Socioeconomic inequalities in adherence to clinical practice guidelines and breast cancer survival: a multicentre population-based study in Spain

Abstract

Women residing in lower socioeconomic status (SES) areas have lower breast cancer survival but it is not clear how differences in the quality of care received contribute to these disparities. We compared adherence to clinical practice guidelines (CPG) for the diagnosis and treatment of breast cancer and subsequent breast cancer survival between women residing in lower versus higher SES areas. We conducted a multicentre population-based study of all new cases of invasive breast cancer in women diagnosed 2010-2014 in six Spanish provinces with population-based cancer registries (n=3206). Clinical data were extracted in the framework of the European Cancer High Resolution studies and vital status follow-up covered a minimum of 5 years. SES of the patient's residence was measured with the 2011 Spanish Deprivation Index. Adherence to CPG was measured with 16 indicators based on European and Spanish guidelines. Relative survival was modelled using flexible parametric models. There were no differences in the type of treatment received but women living in the lowest SES areas were less likely to undergo a sentinel lymph node biopsy, reconstruction after mastectomy, surgery within 30 days after pathological diagnosis and adjuvant treatment within 6 weeks after surgery. After accounting for demographic and clinical factors, women residing in lower SES areas had higher risk of death, HR=1.57 (95% CI 1.04, 2.36). Further accounting for adherence to CPG in the model, in particular having undergone a sentinel lymph node biopsy, eliminated the significant effect of SES. Despite the overall coverage of the Spanish health system, women living in more deprived areas were less likely to receive care in line with CPG and had shorter survival.