Socioeconomic inequalities in health service utilisation in Spain: a population-based analysis of national health surveys data (2017–2023)

This study aimed to assess the association between socioeconomic status (SES) and healthcare service utilisation in Spain, considering explanatory factors based on Andersen’s behavioural model and examining patterns across the 2017–2023 period, including the COVID-19 pandemic. Population-based cross-sectional study using data from national health surveys conducted in Spain in 2017, 2020, and 2023, including individuals aged ≥ 15 years. Dependent variables were general practitioner (GP) visits, specialist consultations, hospital admissions, and emergency department use across public and private sectors. SES (high, medium, low) was the main explanatory variable. Predisposing, need-related, and enabling factors were included. Generalised linear models with negative binomial distribution and robust standard errors were fitted. Models included interaction terms between SES and survey year. Analyses were stratified by gender. A total of 66,193 responses were analysed (22,038 in 2017; 22,077 in 2020; 22,078 in 2023). In primary care, lower SES was associated with higher use (IRR = 1.11; 95% CI: 1.01–1.22), with higher utilisation among women (IRR = 1.21; 95% CI: 1.18–1.25) and no significant SES-by-year interaction. Specialist care use was lower among medium (IRR = 0.77; 95% CI: 0.69–0.85) and low SES groups (IRR = 0.70; 95% CI: 0.63–0.78), and higher among women (IRR = 1.23; 95% CI: 1.1–1.28), Spanish nationals (IRR = 1.13; 95% CI: 1.05–1.21), and those living with a partner. Hospital admissions were mainly driven by need, with a significant SES-by-year interaction ( p = 0.004) but no independent SES effect in 2020. Emergency care use was higher in lower SES groups in 2017 and 2020, with no differences in 2023 (interaction p = 0.013). Need-related factors showed the strongest associations across services. Compared with 2020, specialist use was higher in 2017 (IRR = 1.38; 95% CI: 1.19–1.61) and 2023 (IRR = 1.21; 95% CI: 1.02–1.42), and emergency use increased in 2023 (IRR = 1.19; 95% CI: 1.01–1.41). SES remains independently associated with healthcare utilisation beyond health need. Lower SES is associated with higher use of primary care and emergency services and lower specialist use. Socioeconomic gradients are largely stable over time, with limited variation around the COVID-19 pandemic period.