title: Determinants of Children's Exhaled Nitric Oxide: New Insights from Quantile Regression.
abstract: While the fractional concentration of exhaled nitric oxide (FeNO) has proven useful in asthma research, its exact role in clinical care remains unclear, in part due to unexplained inter-subject heterogeneity. In this study, we assessed the hypothesis that the effects of determinants of the fractional concentration of exhaled nitric oxide (FeNO) vary with differing levels of FeNO. In a population-based cohort of 1542 school children aged 12-15 from the Southern California Children's Health Study, we used quantile regression to investigate if the relationships of asthma, socio-demographic and clinical covariates with FeNO vary across its distribution. Differences in FeNO between children with and without asthma increased steeply as FeNO increased (Estimated asthma effects (in ppb) at selected 20th, 50th and 80th percentiles of FeNO are 2.4, 6.3 and 22.2, respectively) but the difference was steeper with increasing FeNO in boys and in children with active rhinitis (p-values<0.01). Active rhinitis also showed significantly larger effects on FeNO at higher concentrations of FeNO (Estimated active rhinitis effects (in ppb) at selected 20th, 50th and 80th percentiles of FeNO are 2.1, 5.7 and 14.3, respectively). Boys and children of Asian descent had higher FeNO than girls and non-Hispanic whites; these differences were significantly larger in those with higher FeNO (p-values<0.01). In summary, application of quantile regression techniques provides new insights into the determinants of FeNO showing substantially varying effects in those with high versus low concentrations.
authors.affiliation: Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States of America; Department of Family and Preventive Medicine, University of Utah, Salt Lake City, Utah, United States of America; Veteran Affairs Salt Lake City Health Care System, Salt Lake City, Utah, United States of America.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Kiros
authors.initials: K
authors.lastname: Berhane
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Sandrah P
authors.initials: SP
authors.lastname: Eckel
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America; Department of Psychiatry, Kern Medical Center, Bakersfield, California, United States of America.
authors.forename: Muhammad T
authors.initials: MT
authors.lastname: Salam
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: William S
authors.initials: WS
authors.lastname: Linn
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Edward B
authors.initials: EB
authors.lastname: Rappaport
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Bastain
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Frank D
authors.initials: FD
authors.lastname: Gilliland
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis / Q000378:metabolism; D001944:Breath Tests; D002648:Child; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000737:chemistry*; D012220:Rhinitis / Q000175:diagnosis / Q000378:metabolism; D012307:Risk Factors
chemical_list: D009569:Nitric Oxide