Validity of self-measured waist circumference in adults at risk of type 2 diabetes and cardiovascular disease

Table 1 Mean (SD) self-measured waist circumference and objectively measured waist circumference and their mean differences (95% CI) stratified by anthropometric, demographic and behavioural characteristics

Categories	n	SMWC		OMWC		SMWC- OMWC mean (95%CI)^a			P-value^b
Categories	n	Mean	SD	Mean	SD	Mean	Low	High	P-value^b
Overall	617	102.6	10.1	96.6	9.7	6.0	6.4	5.6	<0.01^b
Age^c
Younger	309	103.9	10.6	97.4	9.8	6.4	6.9	5.9	0.02^b
Older	308	101.3	9.4	95.8	9.6	5.5	6.1	5.0	0.02^b
Education
Primary	201	103.5	11.2	96.9	11.1	6.6	7.3	5.9	0.03^b
Secondary	285	102.7	9.8	96.8	9.3	5.9	6.5	5.4
College	128	100.8	8.7	95.6	8.2	5.2	6.0	4.4
Body mass index^d
Normal	84	93.7	6.1	87.3	6.0	6.4	7.5	5.3	0.56
Overweight	333	100.3	7.6	94.5	7.3	5.8	6.3	5.3
Obese	200	110.1	10.3	104.0	9.4	6.1	6.8	5.4
Dietary behaviour^e
Yes	47	99.3	9.1	94.1	9.1	5.2	6.6	3.8	0.23
No	531	102.7	10.1	96.7	9.7	6.1	6.5	5.7	0.23
Smoking behaviour^f
Yes	126	104.3	11.5	97.9	10.7	6.4	7.1	5.6	0.33
No	487	102.1	9.7	96.2	9.4	5.9	6.3	5.5	0.33
Physical activity^g
Yes	383	101.8	9.8	96.1	9.4	5.8	6.3	5.3	0.26
No	230	103.8	10.6	97.4	10.3	6.4	7.0	5.8	0.26
Sedentary behaviour^h
Yes	542	102.8	10.1	96.8	9.8	6.0	6.4	5.6	0.74
No	69	100.4	10.0	94.5	9.0	5.8	6.9	4.7	0.74

Abbreviations: OMWC, objectively measured waist circumference; SMWC, self-measured waist circumference.
^aDifference calculated as self-measured minus objectively WC values, note that negative and positive values indicates under and over -estimation, respectively.
^bSignificant differences (P < 0.05).
^cAge groups: younger ≤44.07 years and older >44.07 years.
^dBody mass index: normal <25.0 kg/m², overweight≥25.0 to <29.9 kg/m², obese ≥30.0 kg/m².
^eDiet: Yes: meeting recommendations of at least two pieces of fruit and 200 g of vegetables intake per day; No: not meeting these recommendations.
^fSmoking behaviour: Yes: current smoker: No: not current smoker.
^gPhysical activity: Yes: meeting the national recommendations of being physically active (≥30 minutes moderate-intensity physical activity), No: not meeting these recommendations.
^hSedentary Behaviour: Yes: sedentary (≥2 hours per day activities with an energy expenditure of under 2 METs); No: not meeting these recommendations.

ISSN: 1741-7015