-




    j-
    -I-
    REVTE~W 672 C T. F I D 7 i A
    Subiect ref 8d
    "Association between exposure to environmental tobacco smoke
    and exacerbations of asthma in children"
    R A Chilmonczyk et al
    New England Journal of Medicine (1993), 228. 1665-1669
    lu
    In this study, conducted in a large allergy-asthma practice in
    Portland, Maine, USA, in 1992,data for 199 children aged up to 12 with
    asthma were collected on:
    (a) smoking by the parent and other members of the household (pro-.-ided
    by the parent),
    (b) cotinine (from urine provided by the child),
    (c) number of acute exacerbations of asthma in the last 12 months (from
    blind review of medical records),
    (d) lung function (from tests conducted on 145 of the 199 children),
    (e) demographic and other variables - including parental occupation and
    education, number of household members, age at diagnosis of asthma,
    child's current medication status, child's school status, and use of
    day care (provided by the parent), and
    (f) theophylline (from serum provided by 63 children)
    U1
    As expected, there was a strong relationship between urinary C)
    cotinine (ad'usted for creatinine) and exposure to ETS, *.:,--.h median CD
    C7%
    co
    BATCo document for Legal Services : Health Canada 19 October 1999

    




    levels 5.6 r.F,/ml if no hous ehold member smoked, ng/mI if mother or
    other household member~s) smoked, and 55.8 ng/ml if the mother and other
    household member(s) smoked. Using 10 ng/ml as a cut-off was found to
    discriminate quite wel-i between children with no re-:,or-_ed ETS exposure at
    home and those with some exposure.
    The main finding of the study was that there was a trend towards
    increas.ng number of ex acerbat ions of asthma and decreasing lung function
    with increas-ns ETS ex?osure whether one used parental reports or urinary
    cotinine. The increased risk of asthma exacerna:--ons was significanz
    after adjustment for maternal age and educacion level and the child's
    age, sex and day-care attendance, with children in the highest exposure
    group (mother and others smoke or >39 ng/ml urinary cotinine) having
    almost twice (1.8 and 1.7 respectively) the number of exacerbations of
    the lowest exposure group (no reported smoking a= home or <10 ng/ml
    urinary coz-nine). Although the corresponding reductions in forced
    expiratory volume in one second (FEV 1 ) were not quite statistically
    significant. significant reductions were seen for forced expiratory flow
    between 25% and 75% of vital capacity (FEF 25-75! ) and in FEV 1 adjusted
    ital capac~ty (FVC).
    for forced
    Serum theophylline levels were found to be similar in children
    prescribed tz:heophylline and exposed to smoke in the home and in children
    prescribed theophylline and not ETS exposed, suggesting that the two
    0
    groups of children followed medical advice similarly.
    CD
    CD
    Co
    CI%
    Co
    BATCo document for Legal Services: Health Canada 19 October 1999

    




    The authors em--*-as--ze ::*.-.e value of usinz urine cotinine levels as a
    marker of ETS ex-;:-=--re and conclude that t*-el-r s=udy "provides further
    evidence of an association between exposure to environmental tobacco
    smoke and pulmona:-- morbidi a'
    -:-.- in children with asthm I , and that their
    data "emphasize the need for systematic, persistent efforts to stop the
    exposure of children with as~*--=ta to environmental tobacco smoke".
    While the stud-.- '" qu--~e a reasonable one, it does have some
    limitations. Inter alia.
    (a) No data have tcen col--ac-ced on presence of respiratory disease in
    the parents or other ho--sehold members, so that the possibility of
    the association arising from cross- inf ection cannot be ruled out;
    (b) No data have been collected on smoking by the mother in pregnancy,
    so that possi7.-'-z- eff"ects of in utero and in Miyc exposure to tobacco
    smoke constitua-nzs cannoz be ruled out;
    (c) No data have been COlleczad on exposure to various allergens; and
    (d) Although data -;cere collected on severity of the underlying disease,
    no attempt was made to zake this into account in analysis. Did the
    children in the more E--S exposed group have more attacks because
    they were exposed more, or because they had more severe disease on
    average to sta=:: with?
    Despite these limitations, it is clear that the evidence relating to
    ETS and asthma dema7---s careful attention. It should be pointed out that
    not all studies have reported a relationship. For example, see the recent
    (Jri
    CD
    CD
    (DZ
    CI\
    Cc
    BATCo document for Legal Services: Health Canada 19 October 1999

    




    letter by Platts-Mills and Call (also attached) in the Journal of
    Pediatrics. A caref-.:'-- review is req--~-red. A recenzly published review by
    Ehrlich of the overall evidence is considered in my next review (673).
    F N Lee
    15.11.93
    40
    0
    C'il
    CD
    CD
    CD
    (31%
    cc
    BATCo document for Legal Services : Health Canada 19 October 1999