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ASSOCIATION OF INDOOR NITROGEN DIOXIDE WITH RESPIRATORY SYSMPTOMS IN CHILDREN: THE EFFECT OF MEASUREMENT ERROR CORRECTION WITH MULTIPLE SURROGATES
Citation:
LI, R., E. WEITER, D. W. DOCKERY, L. M. NEAS, AND D. SPOEGELMAN. ASSOCIATION OF INDOOR NITROGEN DIOXIDE WITH RESPIRATORY SYSMPTOMS IN CHILDREN: THE EFFECT OF MEASUREMENT ERROR CORRECTION WITH MULTIPLE SURROGATES. JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY. Nature Publishing Group, London, Uk, 16(4):342-350, (2006).
Impact/Purpose:
To evaluate the effect of indoor nitrogen dioxide exposure on the annual risk of lower respiratory symptoms
Description:
In 1991, Neas et al. reported that indoor nitrogen dioxide (N02), a by-product of high-temperature combustion, was significantly associated with lower respiratory symptoms among a cohort of 1159 white children ages 7-11 years in six US cities studied from 1983-1988. For each 15 ppb increment of NO2, the multivariate adjusted odds ratio (OR) was 1.4 (95% confidence interval (CI)=[1.1,1.7]). Although indoor nitrogen dioxide concentration in the ambient air was assessed only in a subset of the children, the prevalence of lower respiratory symptoms and surrogate exposure variables were available on all of the children at the time of the indoor monitoring program. This paper evaluates the effect of indoor nitrogen dioxide exposure on the annual risk of lower respiratory symptoms by applying a regression calibration method to the 2891 children in the overall study with complete covariate and outcome data, 1137 of whom had NO2 directly measured and 1754 for whom only surrogate exposure data were available. An estimate of the indoor annual nitrogen dioxide average exposure effect (ppb) is obtained adjusted for the measurement error induced by the use of surrogate nitrogen dioxide sources, including the presence of a gas stove with or without a pilot light, the presence of a kerosene space heater, the presence of a wood stove, and the usage of stove for heating, and residential characteristics, including fan usage for kitchen ventilation and the total number of rooms in the home. After adjusting for age, gender, city, parental history of respiratory diseases and smoking inside the children's home (pack/day), a 15 ppb increment in nitrogen dioxide exposure was found to be associated with a significant 50% increased annual risk of lower respiratory symptoms (OR=1.5, 95% Cl=[1.2,1.8]). Simulation results indicated that under conditions similar to those observed in these data, the estimator is unbiased and has a coverage probability close to the nominal value. Using the methodology illustrated in this paper, all of the available data were used to obtain a 34% more precise estimate of the NO2 exposure effect on lower respiratory symptoms that was adjusted for measurement error due to using NO2 surrogates instead of directly measured NO2.
Keywords: regression calibration; measurement error; validation study; main study; nitrogen dioxide; respiratory disease.