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Abstract
Background Frailty is associated with adverse health outcomes in systemic lupus erythematosus (SLE). We aimed to assess the agreement between two frailty measures, the SLICC Frailty Index (SLICC-FI) and the FRAIL scale, for identifying frailty among SLE patients. We also evaluated differences in characteristics between frail and non-frail SLE patients according to each frailty definition.
Methods This was a cross-sectional study of consecutive adult SLE patients assessed in the Lupus Clinic at a single academic medical centre from December 2020-November 2021. At a single visit, participants were assessed for disease activity, organ damage, comorbidities, medications, and health-related quality of life (HRQoL). A SLICC-FI score was calculated for each patient. The 5-item FRAIL scale was administered at the same visit. Agreement between the SLICC-FI and the FRAIL scale was evaluated. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal threshold SLICC-FI value based on agreement with the FRAIL scale.
Results The 181 SLE patients were mostly female (90.1%) with mean (SD) age 54.6 (14.3) years. Mean (SD) baseline SLICC-FI score was 0.17 (0.08), with 57 patients (31.5%) classified as frail (SLICC-FI >0.21). Based on the FRAIL scale, 31 patients (17.1%) were classified as frail (≥3/5 items). There was moderate correlation between the FRAIL scale and the SLICC-FI (r=0.639; p<0.0001). Agreement occurred in 84.5% of cases (κ=0.591; p<0.0001). The ROC curve analysis yielded an AUC of 0.936 (figure 1). The existing SLICC-FI cut-off value of >0.21 was the optimal threshold (sensitivity 96.8%, specificity 82%). For both frailty definitions, there were significant differences between frail and non-frail SLE patients in terms of age, education, employment status, organ damage, HRQoL, CRP levels, and ESR values (table 1).
Conclusions There is moderate agreement between the SLICC-FI and the FRAIL scale for identifying frailty in SLE patients. Each frailty metric may have distinct advantages in different settings.
Receiver operating characteristic (ROC) curve for SLICC frailty index (SLICC-FI) values, based on agreement with frailty status as determined by the FRAIL scale
Clinical and laboratory characteristics of SLE patients based on frailty status (n=181)
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