The aim of this population-based longitudinal study was to examine the associations between socioeconomic status (SES) and anti-asthmatic treatment with inhaled corticosteroids (ICS) among young Danish adult asthmatics, and to investigate whether these associations were consistent over time.
We extracted data on prescription drug use, education, and income in 97 665 users of anti-asthmatic drugs, aged 18-44 years, identified in Statistics Denmark during 1997-2005. Individual information on education and income was used as measures of SES. Education was categorised into basic school/high school, vocational training, and higher education, and income was categorised into low, middle, and high income. Associations between ICS use and SES were estimated by logistic regression models.
High levels of education and income were independently associated with ICS use, education demonstrating the strongest association. Using basic school/high school and low income as baselines, the adjusted odds ratios (ORs) of ICS use for higher education were 1.46 (95% CI 1.40-1.51) and 1.10 (95% CI 1.06-1.14) for high income. Higher education was a nearly constant factor associated with ICS use throughout the observation period, but high income did not demonstrate any association before 2001 with increasing ORs observed each year hereafter. All associations became more pronounced when restricting to 35-44 year-olds.
High levels of SES were positively associated with ICS use in young adult asthmatics. To encourage ICS use, special attention should be paid to asthmatics with low educational level and low income. Further studies are needed to elucidate underlying mechanisms for this socioeconomic inequality.