Self-reporting and measurement of body mass index in adolescents: refusals and validity, and the possible role of socioeconomic and health-related factors

Table 5 Relationships of weight self-perception with reporting refusal, measurement refusal, BMIsr under-reporting or BMIsr over-reporting (vs. correct reporting) and roles of covariates (N = 1559): odds ratio (OR) and 95% confidence interval (CI)

	Reporting refusal		Measurement refusal		BMIsr under-reporting (with change in BMI category; vs. correct reporting)		BMIsr over-reporting (with change in BMI category; vs. correct reporting)
	OR	%	OR	%	OR	%	OR	%
	95% CI		95% CI		95% CI		95% CI
Weight perception
Feeling too fat (vs. feeling the right weight)
Crude OR	2.39†		1.46		1.80‡		2.61‡
Crude OR	1.25-4.56		0.97-2.18		1.25-2.58		1.56-4.36
Model 1	2.38*	100	1.46	‒	0.56†	100	5.07‡	100
Model 1	1.18-4.79		0.97-2.18		0.37-0.86		2.91-8.83	100
Model 2	1.77	44	1.01	‒	0.55†	2	8.40‡	-82
Model 2	0.82-3.81		0.64-1.58		0.35-0.89		4.41-16.0	-82
Feeling too thin (vs. feeling the right weight)
Crude OR	3.43‡		1.12		1.23		1.76
Crude OR	1.60-7.39		0.61-2.06		0.71-2.12		0.84-3.72
Model 1	3.61†	100	1.12	‒	6.32‡	100	1.17	‒
Model 1	1.63-8.01	100	0.61-2.06	‒	2.91-13.7	100	0.52-2.64	‒
Model 2	3.35†	10	1.05	‒	7.23‡	-17	1.00	‒
	1.45-7.74		0.55-2.00		3.26-16.0		0.41-2.46

*p < 0.05, †p < 0.01, ‡p < 0.001.
BMI: Body mass index; BMIsr: self-reported BMI.
Model 1: adjusted for measured BMI (except for measurement refusal).
Model 2: with further adjustment for socioeconomic factors and health-related and behavioural factors (Table 4).
% = Reduction (positive%) or increase (negative%) in OR computed with the following formula: (OR _{model 1}–HR _model2)/(OR _{model 1}–1).

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