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. 2018 Jun 27;18:801. doi: 10.1186/s12889-018-5667-3

Table 4.

Results of the multilevel mediation models between Carstairs (exposure), physical environment variables (mediators), and biomarkers (outcomes)

FEV1% (England and Wales only)a SBPb BMIc CRPd
Estimate 95% CI Estimate 95% CI Estimate 95% CI Estimate 95% CI
Total effects (Carstairs predicting biomarker, no mediators, c path)
 Carstairs (c) −0.617 − 0.706, − 0.528 0.191 0.105, 0.277 0.154 0.124, 0.183 0.060 0.048, 0.073
Direct effects (Carstairs predicting biomarker net of mediators; c’, a1-a7, and b1-b7 paths)
Within
 Age – 0.468 0.455, 0.482 0.044 0.039, 0.049 0.015 0.013, 0.018
 Gender – −6.859 −7.315, −6.403 −0.098 −0.238, 0.043 0.292 0.221, 0.362
 Log income 3.990 2.716, 5.264 −1.024 −2.090, 0.041 0.124 −0.230, 0.478 −0.298 − 0.454, − 0.142
Between
 Carstairs (c’) −0.548 − 0.653, − 0.442 0.212 0.112, 0.312 0.182 0.148, 0.215 0.056 0.041, 0.071
 Log income (on Carstairs) −9.143 −10.420, −7.865 − 9.772 − 11.744, − 7.801 −9.761 −11.727, − 7.795 −9.777 −11.752, − 7.801
Carstairs predicting mediators:
 SO2 (a1) 0.181 0.161, 0.201 0.147 0.129, 0.165 0.147 0.129, 0.165 0.147 0.129, 0.165
 PM10 (a2) 0.186 0.169, 0.203 0.127 0.108, 0.146 0.127 0.108, 0.146 0.127 0.108, 0.146
 NO2 (a3) 0.940 0.867, 1.012 0.791 0.717, 0.864 0.791 0.717, 0.864 0.791 0.717, 0.864
 CO (a4) 0.010 0.010, 0.011 0.009 0.009, 0.010 0.009 0.009, 0.010 0.009 0.009, 0.010
 Green space (a5) −4.184 −4.381, −3.986 −3.911 −4.097, − 3.724 −3.911 −4.097, − 3.724 −3.911 −4.097, − 3.724
 Industrial facilities (a6) 0.004 0.002, 0.006 0.004 0.002, 0.005 0.004 0.002, 0.005 0.004 0.002, 0.005
Mediators predicting biomarker:
 SO2 (b1) 0.066 −0.075, 0.208 0.424 0.285, 0.562 0.098 0.056, 0.140 0.023 0.003, 0.043
 PM10 (b2) −0.134 −0.491, 0.223 − 0.661 −0.961, − 0.361 −0.093 − 0.195, 0.009 0.051 0.005, 0.097
 NO2 (b3) −0.012 −0.121, 0.097 0.002 −0.098, 0.101 0.016 −0.018, 0.050 − 0.023 −0.039, − 0.008
 CO (b4) 0.376 −11.969, 12.721 2.783 −7.933, 13.499 −5.089 −8.907, −1.270 1.196 −0.510, 2.901
 Green space (b5) 0.011 −0.005, 0.027 0.007 −0.007, 0.021 0.000 −0.005, 0.004 0.000 −0.002, 0.002
 Industrial facilities (b6) −0.846 −2.199, 0.506 0.707 −0.613, 2.028 0.554 0.117, 0.991 0.173 −0.026, 0.371
Indirect effects (a*b)
Between
 Total Indirect −0.069 −0.132, − 0.007 −0.021 − 0.077, 0.034 −0.028 − 0.047, − 0.009 0.004 −0.004, 0.012
 SO2 (a1*b1) 0.012 −0.014, 0.038 0.062 0.041, 0.084 0.014 0.008, 0.021 0.003 0.000, 0.006
 PM10 (a2*b2) −0.025 −0.091, 0.042 − 0.084 −0.124, − 0.044 −0.012 − 0.025, 0.001 0.006 0.001, 0.012
 NO2 (a3*b3) −0.011 −0.114, 0.091 0.001 −0.077, 0.080 0.013 −0.014, 0.039 − 0.018 −0.031, − 0.006
 CO (a4*b4) 0.004 −0.123, 0.131 0.025 −0.072, 0.122 − 0.046 −0.081, − 0.011 0.011 −0.005, 0.026
 Green space (a5*b5) −0.045 −0.112, 0.022 − 0.029 −0.084, 0.026 0.001 −0.017, 0.019 0.001 −0.007, 0.009
 Industrial facilities (a6*b6) −0.004 −0.010, 0.002 0.002 −0.002, 0.007 0.002 0.000, 0.004 0.001 0.000, 0.001
Model fit statistics X2 = 178.847, df = 12, p < .0001; RMSEA = 0.027; CFI = 0.991; TLI = 0.972, SRMR W = 0.003; SRMR B = 0.049 X2 = 258.072, df = 14, p < .0001; RMSEA = 0.029; CFI = 0.990; TLI = 0.971, SRMR W = 0.018; SRMR B = 0.046 X2 = 264.759, df = 14, p < .0001; RMSEA = 0.029; CFI = 0.988; TLI = 0.965, SRMR W = 0.018; SRMR B = 0.050 X2 = 263.910, df = 14, p < .0001; RMSEA = 0.029; CFI = 0.988; TLI = 0.964, SRMR W = 0.017; SRMR B = 0.047

FEV1% percent predicted forced expiratory volume in 1 s, SBP systolic blood pressure, BMI body mass index, CRP C-reactive protein, Bolded data are significant