Background: Frailty is characterized as a state of increased vulnerability stemming from the degradation of homeostatic mechanisms, resulting in a diminished capacity to respond effectively to biological stressors. One approach to operationalizing frailty is through a frailty index (FI), which conceptualizes frailty as a decline of physiologic reserve arising from the accumulation of health deficits across multiple systems. Health deficits in SLE may occur due to the disease, its treatment, other comorbidities or aging. Frailty in SLE has been associated with compromised physical and cognitive functions, increased rates of hospitalizations and infections, the presence of organ damage, elevated mortality risks and a deterioration in quality of life. An important consideration is the potentially reversible nature of frailty; consequently, early recognition and intervention can significantly enhance the prognosis for affected individuals. The Systemic Lupus International Collaborating Clinics (SLICC) inception cohort developed the SLICC-FI for application in SLE patients; however, external validation studies for this index remain limited and a validated Brazilian Portuguese version is not yet available.

Objectives: To externally validate the SLICC-FI in a prevalent cohort of Brazilian individuals with long-standing SLE, using a version translated and adapted into Brazilian-Portuguese (SLICC-FI Pt-BR).

Methods: This is a cross-sectional, test-retest study, which evaluated measurement properties of the SLICC-FI Pt-BR according to COSMIN and OMERACT recommendations. The final sample included 121 patients ≥18 years old that met classification SLICC/2012 and/or ACR/EULAR 2019 criteria for SLE. Reliability was tested using the type 2.1 intraclass correlation coefficient (ICC2.1), with 95% Confidence interval (95%CI), and standard error of measurement (SEM) with minimum detectable difference (MDD). The analysis of construct validity followed specific hypotheses considering correlation/association of SLICC-FI Pt-BR (continuous and categorized as frail - SLICC-FI>0.21 vs. non-frail SLICC-FI ≤0.21) with Charlson Comorbidity Index (CCI); disease activity (SLEDAI-2k and PGA) and the definitions of remission (DORIS) and low disease activity (LLDAS); SLICC-Damage Index (SDI); health-related quality of life (HRQoL), measured using SF36 (Mental and Physical components – MCo and PCo); and handgrip strength (HGS); using Spearman, Mann Whitney, and Fisher/chi-square tests.

Results: The mean (SD) age was 44.3 (12.4) years, 93.4% female, 28.9% was classified as frail. SLICC-FI Pt-BR inter-rater reliability was excellent (ICC2.1 0.942, 95%CI 0.821,0.948) and intra-rater was good (ICC2.1 0.869, 95%CI 0.235,0.806). There was no significant correlation/association between SLICC-FI Pt-BR and Charlson Comorbidity Index. A positive correlation was found between SLICC-FI Pt-BR and disease activity: SLEDAI-2k (rho 0.570; 95%CI 0.435,0.679) and PGA (rho 0.604, 95%CI 0.477,0.707). Disease activity was associated with frailty: SLEDAI-2k median (IQR): frail 8.0 (4.0–12.0) vs. non-frail 2.0 (0.0–6.0); p<0.001 and PGA median (IQR): frail 2.0 (1.5–2.5) vs. non-frail 0.0 (0.0–1.8); p<0.001. Remission by DORIS (frail 8.6% vs. non-frail 46.5%) and LLDAS (frail 8.6% vs. non-frail 48.8%) were more frequent in non-frail patients (p<0.001 for both). The weak positive correlation between SLICC-FI Pt-BR and SDI was significant (rho 0.338; IC95% 0.169–0.487). The frequency of damage was higher among frail individuals [SDI median (IQR): frail 2.0 (1.0–3.0) vs non-frail 1.0 (0.0–2.0); p=0.016]. Negative correlations were identified between SLICC-FI Pt-BR with HRQoL (SF-36 MCo: rho -0.375; IC95% -0.519; -0.211 and PCo: rho -0.728; 95%CI -0.803, -0.632); and low HGS (rho -0.281, 95%CI -0.438, -0.108), indicating a lower HRQoL and HGS in frail individuals.

Conclusion: The present study validated the SLICC-FI in a population distinct from the original cohort, specifically among patients with long-standing lupus from an underdeveloped country. The findings demonstrated that the SLICC-FI Pt-BR is a reliable and valid instrument for assessing frailty in SLE patients. Evaluating frailty using the SLICC-FI is crucial for managing a disabling chronic disease like SLE, as frailty is potentially reversible, and its improvement may positively impact survival and HRQoL. Future longitudinal studies are needed to validate the responsiveness and prognostic properties of SLICC-FI Pt-BR.

REFERENCES: [1] Legge A, Kirkland S, Rockwood K, Andreou P, Bae SC, Gordon C, et al. Construction of a Frailty Index as a Novel Health Measure in Systemic Lupus Erythematosus. The Journal of Rheumatology. 2020;47(1):72–81.

[2] Salaffi F, Di Matteo A, Farah S, Di Carlo M. Inflammaging and Frailty in Immune-Mediated Rheumatic Diseases: How to Address and Score the Issue. Clinic Rev Allerg Immunol. 21 de maio de 2022;64(2):206–21.

Acknowledgements: The authors thank Edgard Torres dos Reis Neto, Elizabeth Jane James and Robin Hambly for the contributions to the translation/adaptation of SLICC-FI Pt-BR; Fabricia Fonseca Simil, Gilda Aparecida Ferreira, Marcela Paula Santos Penteado, Débora Cerqueira Calderaro and Anna Carolina Gomes Tavares for their contributions during lupus patient’s care; Rodrigo Alves Pinto for the statistical assistance; Maria Aparecida Camargos Bicalho, Alberto Frisoli Júnior and Evandro Mendes Klumb for the valuable critical analysis of this work; and Laboratório São Paulo for the partnership for anti-DNA tests.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.