Effect of Weight Loss on the Apnea Hypopnea Index is Related to Waist Circumference in Chinese Adults with Overweight and Obesity

Figures & data

Table 1 Demographic Characteristics, Anthropometric Indicators and Body Composition in Overweight and Obese Patients According to AHI

Variable	Non-OSA (n = 20)	Mild OSA (n = 37)	Moderate OSA (n = 22)	Severe OSA (n = 58)	P
Demographic characteristics
Age, y	30(21,35)	30(26,34)	31(26,38)	34(30,39)	0.022
Male, n (%)	8(40.0)	14(37.8)	12(54.5)	50(86.2)^a,b,c	<0.001
Smoking, n (%)	2(10.0)	4(10.8)	4(18.2)	13(22.4)	0.454
Drinking, n (%)	1(5.0)	2(5.4)	2(9.1)	17(29.3)^a,b	0.005
Anthropometric measurements
Body weight, kg	80.9(70.4,93.4)	87.8(77.5,98.6)	96.7(85.4,107.0)^a	95.6(86.0,104.5)^a,b	0.001
BMI, kg/m^2	29.3(28.4,31.4)	32.4(29.6,35.3)^a	33.9(31.0,36.6)^a	33.1(30.9,35.9)^a	0.001
NC, cm	37.0(35.0,40.5)	38.5(36.8,41.5)	41.0(38.0,43.1)	42.0(40.8,44.0)^a,b	<0.001
WC, cm	94.5(89.3,101.8)	102.0(93.5,109.8)	107.3(99.7,115.1)^a	106.5(102.0,114.0)^a	<0.001
WHR	89.5(87.2,92.5)	92.7(89.7,97.9)	97.9(91.6,100.0)	99.1(96.7,103.5)^a,b	<0.001
Body composition
SMM, kg	27.6(23.7,38.3)	27.7(25.3,36.4)	31.8(28.7,38.9)	35.0(32.1,39.0)^a,b	0.001
FM, kg	27.7(25.0,35.7)	33.1(28.3,43.6)	36.7(31.2,46.1)^a	33.5(30.0,40.7)	0.023
FFM, kg	49.8(42.9,67.0)	49.5(45.2,63.6)	56.6(50.9,68.4)	62.1(56.7,68.8)^a,b	<0.001
PBF, % (SD)	36.6±6.4	39.7±6.1	40.1±6.6	36.3±5.4^b	0.009
BMFR	1.5(1.4,1.9)	1.5(1.2,1.7)	1.5(1.1,1.7)	1.8(1.5,1.9)^b	0.018
PSG data
AHI, events/h	2.45(1.43,3.68)	7.60(5.90,10.80)	21.25(17.58,22.63)^a,b	60.40(45.00,83.40)^a,b,c	<0.001

Notes: Data are expressed as mean ± SD, median with IQR, or percent frequency, as appropriate. ^aCompare to non-OSA, P<0.05; ^bCompare to mild OSA, P<0.05; ^cCompare to moderate OSA, P<0.05.

Abbreviations: OSA, obstructive sleep apnea; BMI, body mass index; NC, neck circumference; WC, waist circumference; WHR, waist–hip ratio; SMM, skeletal muscle mass; FM, fat mass; FFM, fat-free mass; PBF, percentage of body fat; BMFR, body muscle–fat ratio; AHI, apnoea-hypopnoea index.

Table 2 Multivariate Linear Regression Models for Predicting Log (AHI) in Overweight and Obese Patients

	β(SE)	β’	P value
Model 1
Age	1.417(0.378)	0.271	<0.001
Male	0.366(0.109)	0.314	0.001
NC	0.113(1.127)	0.010	0.920
WC	3.564(1.024)	0.294	0.001
R^2	0.334
Adjusted R^2	0.313
Model 2
Age	1.378(0.420)	0.260	0.001
Male	0.440(0.130)	0.367	0.001
BMI	2.374(0.991)	0.209	0.018
NC	−0.172(1.148)	−0.015	0.881
WHR	2.678(1.990)	0.142	0.181
R^2	0.373
Adjusted R^2	0.347
Model 3
Age	1.467(0.398)	0.285	<0.001
Male	0.556(0.162)	0.471	0.001
SMM	−0.544(0.417)	−0.130	0.195
FM	1.664(0.468)	0.317	0.001
FFM	0.334(1.034)	0.049	0.747
R^2	0.321
Adjusted R^2	0.295

Notes: R², R-square; β, unstandardized beta coefficients; β’, standardized beta coefficients.

Abbreviations: BMI, body mass index; NC, neck circumference; WC, waist circumstance; WHR, waist–hip ratio; SMM skeletal muscle mass; FM, fat mass; FFM, fat-free mass.

Table 3 Paired Comparisons of Anthropometric Indicators, Body Composition and AHI at Baseline and After a 12-Week Weight Loss Intervention

Variables	Baseline	12 Weeks	P value
Demographic characteristics
Body weight, kg	94.6±15.3	88.0±13.9	<0.001
BMI, kg/m^2	33.2±3.6	30.9±3.6	<0.001
Anthropometric measurements
Body weight, kg	94.6±15.3	88.0±13.9	<0.001
BMI, kg/m^2	33.2±3.6	30.9±3.6	<0.001
NC, cm	41.0(38.0,43.0)	39.5(37.6,42.0)	<0.001
WC, cm	106.5±10.9	99.2±10.7	<0.001
WHR	63.2±5.4	58.9±5.5	<0.001
Body composition
SMM, kg	33.3±6.0	32.5±5.6	<0.001
FM, kg	35.5±9.0	30.2±8.7	<0.001
FFM, kg	60.9(49.9,49.7)	59.2(49.7,66.7)	<0.001
PBF, %	37.0(33.1,42.5)	33.7(28.4,39.7)	<0.001
BMFR	1.6(1.3,1.9)	1.9(1.4,2.4)	<0.001
PSG
AHI, events/h	41.9(13.0,66.9)	20.7(8.7,51.2)	<0.001

Abbreviations: BMI, body mass index; NC, neck circumference; WC, waist circumference; WHR, waist–hip ratio; SMM skeletal muscle mass; FM, fat mass; FFM, fat-free mass; PBF, percentage of body fat; BMFR, body muscle–fat ratio; AHI, apnoea-hypopnoea index.

Figure 1 Association between percent change in WC, percent change in body weight and percent change in AHI. (A) Percent change in body weight had a positive association with that in WC; (B) percent change in WC had a positive association with that in AHI; (C) schematic diagram of WC as a mediator between percent change of body weight and AHI.

Notes: coefficient a, the effect of percent change in weight on percent change in WC; coefficient b, the effect of percent change in WC on percent change in AHI; coefficient c’, the direct effect of percent change in body weight on percent change in AHI. *p < 0.05, **p < 0.01.

Abbreviations: WC, waist circumference; AHI, apnoea-hypopnoea index.