Reproducibility of pulmonary function tests in patients with systemic sclerosis.

Area of Science:

• Pulmonary Medicine
• Rheumatology
• Autoimmune Diseases

Background:

• Systemic sclerosis (SSc) is a rare autoimmune disease where interstitial lung disease (ILD) significantly increases morbidity and mortality.
• Clinical management of SSc-ILD relies heavily on pulmonary function testing (PFTs) and tracking changes over time.
• Limited data exists on the reproducibility of PFTs in SSc patients, crucial for reliable disease monitoring.

Purpose of the Study:

• To assess the test-retest reliability and 30-day reproducibility of PFTs in SSc patients.
• To determine potential physiologic variations in PFT parameters over time.
• To compare PFT reproducibility between SSc patients with and without ILD.

Main Methods:

• Prospective observational study involving 25 SSc patients (14 with ILD, 11 without).
• PFT parameters (FVC, FEV1/FVC ratio, DLCO, KCO) measured at four timepoints: T0, 3 hours (H3), 15 days (D15), and 30 days (D30).
• Statistical analysis included mixed linear models and Bland-Altman tests to evaluate reproducibility and time/group effects.

Main Results:

• No significant influence of time or group (ILD vs. non-ILD) on FVC, FEV1/FVC ratio, or DLCO measurements.
• PFT parameters demonstrated reproducibility over the 30-day study period.
• Bland-Altman analysis confirmed reproducibility for FVC and DLCO in both groups.

Conclusions:

• Pulmonary function tests are reproducible over time in clinically stable SSc patients.
• No significant differences in PFT reproducibility were observed between SSc patients with and without ILD.
• These findings support the continued use of PFTs in the clinical management of SSc patients.