From the Authors

From the authors:

The letter from J. Knox and D. Jarvis about the outcome of the dosimeter quality control programme for the measurement of bronchial hyperresponsiveness in the European Community Respiratory Health Survey (ECRHS) II is reassuring. Although our initial worries about excessive variation between Mefar^TM dosimeter (Mefar^TM, Brescia, Italy) driving pressures from our own observations 1 do not seem to have been confirmed in most of the ECRHS centres, the value of the quality control programme does seem to have been validated.

Although the variations in driving pressures reported to the Coordinating Centre were not as great as we had observed with a number of dosimeters from a small number of international centres, the range of mean pressures quoted still seems to be outside the manufacturer's specifications of 180 (±5%) kPa. We made a proposal to the ECHRS II for our laboratory to act as a “neutral” and a confidence reference agency to collect and collate the calibration information obtained by study centres following the instructions we provided on our website. For the sake of complete objectivity, it is perhaps a pity that this did not occur. Even so, we are pleased that our work to highlight a potential difficulty with the Mefar^TM dosimeter has been very worthwhile, and will certainly have even greater confidence in the data generated by ECHRS II.