Table 5. Correlation of lung function and respiratory muscle strength parameters with quality-of-life questionnaire scores in patients with Parkinson’s disease.

Variable	Quality of life
	PDQ-39, r (r2, %)	PDQ-39 mobility domain, r (r2, %)
FVC	−0.39 (15.2)*	−0.38 (14.4)*
FEV1	−0.36 (12.9)*	−0.36 (12.9)*
FEV1/FVC	0.20 (4.0)	0.17 (2.8)
PEF	−0.31 (9.6)*	−0.30 (9)*
FEF25-75%	−0.19 (3.6)	−0.22 (4.8)
MIP	0.24 (5.7)	0.27 (7.2)
MEP	−0.42 (17.64)*	−0.37 (13.6)*

PDQ-39: 39-item Parkinson’s Disease Questionnaire. *Pearson’s correlation; p < 0.05.