PT - JOURNAL ARTICLE AU - Margaret C. Garin AU - Kristin B. Highland AU - Richard M. Silver AU - Charlie Strange TI - Limitations to the 6-Minute Walk Test in Interstitial Lung Disease and Pulmonary Hypertension in Scleroderma AID - 10.3899/jrheum.080447 DP - 2009 Jan 15 TA - The Journal of Rheumatology PG - jrheum.080447 4099 - http://www.jrheum.org/content/early/2009/01/22/jrheum.080447.short 4100 - http://www.jrheum.org/content/early/2009/01/22/jrheum.080447.full AB - Objective To determine factors that influence 6-minute walk distance (6MWD) in patients with scleroderma (systemic sclerosis, SSc)-interstitial lung disease (ILD), SSc-pulmonary hypertension (PH), and idiopathic pulmonary fibrosis (IPF). Methods We retrospectively evaluated all patients with SSc or IPF who performed a 6-minute walk test (6MWT) at a university hospital between 1999 and 2003. Chi-square, ANOVA, simple linear regression, and backwards elimination multivariable regressions were performed. Results Forty-eight consecutive IPF patients with 6MWT were compared to 33 patients with SSc-ILD, 13 with SSc-PH, 19 with both SSc-ILD and SSc-PH (SSc-Both), and 15 with SSc without ILD or PH (SSc-Neither). Mean 6MWD did not differ between groups. Limitations to 6MWT trended toward dyspnea in IPF and lower extremity pain in SSc. SSc-Both had dyspnea limitation more than other SSc subgroups (p = 0.017). Percentage predicted forced vital capacity (FVC%) and percentage predicted carbon monoxide diffusing capacity (DLCO%) were more strongly predictive of 6MWD in IPF than in SSc; however, exclusion of SSc subjects with pain limitation improved the predictive value. Significant correlates of 6MWD in multivariable analysis differed between subgroups. Conclusion Pain limitations confound the utility of the 6MWT, particularly in SSc. Pain may cause failure to reach a dyspnea limitation during 6MWT, especially in SSc patients without both ILD and PH. Correlates of 6MWD differ between SSc subgroups and IPF; therefore, the 6MWT distance is not always reflective of the same physiological process. 6MWT interpretation should include consideration of vascular, pulmonary, and musculoskeletal exercise limitations.