The interplay between the effects of lifetime asthma, smoking, and atopy on fixed airflow obstruction in middle age

Jennifer Perret, Shyamali C Dharmage, Melanie Matheson, David P Johns, Lyle C Gurrin, John Burgess, John Marrone, J Markos, Stephen Morrison, I Feather, Paul S Thomas, Christine F McDonald, Graham G Giles, John L Hopper, Richard Wood-Baker, Michael John Abramson, E Haydn Walters

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Rationale: The contribution by asthma to the development of fixed airflow obstruction (AO) and the nature of its effect combined with active smoking and atopy remain unclear. Objectives: To investigate the prevalence and relative influence of lifetime asthma, active smoking, and atopy on fixed AO inmiddle age. Methods: The population-based Tasmanian Longitudinal Health Study cohort born in 1961 (n?8,583) and studied with prebronchodilator spirometry in 1968 was retraced (n ? 7,312) and resurveyed (n ? 5,729 responses) from 2002 to 2005. A sample enriched for asthma and chronic bronchitis underwent a further questionnaire, pre- and post-bronchodilator spirometry (n ?1,389), skin prick testing, lung volumes, and diffusing capacity measurements. Prevalence estimates were reweighted for sampling fractions. Multiple linear and logistic regression were used to assess the relevant associations. Measurements and Main Results: Main effects and interactions between lifetimeasthma,active smoking,andatopyas theyrelatetofixedAOwere measured. The prevalence of fixed AOwas 6.0 (95 confidence interval [CI], 4.5?7.5 ). Its associationwith early-onset current clinical asthma was equivalent to a 33 pack-year history ofsmoking (odds ratio, 3.7;95 CI,1.5?9.3;P?0.005),comparedwitha24pack-yearhistoryforlate-onset current clinical asthma (odds ratio, 2.6; 95 CI, 1.03?6.5; P ? 0.042). An interaction(multiplicativeeffect)waspresentbetweenasthmaandactive smoking as it relates to the ratio of post-bronchodilator FEV1/FVC, but only among those with atopic sensitization. Conclusions: Activesmokingandcurrent clinicalasthmabothcontribute substantially to fixed AO in middle age, especially among those with atopy. The interaction between these factors provides another compelling reason for atopic individuals with current asthma who smoke to quit.
Original languageEnglish
Pages (from-to)42 - 48
Number of pages7
JournalAmerican Journal of Respiratory and Critical Care Medicine
Issue number1
Publication statusPublished - 2013

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