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Introduction: The 6-minute walk test (6MWT) is an accessible measure of outcome in parenchymal lung disease in SSc. We evaluated correlations of 6MWT with other established parameters in a well characterized group of patients with ILD secondary to SSc followed prospectively for 12 months.
Methods: 65 patients with SSc-ILD receiving placebo in a multi-center, randomized trial were evaluated at baseline and at 12 months with 6MWT, Borg dyspnea index, FVC, and DLco. Mean age was 54.5 ± 11 and mean disease duration 5.2 ± 6.6 years. 48 subjects (73.8%) were female. 29 (45%) were classified as limited and 36 (55%) as diffuse SSc.
Results: Mean 6MWT at baseline was 408 ± 87m and at 12 months 406.5 ± 84.2m; mean Borg dyspnea scale was 2.7 ± 2 at baseline and 2.5 ± 2 at 12 months; mean FVC at baseline was 2.6 ± 0.8L and at 12 months 2.6 ± 0.9L; mean DLco at baseline was 10.1 ± 4.7mmol/kPa.min and at 12 months 10.2 ± 4.6 mmol/kPa.min. Correlations between the 6MWT and Borg dyspnea index, FVC and DLco in the limited and diffuse SSc groups were:
* P≤ .01 (2-tailed), ** P≤.05 level (2-tailed)
Conclusions: These data confirm the stability of SSc-ILD over 12 months of observation and the high reproducibility of the 6MWT, Borg index, FVC and DLco. Data in the limited SSc sub-group show significant correlations between the 6MWT and DLco at baseline and follow-up as well as with the Borg dyspnea index at baseline. The diffuse SSc sub-group shows significant correlations between 6MWT and Borg index and FVC at follow-up but no correlation with DLco. Future interventional studies might address these potentially important differences between SSc subgroups.
Methods: 65 patients with SSc-ILD receiving placebo in a multi-center, randomized trial were evaluated at baseline and at 12 months with 6MWT, Borg dyspnea index, FVC, and DLco. Mean age was 54.5 ± 11 and mean disease duration 5.2 ± 6.6 years. 48 subjects (73.8%) were female. 29 (45%) were classified as limited and 36 (55%) as diffuse SSc.
Results: Mean 6MWT at baseline was 408 ± 87m and at 12 months 406.5 ± 84.2m; mean Borg dyspnea scale was 2.7 ± 2 at baseline and 2.5 ± 2 at 12 months; mean FVC at baseline was 2.6 ± 0.8L and at 12 months 2.6 ± 0.9L; mean DLco at baseline was 10.1 ± 4.7mmol/kPa.min and at 12 months 10.2 ± 4.6 mmol/kPa.min. Correlations between the 6MWT and Borg dyspnea index, FVC and DLco in the limited and diffuse SSc groups were:
| Limited SSc at 12 Baseline - - - Limited SSc at 12 months | ||||||||
| 6MWT | Borg Index | FVC | DLco | 6MWT | Borg Index | FVC | DLco | |
| 6MWT-baseline | 1 | -.441* | .361 | .511** | .652** | .044 | .319 | .511** |
| Borg-baseline | -.441* | 1 | -.273 | -.240 | -.240 | .605** | -.170 | -.194 |
| FVC-baseline | .361 | -.273 | 1 | .425* | .296 | -.362 | .957** | .383* |
| DLco-baseline | .511** | -.240 | .425* | 1 | .411** | -.252 | .428* | .929** |
| 6MWT-12 months | .652** | -.240 | .296 | .411* | 1 | -.328 | .346 | .451* |
| Borg-12 months | -.044 | .605* | -.362 | -.252 | -.328 | 1 | -.340 | -.227 |
| FVC-12 months | .319 | -.170 | .957** | .428* | .346 | -.340 | 1 | .414* |
| DLco-12 months | .511** | -.194 | .383* | .929** | .451* | -.227 | .414* | 1 |
| Diffuse SSc at 12 Baseline - - - Diffuse SSc at 12 months | ||||||||
| 6MWT | Borg Index | FVC | DLco | 6MWT | Borg Index | FVC | DLco | |
| 6MWT-baseline | 1 | -.307 | .200 | .063 | .680** | -.395* | .108 | .134 |
| Borg-baseline | -.307 | 1 | .073 | -.218 | -.260 | .597** | .121 | -.269 |
| FVC-baseline | .200 | .073 | 1 | -066 | .403* | -.043 | .980** | -.084 |
| DLco-baseline | .063 | -.218 | -.066 | 1 | .147 | -.223 | -.063 | .958** |
| 6MWT-12 months | .680** | -.250 | .403* | .147 | 1 | -.375* | .368* | .207 |
| Borg-12 months | -.395* | .597** | -.043 | -.223 | -.375* | 1 | .040 | -.310 |
| FVC-12 months | .108 | .121 | .980** | -.063 | .368* | .040 | 1 | -.077 |
| DLco-12 months | .134 | -.269 | -.084 | .958** | .207 | -.310 | -.077 | 1 |
* P≤ .01 (2-tailed), ** P≤.05 level (2-tailed)
Conclusions: These data confirm the stability of SSc-ILD over 12 months of observation and the high reproducibility of the 6MWT, Borg index, FVC and DLco. Data in the limited SSc sub-group show significant correlations between the 6MWT and DLco at baseline and follow-up as well as with the Borg dyspnea index at baseline. The diffuse SSc sub-group shows significant correlations between 6MWT and Borg index and FVC at follow-up but no correlation with DLco. Future interventional studies might address these potentially important differences between SSc subgroups.
E. Schiopu, Actelion, 2; Actelion, 8; A.J. Impens, Actelion, 2; K. Phillips, None; C.P. Denton, Actelion, 2; Actelion, 5; D.E. Furst, Actelion, 2; Actelion, 5; L. Guillevin, Actelion, 5; Actelion, 2; L.J. Rubin, Actelion, 2; Actelion, 5; A.U. Wells, Actelion, 2; Actelion, 5; M. Matucci-Cerinic, Actelion, 2; Actelion, 5; G. Riemekasten, Actelion, 2; Actelion, 5; P. Emery, Actelion, 2; Actelion, 5; H. Chadha-Boreham, Actelion, 3; P. Charef, Actelion, 3; S. Roux, Actelion, 3; C.M. Black, Actelion, 2; Actelion, 5; J.R. Seibold, Actelion, 2; Actelion, 5.