The psychometric properties of the St George’s Respiratory Questionnaire (SGRQ) in patients with idiopathic pulmonary fibrosis: a literature review

Table 3 Correlation coefficients between SGRQ scores and the 6MWD as a measure of exercise capacity

	Measure	Correlation with SGRQ symptoms domain score	Correlation with SGRQ activity domain score	Correlation with SGRQ impact domain score	Correlation with SGRQ total score
Cross-sectional studies
Chang et al., 1999 [15]	6MWD				−0.66^†
du Bois et al., 2011 [16]	6MWD				−0.26^‡
Peng et al., 2008 [28]	6MWD	−0.32^†	−0.43^‡	−0.41^‡	−0.45^‡
Yorke et al., 2010¹[10]	6MWD	−0.14	−0.32^§	−0.24^†	−0.28^†
Yorke et al., 2011 [39]	6MWD	−0.32^†	−0.54^†	−0.47^†
Zimmermann et al., 2007 [40]	6MWD	−0.41	−0.72*	−0.63*	−0.72*
Longitudinal studies
du Bois et al., 2011 [16]	Δ 6MWD				−0.231^‡
Nishiyama et al., 2008 [25]	Δ 6MWD				−0.43*
Peng et al., 2008 [28]	Δ 6MWD	NS	−0.43	−0.46	−0.41^†

6MWD = Distance covered in 6-minute walk test; Δ = change.
*p < 0.05; ^†p < 0.01; ^‡p < 0.001; ^§p < 0.0001; NS = non-significant. ¹Data reported refer to the original version of the SGRQ, not the SGRQ-I.

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