Age-Dependent Deterioration of Peak Inspiratory Flow with Two Kinds of Dry Powder Corticosteroid Inhalers (DiskusRand TurbuhalerR) and Relationships with Asthma Control

Abstract

Inhaled corticosteroid (ICS) therapy has improved the quality of life (QOL) for many asthmatics and reduced mortality rates associated with asthma. However, some patients do not obtain therapeutic benefit despite satisfactory adherence. To determine whether asthmatic patients were using ICS devices appropriately, and to clarify relationships between these results and QOL. We studied 100 adult asthmatics, divided into two groups: 50 patients consecutively registered as using Diskus (fluticasone; D-group) and 50 consecutively registered as using Turbuhaler (budesonide; T-group). We measured peak inspiratory flows (PIFs) using the In-Check Dial device. Subjects also completed the Asthma Control Test for evaluation of QOL. In the D-group, no patients showed PIF below the optimal range (30-90 L/min), whereas 52% of patients had PIF≥91 L/min. In the T-group, 6% of patients showed PIF over the optimal range (60-90 L/min), and 44% had PIF≤59 L/min. When patients in the T-group were required to deliberately make a maximal inhalation, 14% still had PIF≤59 L/min. The proportion of patients with poor control was significantly greater in the T-group than in the D-group. According to univariate logistic regression analyses, low PIF tended to be associated with poor asthma control in the T-group. No significant correlation was found between PIF and age in the D-group, but PIF decreased significantly with age in the T-group. Appropriate measures for patients in whom PIF has been judged as lower than optimal include adequate education for inhalation and/or changing to a different inhalation device. These measures should be kept in mind for elderly asthma patients in particular, where appropriate selection of a corticosteroid inhalation device in the early stages of therapy would also be important.