Cigarette Smoking and Bronchial Asthma in Adults

American฀states฀ [52] .฀This฀primarily฀questionnaire-based฀study฀in฀smokers฀and฀non-smok- ers฀ with฀ a฀ medical฀ diagnosis฀ of฀ asthma฀ came฀ up฀ with฀ various฀ conclusions:฀ males฀ and฀ females฀had฀equal฀prevalence฀rates฀for฀asthma,฀but฀females฀had฀higher฀incidence฀rates฀ [52] .฀Smoking฀prevalence฀was฀high฀and฀the฀diagnosis฀was฀made฀in฀all฀age฀groups฀64.7.฀ In฀a฀Finnish฀cohort฀study฀ [168] ,฀the฀prevalence฀of฀diagnosed฀asthma฀was฀higher฀among฀ male฀ smokers฀ than฀ among฀ male฀ non-smokers,฀ whereas฀ no฀ signiicant฀ difference฀ was฀ observed฀ for฀ women.฀ Overall,฀ the฀ association฀ between฀ bronchial฀ asthma฀ and฀ cigarette฀ smoking฀is฀not฀clear-cut฀ [169,฀170] . Bronchial฀responsiveness฀to฀cigarette฀smoke฀was฀studied฀in฀98฀smokers฀by฀means฀of฀ lung฀function฀measurements฀FEV 1 ,฀MEF 75 ,฀FEF {25–75} ฀in฀parallel฀with฀the฀methacholine฀ challenge฀test.฀All฀lung฀function฀indices฀were฀decreased฀after฀just฀12฀cigarette฀smoke฀inha- lations.฀FEV 1 ฀fell฀by฀10฀and฀this฀effect฀correlated฀directly฀with฀vital฀capacity,฀pulmonary฀ status฀asthma,฀bronchitis฀and฀cigarette฀consumption,฀but฀not฀with฀methacholine฀bronchial฀ reactivity฀ [171] .฀It฀is,฀therefore,฀clear฀that฀cigarette฀smoking฀is฀a฀major฀cause฀for฀the฀prog- nosis฀of฀bronchitis,฀bronchial฀asthma฀and฀COPD. The฀comparison฀of฀increased฀bronchial฀responsiveness฀of฀smokers฀with฀that฀of฀non- smokers฀ does฀ not฀ reveal฀ consistent฀ results฀ without฀ a฀ simultaneously฀ altered฀ histamine฀ response.฀Reduced฀pulmonary฀function฀was฀observed฀in฀male฀smokers฀who฀are฀older฀than฀ 21฀years฀of฀age฀ [172] .฀Other฀studies฀have฀also฀yielded฀inconsistent฀results฀ [170,฀173] .฀One฀ study฀conducted฀in฀Boston฀ [174] ฀in฀middle-aged฀and฀elderly฀patients฀revealed฀that฀current฀ smoking฀ status฀ was฀ associated฀ with฀ allergic฀ disposition฀ based฀ on฀ the฀ determination฀ of฀ methacholine฀responsiveness.฀In฀addition,฀raised฀IgE฀levels฀and฀eosinophil฀counts฀have฀ been฀detected฀in฀smokers฀ [175] .฀The฀IgE฀concentration฀did฀not฀decline฀with฀age฀in฀smokers฀ as฀compared฀to฀non-smokers. Despite฀the฀numerous฀studies฀conducted,฀it฀is฀evident฀from฀the฀indings฀reported฀that฀no฀ unequivocal฀association฀can฀yet฀be฀demonstrated฀between฀the฀development฀of฀bronchial฀ asthma฀and฀cigarette฀smoking฀in฀adults฀because฀of฀the฀varied฀potential฀for฀bias.฀In฀children,฀ numerous฀indings฀from฀more฀recent฀studies฀indicate฀that฀the฀risk฀for฀bronchial฀asthma฀is฀ increased฀as฀a฀result฀of฀passive฀smoking.

5.4.3 Bronchial Asthma in Children

More฀ than฀ 50฀ epidemiology฀ studies฀ suggest฀ that฀ children฀ who฀ are฀ exposed฀ to฀ tobacco฀ smoke฀suffer฀increasingly฀from฀respiratory฀tract฀diseases฀ [128] .฀The฀outcome฀variables฀ studied฀in฀these฀children฀include฀respiratory฀tract฀symptoms฀such฀as฀cough฀and฀rhonchi,฀ respiratory฀tract฀infections,฀new฀occurrence฀or฀deterioration฀of฀bronchial฀asthma,฀deterio- ration฀of฀pulmonary฀function,฀bronchial฀responsiveness,฀atopy฀and฀increased฀IgE฀levels.฀ Passive฀smoking฀in฀childhood,฀particularly฀where฀the฀mother฀smokes,฀has฀been฀associated฀ with฀some฀of฀these฀symptoms฀ [154,฀176–179] ฀see฀Figs.฀ 5.5 ฀and฀ 5.6 .฀However,฀the฀pres- ence฀ of฀ external฀ confounders฀ familial,฀ socio-economic฀ and฀ environmental฀ conditions฀ means฀that฀it฀is฀dificult฀to฀establish฀a฀deinite฀causal฀relationship฀ [177] . Passive฀smoking,฀particularly฀where฀both฀parents฀are฀smokers,฀is฀associated฀with฀bron- chitic฀and฀asthmatic฀states฀in฀children฀and฀adolescents฀ [182] .฀Several฀studies฀conirm฀an฀ association฀ between฀ passive฀ smoking฀ and฀ childhood฀ obstructive฀ and฀ non-obstructive฀ airways฀disease;฀for฀the฀speciic฀medical฀diagnosis฀of฀“asthma,”฀this฀association฀is฀less฀ clear฀ [183] .฀The฀younger฀the฀children฀affected,฀the฀more฀deinite฀the฀association฀of฀passive฀ smoking฀with฀the฀bronchitic฀and฀asthmatic฀symptoms,฀as฀also฀relected฀in฀hospital฀admis- sions฀ [183–187] .฀In฀contrast฀to฀maternal฀smoking,฀paternal฀smoking฀was฀not฀found฀to฀exert฀ any฀signiicant฀effect.฀A฀tendency฀for฀colds฀to฀go฀to฀the฀chest฀and฀for฀reduced฀FEV 75 ฀and฀ FEV 85 ฀has฀been฀shown฀to฀correlate฀directly฀with฀salivary฀cotinine฀levels฀ [185] . One฀ sociomedical฀ study฀ showed฀ an฀ association฀ between฀ maternal฀ smoking฀ and฀ a฀ ฀medical฀diagnosis฀of฀asthma฀in฀the฀child฀only฀where฀the฀mothers฀had฀12฀or฀fewer฀years฀of฀ education฀ [188] . The฀use฀of฀pulmonary฀function฀measurements,฀bronchial฀hyperresponsiveness฀measure- ments฀and฀skin฀prick฀tests฀as฀atopy฀markers฀to฀permit฀an฀objective฀diagnosis฀of฀asthma฀has฀ yielded฀differing฀conclusions฀concerning฀the฀association฀between฀childhood฀asthma฀and฀ passive฀smoking฀ [155,฀178,฀179,฀182,฀185,฀189,฀190] .฀The฀majority฀of฀studies฀in฀which฀ pulmonary฀function฀has฀been฀measured฀reveal฀a฀decrease฀in฀functional฀indices฀in฀passive฀ smoking฀children.฀Two฀studies฀showed฀no฀association฀ [178,฀190] .฀The฀inluence฀of฀passive฀ smoking฀on฀skin฀prick฀test฀results฀is฀controversial฀ [188,฀191,฀192] . 5 27 55 Weeks after birth 50 100 Vmax FCR [mls] 150 200 250 Fig. 5.5 ฀฀฀Maximum฀ expiratory฀low฀at฀functional฀ residual฀capacity฀during฀the฀ irst฀year฀of฀life.฀♦฀Healthy฀ control฀group;฀■฀children฀of฀ women฀who฀smoked;฀ ▲ ฀total฀ cohort฀ [180] Asthma severity Lung function FEV1 PC20; histamine [mgml] Mother Nonsmoker Smoker Nonsmoker Smoker Bronchial responsiveness Score Mother 10 100 80 60 40 20 .03 .06 125 .25 .5 1 2 4 8 16 5 Fig. 5.6 ฀฀฀Passive฀smoking฀and฀childhood฀bronchial฀asthma.฀The฀igure฀illustrates฀asthma฀severity,฀ the฀extent฀of฀reduced฀pulmonary฀function฀and฀the฀increased฀bronchial฀responsiveness฀to฀histamine.฀ Study฀conducted฀in฀94฀children฀aged฀between฀7฀and฀17฀years฀with฀a฀history฀of฀asthma.฀In฀each฀case,฀ the฀pairs฀of฀columns฀represent฀non-smoking฀and฀smoking฀mothers฀from฀ [181]