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

Table 4 Correlation coefficients between SGRQ scores, pulmonary function tests and arterial blood gas analysis

	Lung function measure	Correlation with SGRQ symptoms domain score	Correlation with SGRQ activity domain score	Correlation with SGRQ impact domain score	Correlation with SGRQ total score
Chang et al., 1999 [15]	DL_CO% predicted				−0.55^†
	FEV₁% predicted				−0.46^†
	FVC% predicted				−0.45^†
	TLC% predicted				−0.36^†
Nishiyama et al., 2005 [24]	PaO₂	−0.21	−0.48^†	−0.29	−0.37*
	SpO₂	−0.38*	−0.48^†	−0.22	−0.37*
	TLC	−0.48^†	−0.38*	−0.21	−0.36*
	TL_CO	−0.32*	−0.45^†	−0.27	−0.39*
	VC	−0.35*	−0.36*	−0.15	−0.30
Peng et al., 2008 [28]	DL_CO% predicted	−0.46^§	−0.46^§	−0.34^†	−0.44^‡
	FEV₁% predicted	NS	−0.53^§	−0.34^†	−0.42^§
	PaO₂	NS	−0.54^‡	NS	−0.32^†
	TLC% predicted	−0.50^§	−0.61^§	−0.52^§	−0.62^§
	VC% predicted	NS	−0.59^§	−0.35^†	−0.47^§
Tzanakis et al., 2005 [36]	FEV₁% predicted				−0.50^†
	PaO₂ (at rest)				−0.51^†
	PaO₂ (at exertion)				−0.60^†
	TLC% predicted				−0.55^†
Yorke et al., 2010¹[10]	FVC% predicted	−0.27^†	−0.31^§	−0.30^§	−0.34^§
Yorke et al., 2010¹[10]	TL_CO% predicted	−0.23^†	−0.34^§	−0.38^§	−0.38^§
Yorke et al., 2011 [39]	DL_CO%	−0.16	−0.37^†	−0.28*
Yorke et al., 2011 [39]	FVC%	−0.13	−0.16	−0.24*
Zimmermann et al., 2007 [40]	DL_CO% predicted	−0.41	−0.32	−0.39	−0.47*
	FEV₁% predicted	−0.08	−0.57*	−0.52*	−0.57*
	TLC% predicted	−0.37	−0.65*	−0.58*	−0.66*
	VC% predicted	−0.14	−0.54*	−0.61*	−0.56*

DL_CO = diffusion capacity of the lung for carbon monoxide; FEV₁ = forced expiratory volume in 1 second; FVC = forced vital capacity; PaO₂ = partial pressure of oxygen dissolved in arterial blood; TLC = total lung capacity, TL_CO = transfer factor of the lung for carbon monoxide; VC = vital capacity.
*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.

ISSN: 1477-7525