Validation of a single concentration inhalation provocation test (SCIPT) in children

Abstract

Background:A new method to assess bronchial responsiveness (BR) using a single concentration methacholine has already been validated in adults with asthma1. Since the geometrical dimensions of the airways in children are different, and deposition of the inhaled aerosol also differs in children, results from studies in adults cannot simply be extrapolated to children.Aim of the study:validation of a single-concentration inhalation provocation method in children.Methods:Twenty-three subjects performed three methacholine inhalation challenge tests. The first two challenges according to method A: doubling doses, beginning with 0.03 mg to a maximum of 1.8 mg (maximal cumulated dose 3.6 mg), were administered with the Jeager Masterscope, Aerosol Provocation System (APS), medic aid sidestream nebulizer. The third challenge according method B: doubling doses, beginning with 0.002mg to a maximum of 1.8mg (maximal cumulated dose 3.5 mg), were administered with a Devillbiss 646 nebulizer. The degree of BR is expressed as a PD20. A difference of <1,5 dose step is assumed to be due to intra individual variation.Results:I.C.C. between method A and B is 0.80 and between both tests according method A 0.91. Comparing challenges 1 and 2, and 1 and 3 showed good agreement according to Bland and Altman.2Conclusion:This single concentration method is an accurate method of measuring BR in children.