Decomposition of socioeconomic inequality in COVID-19 mortality in Iran: A retrospective cohort study

This study aimed to investigate the relationship between socioeconomic status and COVID-19 mortality in Iran. We performed a retrospective cohort study on data from the hospitalised COVID-19 patients in Qazvin. We collected data on education, self-reported socioeconomic status, and location of residence as a proxy for socioeconomic status (SES). We applied the Blinder-Oaxaca decomposition approach to assess the role of socioeconomic inequality in COVID-19 mortality and determine the main contributors to the observed inequality. Overall, 941 patients (48.96%) had low SES, while only 24.87% (n = 478) were classified in the high SES category. The mortality rate was significantly higher in the low SES group, and we spotted a 17.13% gap in COVID-19 mortality between the high and low SES patients (p < 0.001). Age was the main contributor to the observed inequality, responsible for 6.91% of the gap (p < 0.001). Having co-morbidities (1.53%) and longer length of stay (LOS) in hospitals (0.95%) in the low SES group were other main determinants of the inequality in COVID-19 mortality (p < 0.05). In the unexplained part of our model, the effect of increased age (10.61%) and a positive RT-PCR test result (3.43%) were more substantial in the low SES group compared to the high SES patients (p < 0.05). The low SES people had an increased risk of getting COVID-19, and the disease has been more severe and fatal among them. Increased age, co-morbidities, and LOS were identified as the main drivers of this inequality.