. Appropriate SABA use was significantly more common among younger groups (p < 0.05). This can be explained by better treatment in that age group, better compliance or less severe asthma.