Severity and features of frailty in systemic sclerosis-associated interstitial lung disease

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is characterized by multiple symptoms and comorbidities. The cumulative impact of these deficits can be summarized using the concept of frailty; however, frailty has not been characterized in patients with SSc-ILD.

Patients with SSc-ILD and non-CTD fibrotic ILD were recruited from specialized clinics. Frailty was assessed using a 42-item patient-reported Frailty Index, calculated as the proportion of reported deficits divided by the total number of surveyed items. Frailty was defined as a Frailty Index >0.21. Unadjusted and multivariate analyses were used to identify correlates of frailty.

The study cohort included 86 patients with SSc-ILD and 167 patients with non-CTD fibrotic ILD. The mean age in SSc-ILD was 60.5 years, 80% were women, and on average patients had mild to moderate restrictive lung function impairment (mean FVC 78%-predicted, DLCO 51%-predicted). The mean Frailty Index was 0.23 ± 0.15, with 55% of the SSc-ILD population meeting criteria for frailty. Dyspnea had the strongest association with the Frailty Index (r = 0.62, p < 0.001) and was the only variable independently associated with frailty on multivariate analysis. Frailty severity was similar in SSc-ILD and non-CTD fibrotic ILD, including with adjustment for differences in baseline cohort characteristics.

Frailty is highly prevalent in patients with SSc-ILD, indicating that chronological age significantly underestimates biological age in this population. Dyspnea is the variable with the strongest association with frailty in SSc-ILD; however, future studies are needed to identify additional modifiable determinants of frailty and the ability of frailty to predict outcomes in SSc-ILD.