18-yr cumulative incidence of respiratory/allergic symptoms/diseases and risk factors in the Pisa epidemiological study

Background: Few population-based studies on the effects of environmental exposure variation exist.
Aim: Assessing respiratory symptom/disease incidence related to risk factor exposure changes.
Methods: A longitudinal general population sample from two surveys (PISA2:1991-1993; PISA3:2009-2011; no. ¼ 970), aged ?20 years at baseline, completed a questionnaire on respiratory symptoms/diseases, risk factor exposure and performed spirometry. 18-year follow-up cumulative incidence of respiratory symptoms/diseases and longitudinal changes (persistence, incidence, remittance) in risk factor exposure were computed.
Results: Cumulative incidence values were: 3.2% (corresponding to a 1.8?/year incidence rate), asthma; 6.6% (3.8?/year), asthma attacks; 4.5% (2.6?/year), wheeze; 31.7% (21.0?/year), allergic rhinitis-AR; 7.6% (4.4?/year), chronic obstructive pulmonary disease-COPD; 16.1% (9.7?/year), usual cough; 18.5% (11.3?/ year), usual phlegm; 30.7% (20.1?/year), dyspnoea 1þ; 13.9% (8.3?/year), airway obstruction. The following associations emerged among respiratory symptom/disease cumulative incidence and risk factor exposure changes: a two-to-five fold higher risk for COPD, phlegm, cough, dyspnoea, asthma attacks, airway obstruction in persistent smokers; a two-to-three fold higher risk for COPD in remittent smokers; a two-fold higher risk for AR, phlegm and a four-fold higher risk for asthma in subjects with persistent occupational exposure; a two-fold higher risk for cough, phlegm, dyspnoea, AR in subjects with incident occupational exposure; a two-fold higher risk for AR, asthma attacks, COPD in subjects with incident traffic exposure.
Conclusions: Our study showed noteworthy respiratory symptom/disease incidence values and indicated that lifestyle and environmental exposure changes can differently influence onset. This information could be useful for primary prevention strategies in order to reduce the chronic disease burden in the general population.