Correlation of diaphragm thickness with pulmonary function test in Parkinson’s disease

Table 3 Correlation between spirometry and clinical measures with ultrasound in late stage

	Diaphragm thickness during inspiration		Diaphragm thickness during expiration		Diaphragm fractional index
	r	P value	r	P value	r	P value
FVC	-0.225	0.229	-0.204	0.340	-0.067	0.754
FVC%	-0.006	0.978	0.091	0.672	-0.162	0.449
FEV1	-0.288	0.172	-0.212	0.320	-0.075	0.728
FEV1%	-0.040	0.853	0.144	0.501	-0.186	0.384
FEV1/FVC	0.129	0.549	-0.117	0.586	0.302	0.151
PEF	0.041	0.849	0.405	0.049	-0.476	0.019
PEF%	0.011	0.960	0.463	0.023	-0.617	0.001
MMEF	-0.259	0.233	-0.170	0.438	-0.113	0.608
MMEF%	-0.157	0.475	-0.113	0.607	-0.020	0.927
pSO2	0.282	0.182	0.189	0.377	0197	0.355
mMRC	0.045	0.864	0.286	0.265	-0.381	0.132
Age	0.065	0.762	-0.045	0.834	0.258	0.224
Heart rate	-0.413	0.045	-0.300	0.154	-0.167	0.436
Disease duration (months)	-0.053	0.805	-0.260	0.221	0.262	0.217

FVC: Forced vital capacity; FEV1: Forced expiratory volume in the first second; PEF: Peak expiratory flow; MMEF: Maximal-mid expiratory flow; mMRC: Modified medical research council; pSO₂: Peripheral oxygen saturation.