Table 4 Correlation coefficients between estimates of sodium or sodium-to-potassium ratio by empirical weight or by FFQ (food composition procedure) and those measured by 24-h urinary excretion: applied to the responses to FFQ2 for the remaining half of participants.

		Measured value by urinary excretion	Prediction expression intake behavior items only			Prediction expression with characteristics			Estimated by food composition approach
		Measured value by urinary excretion	Estimated value^¶	CC^†		Estimated value^¶	CC^†		Estimated value	CC^†
		Mean ± SD	Mean ± SD	Crude	Adjusted^a	Mean ± SD	Crude	Adjusted^a	Mean ± SD	Crude	Adjusted^ab
Sodium excretion (mg/day)	All (n = 118)	4305 ± 1212	4194 ± 504	0.32**	0.36	4147 ± 544	0.45**	0.52	4479 ± 2319	0.16	0.29
	M (n = 48)	4734 ± 1148	4269 ± 528	0.35*	0.41	4414 ± 435	0.35**	0.42	4167 ± 2231	0.32**	0.46
	F (n = 70)	4011 ± 1174	4142 ± 485	0.27*	0.30	3964 ± 539	0.38**	0.43	4693 ± 2370	0.17	0.29
Sodium-to-potassium ratio (mmol ratio)	All (n = 118)	3.47 ± 1.11	3.40 ± 0.71	0.48**	0.53	3.39 ± 0.73	0.50**	0.58	2.97 ± 0.81	0.33**	0.36
	M (n = 48)	3.81 ± 1.17	3.71 ± 0.61	0.45**	0.50	3.87 ± 0.55	0.45**	0.49	3.06 ± 0.89	0.35**	0.38
	F (n = 70)	3.23 ± 1.02	3.19 ± 0.70	0.42**	0.46	3.07 ± 0.66	0.45**	0.50	2.92 ± 0.75	0.29*	0.33

M Male, F Female.
^†Spearman's Correlation coefficient between measured and predicted value.
**P value < 0.01.
*P value < 0.05.
^¶For the remaining half of FFQ2 respondents, using the equation from the FFQ2-developing group. The individual responses for each item were transformed accordingly into ordinal variables (or directly into continuous or nominal variables, as shown in the Table 3 footnote), then multiplied by the regression coefficients for each item, and the sum of these and the value of the intercept is the predicted value.
^aAdjusted CC = observed CC × SQRT (1 + λx/n), where λx is the ratio of within- to between-individual variance for number of urine collection.
^bCalculating energy-adjusted values (other than Na/K ratio) before deattenuated.

Search