Towards a comprehensive approach to the management and prognosis of systemic sclerosis's patients: The role of comorbidities in the SPRING-SIR registry

Objectives: The current knowledge about the role of comorbidities in systemic sclerosis (SSc) is limited. Therefore, the aim of this study was to evaluate the prevalence of comorbidities and their impact on disease activity and prognosis in the Systemic sclerosis PRogression INvestiGation (SPRING) registry. Methods: SSc patients from the SPRING registry, fulfilling the ACR/EULAR 2013 classification criteria, with complete data on baseline comorbidities were enrolled. The Charlson comorbidity index (CCI) was used to quantify the overall comorbidity burden. The disease activity was calculated using the revised EUSTAR activity index (AI). The impact of SSc features on CCI, the effect of CCI on SSc disease activity and mortality were tested with multivariable regression models. Results: Among 1910 SSc patients enrolled, 67.3 % had at least one comorbidity at baseline. The most frequent comorbidities were systemic arterial hypertension (23.7 %), osteoporosis (12.9 %) and dyslipidemia (11 %). The mean value of CCI score was 2.0 ± 1.8. When patients were grouped according to increasing levels of CCI, a clear separation in the distribution of SSc-related clinical features could be observed. Among over 900 patients with available follow-up, no association between baseline CCI and changes in disease activity was observed. Conversely, the risk of death over time was independently predicted by both CCI and AI. Conclusions: Comorbidities and disease activity independently impact on the prognosis of SSc patients. This suggests that the management of comorbidities, together with the reduction of disease activity, is fundamental to improve patient survival.