Impact of obstructive sleep apnea on lung volumes and mechanical properties of the respiratory system in overweight and obese individuals

Table 5 Multiple stepwise regression analysis of the association of reactance measured at 5Hz with the severity of OSA

Model		Unstandardized Coefficients	Standardized Coefficients	t	P	95 % Confidence Interval for B		Correlation coefficients
Model		B	Beta	t	P	Lower Bound	Upper Bound	Zero-order	Partial	Part
1	Constant	2.623		0.916	0.361	−3.028	8.274
	X5	−173.294	−0.504	−7.784	<0.001	−217.288	−129.361	−0.504	−0.504	−0.504
2	Constant	−40.982		−4.404	<0.001	−59.344	−22.619
	X5	−144.800	−0.421	−6.659	<0.001	−187.714	−101.887	−0.504	−0.448	−0.406
	weight	0.584	0.310	4.896	<0.001	0.327	0.786	0.422	0.345	0.298
3	Constant	0.225		0.056	0.955	−7.775	8.225
	X5	−85.332	−0.482	−4.539	<0.001	−122.847	−47.819	−0.482	−0.482	−0.482
4	Constant	−25.415		−2.061	0.043	−50.035	0.796
	X5	−74.946	−0.424	−3.966	<0.001	−112.688	−37.223	−0.482	−0.436	−0.410
	BMI	0.912	0.234	2.191	0.032	0.081	1.744	0.340	0.259	0.227
5	Constant	−3.143		−1.046	0.299	−9.141	2.855
	X5	−84.601	−0.589	−6.002	<0.001	−112.726	−56.476	−0.589	−0.589	−0.589
6	Constant	−23.130		−2.059	0.015	−41.536	−4.726
	X5	−76.504	−0.532	−5.415	<0.001	−104.704	−48.305	−0.589	−0.552	−0.515
	BMI	0.711	0.225	2.258	0.025	0.090	1.333	0.358	0.269	0.217

Independent variables: Zrs5, Gz, sGz, Grs, sGrs, R5, X5, X10, X15; Dependent Variable: AHI or HI. Model 1, 2 derived from male subject data by performing stepwise regression analysis; model 3, 4 derived from female subject data; model 5, 6 derived from female subject data with HI as a dependent variable
Abbreviations: BMI body mass index, X5 respiratory system reactance at 5Hz, AHI apnea + hypopnea index, HI hypopnea index, Zrs5 respiratory system impedance at 5Hz (oscillatory frequency), R5 respiratory system resistance at 5 oscillatory frequencies, Grs respiratory conductance, reciprocal of R0 (total respiratory resistance, namely the resistance origin at the point of zero frequency), sGrs the specific Grs (the ratio of Grs to actual value of FRC), Gz reciprocal of Zrs5, sGz the specific Gz (the ratio of Gz to actual value of FRC)

ISSN: 1471-2466