Baseline disease activity index and forced vital capacity predict clinically meaningful complications and mortality in systemic sclerosis.

OBJECTIVE

The objective of this study was to evaluate whether the modified disease activity index (mDAI) predicts subsequent disease progression and organ damage in SSc.

METHODS

We analysed 227 patients diagnosed with SSc who were enrolled in a prospective SSc registry. Baseline disease activity was assessed using the modified EUSTAR disease activity index (mDAI), with active disease being defined as an mDAI of ≥2.5. The primary outcome was a composite of disease-related clinically meaningful complications-based on revised CRISS step 1 events (interstitial lung disease progression, precapillary pulmonary hypertension, scleroderma renal crisis, heart failure, severe digital ischaemia, or severe gastrointestinal dysfunction)-or all-cause mortality. Associations were examined using Cox proportional hazards models.

RESULTS

At baseline, 42 (18.5%) had active disease. During a median follow-up period of 38 months, 45 (19.7%) patients had experienced the primary outcome. Active disease was associated with a higher risk of events (log-rank P < 0.001). In multivariable analysis, baseline active disease [hazard ratio (HR) 2.21, 95% CI 1.06-4.59] and a lower forced vital capacity (HR 0.98 per %, 95% CI 0.96-0.99) independently predicted adverse outcomes. Results were consistent across sensitivity analyses using alternative end point definitions.

CONCLUSION

Baseline mDAI and forced vital capacity independently predict disease-related clinically meaningful complications and mortality in SSc. The mDAI provides a simple, feasible tool for risk stratification beyond progression of interstitial lung disease.