AN ASSESSMENT OF METHACHOLINE INHALATION TESTS IN ELDERLY ASTHMATICS

Abstract

We have assessed the feasibility and value of measuring nonspecific bronchial responsiveness to methacholine in investigation of asthma in the elderly. Results from duplicated tests in 20 subjects aged 65–82 years were expressed as dose provoking a 20% decrement in 1 second forced expiratory volume (PD ₂₀ .FEV ₁ ) or peak expiratory flow (PD ₂₀ .PEF). Repeatability for PD ₂₀ .FEV ₁ was satisfactory but less good than in younger subjects, 95% confidence limits being 0.39–2.57 and 0.52–1.91, respectively, × initial PD ₂₀ . For PD ₂₀ .PEF, confidence limits were wider (0.26–3.91 × initial PD ₂₀ ) but multiple PEF measurements were better tolerated than those of FEV ₁ , which commonly caused fatigue and dizziness. PD ₂₀ . FEV ₁ and PD ₂₀ .PEF correlated closely (r=0.95, P <0.0001) and both predicted bronchodilatation following a 6-week course of inhaled corticosteroid and beta agonist. This was not predicted by the response to a single dose of beta agonist. We conclude that measurement of bronchial responsiveness is feasible and clinically valuable in elderly subjects.