Bronchitic symptoms in Italy and Sweden - Prevalence and risk factors

As a part of the European Community BioMed 1 concerted action on chronic obstructive pulmonary disease (COPD), prevalence and risk factors for symptoms related to COPD were analysed from pooled data from studies performed in Po River Delta in Northern Italy (1988-1991) and in the province of Norrbotten in Northern Sweden (1985-1987). The Italian study sample consisted of a stratified cluster sample of 2,337 subjects aged 20-73 yrs. The Swedish sample comprised 5,698 subjects, or 86% of all people aged 35-36, 50-51, and 65-66 yrs in 1986 living in eight representative areas of the province. Both areas were, and still are, relatively minimally polluted. Questions about symptoms with similar wording were used in the analyses. The prevalence rates of sputum production and longstanding cough in Northern Sweden were 20 and 18%, respectively, while the corresponding prevalences in the Po River Delta were 16 and 13%. Also, the prevalence of chronic productive cough was higher in the Swedish area, 12%, than in the Italian area, 7%. These differences in prevalence rates between the areas were statistically significant, while wheezing was equally prevalent. The prevalence of occasional wheeze was 15% in both areas, while the prevalence of persistent wheeze was 6% in the Italian versus 4% in the Swedish. Risk-factor analyses were performed by multiple logistic regression analysis. Smoking, increasing age, family history of obstructive airway disease, and in Italy also male sex, were significant risk factors for the bronchitic symptoms and wheezing in both areas. Socioeconomic status or occupational exposure related to manual work tended to be associated with an increased risk for bronchitic symptoms. A synergistic effect on chronic productive cough was caused by smoking and a family history of obstructive airway disease. When subjects who had been diagnosed as having asthma were excluded from the analysis, the influence of smoking and increasing age generally became greater, while the role of family history of obstructive airway disease as a risk factor for the symptoms decreased.