Table 2.

Linear mixed regression models by survey

Variable	SBP	DBP	BMI
NHANES
Intercept	112.891 [112.120; 113.662]	70.438 [69.812; 71.065]	24.136 [23.853; 24.419]
Degree (ref. other qualification)	− 2.903 [− 3.596; − 2.210]	− 0.609 [− 1.042; − 0.175]	− 1.124 [− 1.386; − 0.861]
No qualification	1.870 [1.342; 2.397]	0.213 [− 0.117; 0.544]	0.682 [0.482; 0.882]
Year	− 0.058 [− 0.094; − 0.022]	− 0.387 [− 0.412; − 0.363]	0.197 [0.184; 0.211]
Degree x Year	0.030 [− 0.007; 0.066]	0.054 [0.032; 0.077]	− 0.028 [− 0.042; − 0.015]
No qualification x Year	− 0.029 [− 0.059; 0.001]	− 0.031 [− 0.050; − 0.013]	− 0.041 [− 0.052; − 0.030]
n	144703	144703	141791
m	148	148	148
HSE
Intercept	127.311 [126.765; 127.857]	66.317 [65.970; 66.664]	23.412 [23.305; 23.520]
Degree (ref. other qualification)	− 1.010 [− 1.432; − 0.589]	1.108 [0.824; 1.393]	− 0.453 [− 0.576; − 0.329]
No qualification	4.181 [3.876; 4.485]	2.984 [2.779; 3.190]	0.500 [0.411; 0.590]
Year	− 0.607 [− 0.621; − 0.592]	− 0.066 [− 0.076; − 0.057]	0.086 [0.082; 0.090]
Degree x Year	0.004 [− 0.022; 0.030]	− 0.059 [− 0.077; − 0.042]	− 0.022 [− 0.029; − 0.014]
No qualification x Year	− 0.223 [− 0.246; − 0.201]	− 0.241 [− 0.257; − 0.226]	0.008 [0.002; 0.015]
n	189552	189552	178475
m	32	32	32
SHS
Intercept	121.097 [119.719; 122.476]	66.370 [65.458; 67.283]	23.695 [23.314; 24.076]
Degree (ref. other qualification)	− 0.748 [− 2.159; 0.663]	0.355 [− 0.574; 1.284]	0.160 [− 0.280; 0.599]
No qualification	3.118 [1.864; 4.371]	0.389 [− 0.437; 1.214]	0.762 [0.369; 1.154]
Year	− 0.246 [− 0.309; − 0.183]	0.045 [0.003; 0.086]	0.099 [0.082; 0.116]
Degree x Year	0.002 [− 0.072; 0.077]	− 0.027 [− 0.076; 0.022]	− 0.047 [− 0.070; − 0.024]
No qualification x Year	− 0.142 [− 0.218; − 0.066]	− 0.049 [− 0.099; 0.001]	− 0.012 [− 0.035; 0.012]
n	22511	22511	20833
m	21	21	21

Coefficients $\beta$ and 99% confidence intervals. m and n: number of random-effect strata levels and sample size, respectively. SBP, DBP systolic and diastolic blood pressure. BMI body-mass-index