Impact of Socioeconomic Status on Adult Patients with Asthma: A Population-Based Cohort Study from UK Primary Care

Introduction: Asthma morbidity and health-care utilization are known to exhibit a steep socioeconomic gradient. Further investigation into the modulators of this effect is required to identify potentially modifiable factors. Methods: We identified a cohort of patients with asthma from the Optimum Patient Care Research Database (OPCRD). We compared demographics, clinical variables, and health-care utilization by quintile of the UK 2011 Indices of Multiple Deprivation based on the location of the patients' general practice. Multivariable analyses were conducted using generalized linear models adjusting for year, age, and sex. We conducted subgroup analyses and interaction tests to investigate the impact of deprivation by age, sex, ethnicity, and treatment step. Results: Our analysis included 127,040 patients with asthma. Patients from the most deprived socio-economic status (SES) quintile were more likely to report uncontrolled disease (OR: 1.54, 95% CI: 1.16, 2.05) and to have an exacerbation during follow-up (OR: 1.27, 95% CI: 1.13, 1.42) than the least deprived quintile. They had higher blood eosinophils (ratio: 1.03; 95% CI: 1.00, 1.06) and decreased peak flow (ratio: 0.95, 95% CI: 0.94, 0.97) when compared to those in the least deprived quintile. The effect of deprivation on asthma control was greater among those aged over 75 years (OR = 1.81, 95% CI: 1.20, 2.73) compared to those aged less than 35 years (OR: 1.22, 95% CI: 0.85, 1.74; pinteraction=0.019). Similarly, socioeconomic disparities in exacerbations were larger among those from ethnic minority groups (OR: 1.94, 95% CI: 1.40, 2.68) than white patients (OR: 1.24, 95% CI: 1.10, 1.39; pinteraction=0.012). Conclusion: We found worse disease control and increased exacerbation rates among patients with asthma from more deprived areas. There was evidence that the magnitude of socioeconomic disparities was elevated among older patients and those from ethnic minority groups. The drivers of these differences require further exploration