Changes in income-related inequalities in cervical cancer screening during the Spanish economic crisis: a decomposition analysis

BACKGROUND: Cervical cancer is one of the most prevalent cancers, but it may be prevented by early detection. Social inequalities in the use of cytology testing have been identified in the literature. However, the degree of income-related inequality has not been quantified and determinants of inequality changes during the economic crisis remain unknown. METHODS: Using the Spanish National Health Surveys (2006–07 / 2011–12), we analyzed how income-related inequalities in the use of cervical cancer screening for women aged 25–64 changed across the economic crisis. We used corrected concentration indices (CCI) which were further decomposed in order to compute the contribution of the explanatory variables. An Oaxaca-type approach was employed to investigate the origin of changes over time. RESULTS: Our final sample consisted of 10,743 observations in 2006–07 and 6587 in 2011–12. Despite the higher prevalence of screening over time (from 73.9 to 77.9%), pro-rich inequality significantly increased (from CCI = 0.1726 to CCI = 0.1880, p < 0.001). Income was the main determinant of inequality in cervical screening, although its contribution decreased over time, as well as the contribution of the type of health insurance, mainly due to changes in elasticity. Other factors, such as nationality or the educational level, seem to have played an important role in the increase of pro-rich inequality of cytology testing. CONCLUSIONS: Reducing cervical screening inequalities would require actions focused on most vulnerable groups such as migrants, low income and low educated population. The implementation of population-based screening programs would also help to cope with income-related inequalities in cytology testing.