Objectives: Interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are the leading causes of death in systemic sclerosis (SSc) patients. Although the six-minute walk test (6MWT) is used for evaluating ILD and PAH in clinical practice, no data are available on six-minute walk distance (6MWD) and oxygen desaturation in SSc patients without ILD and PAH.
Methods: Prospectively collected data of the 6MWTs at baseline and 6-month follow-up of 300 consecutive SSc patients, included in the Ghent University Hospital Systemic Sclerosis Unit between May 2006 and April 2015 were analysed.
Results: The mean 6MWD of 165 SSc patients without ILD and PAH who performed a 6MWT at baseline or at the 6-month visit was 484±93m. Patients in the diffuse cutaneous (DcSSc) subgroup (435±94m) walked less than in the limited (LSSc) subgroup (499±91m, p=0.04) and tended to walk less than in the limited cutaneous (LcSSc) subgroup (483±92m, p=0.15). In 115 SSc patients without ILD and PAH who walked at both moments, there was no significant difference between the 6MWDs (mean difference -7.60m 95%CI [-19.93m; 4.73m], p=0.23) and the oxygen desaturation was not statistically different in 102 of them (mean difference 0.41% 95%CI [-0.49%; 1.31%], p=0.37).
Conclusions: In SSc without ILD and PAH, the 6MWD and oxygen desaturation is clinically stable over a 6 months period. The DcSSc subgroup walks less than the LSSc and the LcSSc subgroup.