Am. J. Respir. Crit. Care Med.,
Volume 158, Number 1, July 1998, 60-64
Cotinine Excretion as a Predictor of Peak
Flow Variability
JOACHIM
KUEHR,
THOMAS
FRISCHER,
WILFRIED
KARMAUS,
ROLF
MEINERT,
THOMAS
PRACHT,
and
WILLI
LEHNERT
University Children's Hospital, Freiburg, Germany; University Children's Hospital, Vienna, Austria; NORDIG Institute for Health Research
and Prevention, Hamburg; and University of Mainz, Institute of Medical Statistics and Documentation, Mainz, Germany
Environmental tobacco smoke (ETS) is suspected to be an important risk factor for bronchial hyperresponsiveness. In order to test the effect of ETS, we measured expiratory flow rates and urine cotinine
excretion (UCE) within a narrow time window in two consecutive years. Maternal smoking habits and
medical history were ascertained by standardized questionnaires. The percentage ratio of the amplitude over the mean (AVAM) of the diurnal peak flow rates of children (complete values from at least
five consecutive days) was calculated as an indicator of bronchial responsiveness. The association of
UCE and log10AVAM was analyzed by multiple linear regression. Complete data were available for a
sample of 417 children. The median of UCE in children of parents who smoked (3.2 ng/mg and 2.9 ng/mg creatinine, Surveys 1 and 2, respectively) was higher than the median in children of nonsmoking parents (0 ng/mg in both surveys). With increasing UCE the log10AVAM rose in the first and second surveys, as well as in the longitudinal analysis (p = 0.003). This association, however, showed up
only in boys (p = 0.0001) and not in girls (p = 0.31). Our data suggest that there is a need both for
further analysis of the gender difference and for more support of strategies against passive smoking
as far as children are concerned, since airway hyperresponsiveness is a risk factor for chronic airway
impairment.
