Socioeconomic inequalities in asthma and respiratory symptoms in a high-income country: changes from 1996 to 2016

Abstract

Objective: Low socioeconomic status based both on educational level and income has been associated with asthma and respiratory symptoms, but changes over time in these associations have rarely been studied. The aim was to study the associations between educational or income inequality and asthma and respiratory symptoms among women and men over a 20-year period in northern Sweden. Methods: The study was performed within the Obstructive Lung disease in Northern Sweden (OLIN) research program. Mailed questionnaire surveys were administered to a random sample of adults (20-69 years of age) living in Sweden, in 1996, 2006 and 2016. Data on educational level and income were collected from the national integrated database for labor market research. Results: The educational inequality associated with asthma and asthmatic wheeze tended to decrease from 1996 to 2016, while it increased for productive cough, the latter among men not among women. The income inequality decreased for productive cough, especially for women, while no clear overall trends were found for asthmatic wheeze and asthma, apart from a decrease in income inequality regarding asthma among men. Conclusion: The patterns for socioeconomic inequality differed for asthma and wheeze compared to productive cough, and the results emphasize that education and income do not mirror the same aspects of socioeconomic inequality in a high-income country. Our findings are important for decision makers, not the least on a political level, as reduced inequality, e.g. through education, could lead to reduced morbidity.

Keywords:

• Asthma
• Respiratory symptoms
• Socioeconomic status
• Socioeconomic inequality
• Epidemiology

Acknowledgements

Zandra Lundgren, Bo Selinder and Tessa Pohjanen are acknowledged for computerization of data.

Disclosure of interest

The authors report no conflict of interest.

Authors’ contributions

CS carried out the statistical analyses and drafted the manuscript. AL, HB, and ER contributed with design of the study. All authors contributed with interpretation of analyses, important intellectual content and critical revision of the manuscript and approved the final version.

Data availability statement

Data are available upon reasonable request from the corresponding author.

Additional information

Funding

Financial support from NordForsk (an organization under the Nordic Council of Ministers facilitating Nordic cooperation on research), the Swedish Heart-Lung Foundation, the Swedish Asthma and Allergy Association, VISARE NORR (Northern county councils’ regional federation), a regional agreement between Umeå University and Västerbotten County Council (Avtal om läkarutbildning och forskning, ALF), and Norrbotten County Council are gratefully acknowledged. The work was supported by Astma- och Allergiförbundet; Norrbottens Läns Landsting.