Divergent trends in the prevalence of asthma-like symptoms and asthma in a developing country: three repeated surveys between 2002 and 2016

Abstract

Introduction and objectives: There have been differences in temporal trends of asthma prevalence by geographic region and economic prosperity. The aim of this study was to assess temporal trends in asthma prevalence among young adolescents in Skopje, Republic of North Macedonia as a developing country with a low asthma prevalence.

Subjects and methods: Data were obtained from three cross-sectional surveys (2002, 2006, and 2016) of adolescents (12-15 years) from randomly selected schools in Skopje. Trends in the prevalence of asthma and asthma-like symptoms were investigated descriptively and using multiple logistic regression to adjust for potential confounding factors.

Results: The prevalence of asthma increased, although the changes were not statistically significant (2002: 1.7%; 2006: 2.0%; 2016: 2.8%; p=0.075). Statistically significant (p<0.05) reductions in wheeze prevalence over time (2002, 2006, 2016) were observed for current wheeze (8.8%, 7.2%, 5.5%), exercise-induced wheeze (14.2%, 7.9%, 1.9%), and night dry cough (16.5%, 13.5%, 9.6%). After adjustment for potential confounding factors, there was an increase in asthma likelihood by year compared to 2002 (2006: OR=1.22, 95%CI=0.67-2.22; 2016: OR=2.45, 95%CI=1.24-4.84). In the adjusted analyses, associations between year and the asthma-like symptoms confirmed the descriptive results, except for current wheeze, where statistical significance disappeared.

Conclusions: Divergent trends in prevalence with a decrease in asthma-like symptoms and an increase in physician-diagnosed asthma in Skopje during a period of 14 years were established. Improved asthma labelling and effective preventative treatment of symptoms may explain some of these changes, although changes in environment and lifestyle could not be ruled out.

Keywords: Adolescence; Asthma; Prevalence; Risk factors; Temporal trends; Wheeze.