The short-term repeatability of histamine bronchial testing in young males. The SUS study

We have measured bronchial responsiveness (BR) to histamine on two occasion s between 5 and 24h apart, to determine if conventional and new indices of BR are repeatable. A random sample of 29 healthy male subjects with a mean age of 19 (SD 3.44) years from a larger study repeated a Yan method test of BR, recording both partial and maximal expiratory flow-volume (PEFV and ME FV) curves. From the MEFV curves log-dose slopes (LDS) for forced expiratory volume in 1 sec (FEV1), forced expiratory flow between 25% and 75% of forced vital ca pacity (FVC) (FEF25-75%), mean expiratory flow at 30% and 40% of FVC (MEF30 , MEF40), and the first moment of the spirogram (alpha (1)) truncated at 75 % and 90% of FVC were calculated. as well as the provocative dose that indu ces a 20% fall in FEV1 (PD20FEV1). From the PEFV curves LDS for alpha (1)75 % and alpha (1)90%, and MEF30 and MEF40 were derived. Apart from MEF30 and alpha (1)90% the second test was significantly lower ( P < 0.05) than the first when measuring the repeatability of spirometric in dices. whereas the LDS of the indices showed no significant change. The rep eatability expressed as intra-class correlation coefficient (ICC) was highe st for LDS FEV1 (0.87)1 second highest for LDS MEF40 (0.67) and LDS MEF30 ( 0.65). The LDS for moment indices were much less repeatable and the lowest ICC was found in all LDS indices derived from PEFV curves. Within-subject variance was not influenced by atopic status, smoking habits or recordable PD20FEV1 . As tests for bronchial hyper-responsiveness (BHR) the LDS of FEV1, MEF40 and MEF30 seem to be acceptable for use in population studies. <(c)> 2001 H ARCOURT PUBLISHERS LTD.