Evaluating the Properties of a Frailty Index and Its Association With Mortality Risk Among Patients With Systemic Lupus Erythematosus


Legge A., Kirkland S., Rockwood K., Andreou P., BAE S., Gordon C., ...More

ARTHRITIS & RHEUMATOLOGY, vol.71, no.8, pp.1297-1307, 2019 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 71 Issue: 8
  • Publication Date: 2019
  • Doi Number: 10.1002/art.40859
  • Journal Name: ARTHRITIS & RHEUMATOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1297-1307
  • Istanbul University Affiliated: Yes

Abstract

Objective To evaluate the properties of a frailty index (FI), constructed using data from the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort, as a novel health measure in systemic lupus erythematosus (SLE). Methods For this secondary analysis, the baseline visit was defined as the first study visit at which both organ damage (SLICC/American College of Rheumatology Damage Index [SDI]) and health-related quality of life (Short-Form 36 [SF-36] scores) were assessed. The SLICC-FI was constructed using baseline data. The SLICC-FI comprises 48 health deficits, including items related to organ damage, disease activity, comorbidities, and functional status. Content, construct, and criterion validity of the SLICC-FI were assessed. Multivariable Cox regression was used to estimate the association between baseline SLICC-FI values and mortality risk, adjusting for demographic and clinical factors. Results In the baseline data set of 1,683 patients with SLE, 89% were female, the mean +/- SD age was 35.7 +/- 13.4 years, and the mean +/- SD disease duration was 18.8 +/- 15.7 months. At baseline, the mean +/- SD SLICC-FI score was 0.17 +/- 0.08 (range 0-0.51). Baseline SLICC-FI values exhibited the expected measurement properties and were weakly correlated with baseline SDI scores (r = 0.26, P < 0.0001). Higher baseline SLICC-FI values (per 0.05 increment) were associated with increased mortality risk (hazard ratio 1.59, 95% confidence interval 1.35-1.87), after adjusting for age, sex, steroid use, ethnicity/region, and baseline SDI scores. Conclusion The SLICC-FI demonstrates internal validity as a health measure in SLE and might be used to predict future mortality risk. The SLICC-FI is potentially valuable for quantifying vulnerability among patients with SLE, and adds to existing prognostic scores.