RT Journal Article SR Electronic T1 Determinants of change in airway reactivity over 11 years in a population study (SAPALDIA) JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP erj01886-2009 DO 10.1183/09031936.00188609 A1 I. Curjuric A1 E. Zemp A1 J. Dratva A1 U. Ackermann-Liebrich A1 P-O. Bridevaux A1 R.W. Bettschart A1 M. Brutsche A1 M. Frey A1 M.W. Gerbase A1 B. Knöpfli A1 N. Künzli A1 M. Pons A1 J. Schwartz A1 C. Schindler A1 T. Rochat YR 2010 UL http://erj.ersjournals.com/content/early/2010/06/07/09031936.00188609.abstract AB We investigated determinants of change in bronchial reactivity in SAPALDIA, a population-based cohort with wide age range (29–72 years at follow-up).The role of sex, age, atopic status, smoking and BMI on percent change in bronchial reactivity slope from baseline value was analysed in 3005 participants with methacholine tests in 1991 and 2002 and complete covariate data. Slope was defined as percentage decline in FEV1 from its maximal value per μmol methacholine.Bronchial hyper-reactivity prevalence fell from 14.3% to 12.5% during follow-up. Baseline age was non-linearly associated to change in reactivity slope: participants below age 50 years experienced a decline, those above an increase during follow-up. Atopy was not associated with change, but accentuated the age pattern (pinteraction=0.038). Smoking significantly increased slope by 21.2%, as did weight gain (2.7% increase per BMI unit). Compared to persistent smokers, quitters before baseline or during follow-up experienced a significant decrease in slope (−27.7% and −23.9%, respectively). Differing, but not statistically different age-relationships and effect sizes for smoking and BMI between sexes were found.Mean bronchial reactivity increases after age 50 years, possibly due to airway remodelling or ventilation perfusion disturbances related to cumulating lifetime exposures.