A frailty index developed by the Systemic Lupus International Collaborating Clinics (SLICC) could be a powerful and meaningful health measure to estimate vulnerability and mortality risk among patients with systemic lupus erythematosus (SLE), a study has found.
“The clinical course of SLE is highly variable and difficult to predict. Evaluation of SLE patients encompasses three core dimensions — disease activity, organ damage, and health-related quality of life (HRQoL), with each domain providing valuable prognostic information,” the researchers wrote.
In the past, SLICC, together with the American College of Rheumatology (ACR), developed the SLICC/ACR Damage Index (SDI), which estimates the incidence of adverse outcomes, including organ damage and mortality, in patients with SLE.
“However, the associations between disease activity, organ damage, and HRQoL in SLE are complex and the optimal approach for aggregating data across these domains is unclear,” the researchers said.
In an attempt to create a tool that would be able to incorporate all these aspects, SLICC created a frailty index (SLICC-FI), “which represents a state of increased vulnerability resulting in diminished ability to respond to physiologic stressors,” according to the study.
Researchers set out to test the suitability of the SLICC-FI to predict SLE patients’ mortality risk and provide additional prognostic information, compared with current health tools.
SLICC-FI was based on clinical data gathered during the participants’ first study visit (baseline) and incorporated a total of 48 health deficits linked to organ damage, disease activity, other comorbidities (coexisting conditions), and patients’ functional status. The SLICC-FI score was calculated by the sum of a patient’s health deficit scores divided by the total number of health deficits considered.
Besides SLICC-FI, organ damage was also evaluated at the start of the study by the SDI and health-related quality of life by the Short-Form 36 (SF-36).
The study involved a total of 1,683 SLE patients — 89% of whom were women — with an average age of 35.7 years and a mean disease duration of 18.8 months.
At the start of the study, the SLICC-FI score ranged from 0 to 0.51, with an average value of 0.17, and 27.5% of the patients were considered frail (SLICC-FI score higher than 0.21). These scores were in line with the researchers’ initial expectations and were poorly correlated with the SDI scores obtained at baseline.
After normalization for age, sex, ethnicity, medication use and baseline SDI scores, higher baseline SLICC-FI values were associated with a higher risk of death. For each 0.05 increment in this score, the risk of death increased by 59%.
A total of 1,507 SLE patients were present at the last follow-up visit, which took place an average of 7.2 years after the study’s start. Of these patients, 67.8% had a meaningful change (with differences greater than 0.03) in their SLICC-FI scores: 26.2% experienced a clinically meaningful increase in SLICC-FI scores, whereas 41.6% witnessed a significant decrease in SLICC-FI scores over the course of the study.
“In conclusion, evaluating frailty through deficit accumulation provides a holistic approach to prognostication among SLE patients, incorporating aspects of disease activity, organ damage, and HRQoL into a single measure,” the investigators wrote.
“We have demonstrated the SLICC-FI to be a meaningful health measure in SLE with the ability to vary over time and to predict mortality. Although the practical utility of frailty assessment in routine clinical care of SLE patients remains unexplored, the SLICC-FI holds promise as a clinical and research tool for the identification of vulnerable SLE patients. It may also be a valuable outcome measure for future intervention studies,” they concluded.