Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a wide range of clinical manifestations and a significant burden of comorbidities, particularly cardiovascular disease.1,2 Cardiovascular risk in SLE patients is notably higher compared to the general population, driven by both traditional and disease-specific risk factors, such as chronic inflammation and prolonged glucocorticoid use.3 The literature consistently highlights that social determinants of health, including socioeconomic deprivation, significantly influence health outcomes in various chronic diseases.4 Socioeconomic status has been linked to disparities in SLE outcomes, with lower socioeconomic status associated with higher morbidity and mortality, partly due to limited access to healthcare, lower health literacy, and increased prevalence of unhealthy behaviors.5,6

Most research on health disparities in SLE has focused on contexts with significant variations in healthcare access, such as low- and middle-income countries or regions with fragmented healthcare systems.5,7 Studies have demonstrated that, in these settings, socioeconomic deprivation exacerbates health inequities, leading to poorer outcomes among SLE patients.6,7 These findings underscore the critical role of social determinants in shaping health trajectories and highlight the need for targeted interventions to mitigate these effects.4,6

However, the impact of socioeconomic deprivation in regions with universal healthcare coverage, such as the Basque Country/Euskadi,8 in Spain, remains underexplored. The Basque Country provides a unique context due to its comprehensive public healthcare system, universal and free to access, with a widespread net of primary care and extra-hospital specialized services, interconnected with county and university hospitals, some of them with reference units for autoimmune diseases, such as Cruces University Hospital.8 Patients with SLE from all over the Basque Country can easily access to our referral unit. Besides, the small size and good communications of our country make it easy for patients to keep close contact both with primary and specialized health providers. This study aimed to investigate the impact of socioeconomic deprivation on cardiovascular risk and damage in SLE patients within a universal healthcare setting in the Basque Country, Spain.

This study aimed to investigate the influence of socioeconomic deprivation on cardiovascular risk and damage in SLE patients from the Lupus-Cruces Cohort in the Basque Country, Spain. By examining a cohort with free and universal access to primary and specialized healthcare, we sought to understand whether the well-documented associations between socioeconomic deprivation and adverse health outcomes persist in a context where healthcare accessibility is not a limiting factor.

Our results indicate no significant associations between socioeconomic deprivation and the number of cardiovascular risk factors at diagnosis or at 5 years. Additionally, there was no significant association between socioeconomic deprivation and cardiovascular damage at 5 years. Interestingly, significant variables in our models included age at diagnosis and SLEDAI-2 K score, which were consistently associated with cardiovascular risk factors both at diagnosis and at the 5-year follow-up. This highlights the critical role of disease activity and age in cardiovascular health among SLE patients.3,14

The lack of a significant association between socioeconomic deprivation and cardiovascular risk and damage is consistent with the hypothesis that the comprehensive and equitable healthcare system in the Basque Country may mitigate the effects of socioeconomic disparities4,8; however, causality cannot be inferred and alternative explanations (residual confounding, limited power) remain possible. Universal access to healthcare likely reduces barriers to receiving timely and adequate medical care, thereby leveling the playing field across different socioeconomic groups.4 This contrasts sharply with findings from studies conducted in regions with less equitable healthcare systems, such as the United States, where socioeconomic deprivation significantly exacerbates health disparities.2,5–7

Other factor that may influence our findings in that the socioeconomic the B-SDI might capture deprivation differently compared to indices used in other studies.15 The specific components of this index, such as unemployment rates and educational attainment, may not directly influence health outcomes in the same way across different regions.10 Additionally, the relatively small sample size and the potential homogeneity within the Basque population could have limited the variability needed to detect significant differences.

Our study benefits from several methodological strengths that enhance the credibility and relevance of our findings. First, the longitudinal design allowed us to capture the evolution of cardiovascular risk and damage over time, providing a dynamic view of disease progression in SLE patients. The use of the Basque Socioeconomic Deprivation Index,10 tailored to the specific context of the Basque Country, enabled precise measurement of socioeconomic status, reflecting local social and economic conditions more accurately than broader indices.16 Furthermore, the incorporation of multilevel generalized linear mixed models facilitated a robust analysis by accounting for the hierarchical structure of the data and controlling for both individual-level and contextual variables. This comprehensive approach ensured that we could isolate the impact of socioeconomic deprivation on cardiovascular outcomes while considering a range of relevant clinical and demographic factors. Finally, our study's setting within a universal healthcare system offers unique insights into how equitable access to healthcare can influence health outcomes, adding a valuable dimension to the existing literature on health disparities.4–6,8,16

However, our study has also some limitations. This was a fixed, consecutive cohort with no a priori sample-size calculation; analyses are therefore precision-based, and the study was underpowered to detect small-to-moderate effects, as reflected by wide confidence intervals. Power was especially limited for key subgroups (e.g., men, migrants) and for finer deprivation strata, which restricts generalizability. BMI was not systematically recorded and could not be reliably retrieved; its omission may confound estimates, so future studies should include adiposity measures. Socioeconomic exposure was measured with the B-SDI, an area-level composite that includes “recipients of income support” but not individual/household income (nor personal education or occupation); thus, residual socioeconomic status confounding and non-differential exposure misclassification (likely biasing toward the null) are possible. The cohort’s relatively young age yielded few cardiovascular damage events over five years; we complemented event outcomes with a count of cardiovascular risk factors to capture earlier risk burden, yet modest associations may remain undetected. Finally, the observational design precludes causal inference; replication in larger, multicenter cohorts with longer follow-up, additional individual-level socioeconomic status dimensions, and in health systems with different financing models is warranted.6

The findings of this study have important implications for clinical practice and public health. They suggest that in regions with universal healthcare coverage, socioeconomic deprivation may not be a primary determinant of cardiovascular outcomes in SLE patients. This highlights the potential of comprehensive healthcare systems to mitigate health disparities and improve outcomes for disadvantaged populations, reinforcing the role of public universal health systems in the construction of more advanced and fair societies, in a time when health provisioning is being considered as a privilege and an opportunity for business in many parts of the world.4,8,16

In conclusion, in our cohort cared for within a universal healthcare system, socioeconomic deprivation was not associated with cardiovascular risk factors or damage over five years. These descriptive findings do not establish causality but are consistent with the hypothesis that universal access may mitigate socioeconomic gradients. Replication in larger, multicenter cohorts and other health-system contexts is needed.

Informed consent was obtained from all subjects involved in the study.

This study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Research Ethics Committee of Hospital Universitario de Cruces (Spain). Ethics Committee code: E08/35.

G. Ruiz-Irastorza was supported by the Department of Education of the Basque Government, research grant IT 1512-22. H. Hernandez-Negrin was supported by Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Junta de Andalucía-Sevilla (Spain), research grant PREDOC-00826.

The authors declare no conflict of interest.

The datasets generated during the present study are not publicly available due to ethical or privacy restrictions but may be requested for reasonable reasons from the author for correspondence.