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Table 1 Proportional hazards models predicting 45-year all-cause mortality (1447 deaths among 1591 men) by three methods

From: Artificial neural networks versus proportional hazards Cox models to predict 45-year all-cause mortality in the Italian Rural Areas of the Seven Countries Study

  Forced Cox model Forward stepwise Cox model Backward stepwise Cox model
(N = 1591) (N = 1591) (N = 1591)
β t HR(±95%CI) β t HR(±95%CI) β t HR(±95%CI)
Age (years) 0.1024 16.81 1.68(1.58-1.79) 0.1017 16.78 1.67(1.58-1.78) 0.1029 17.01 1.69(1.59-1.79)
Father status (codes 0–1) 0.1422 2.19 1.15(1.01-1.31) 0.1421 2.19 1.15(1.01-1.31) 0.1436 2.21 1.15(1.02-1.31)
Mother status (codes 0–1) 0.2063 3.11 1.23(1.08-1.40) 0.2121 3.22 1.24(1.09-1.41) 0.2072 3.16 1.23(1.08-1.40)
Family history of CVD (codes 0–1) 0.0326 0.60 1.03(0.93-1.15) = = = = = =
Corneal arcus (codes 0–1) 0.2092 2.70 1.23(1.06-1.43) 0.1988 2.57 1.22(1.05-1.42) 0.2037 2.63 1.23(1.05-1.43)
Physical activity (codes 1-2-3) −0.0830 −1.92 0.92(0.85-1.00) = = = −0.1042 −2.51 0.90(0.83-0.98)
Cigarettes smoked per day (N) 0.0174 6.26 1.18(1.12-1.24) 0.0177 6.37 1.18(1.12-1.25) 0.0177 6.36 1.18(1.12-1.25)
Body mass index (Kg/m2) −0.1840 −2.77 0.51(0.31-0.82) −0.1711 −2.62 0.53(0.33-0.85) −0.2097 −3.30 0.46(0.29-0.73)
Body mass index2 [(Kg/m2)2] 0.0033 2.70 1.90(1.19-3.04) 0.0031 2.62 1.85(1.17-2.93) 0.0036 3.03 2.02(1.28-3.18)
Arm circumference (cm) −0.0026 −1.64 0.94(0.88-1.01) −0.0034 −2.21 0.92(0.86-0.99) = = =
Mean blood pressure (mmHg) 0.0180 7.76 1.28(1.20-1.36) 0.0186 8.24 1.29(1.21-1.36) 0.0189 8.43 1.29(1.22-1.37)
Heart rate (beats/min) 0.0018 0.78 1.02(0.97-1.09) = = = = = =
Serum cholesterol (mmol/l) 0.0722 2.81 1.08(1.02-1.14) 0.0758 2.97 1.08(1.03-1.14) 0.0751 2.94 1.08(1.03-1.14)
Forced expiratory volume (l/m2) −0.4691 −3.93 0.89(0.84-0.94) −0.4815 −4.05 0.89(0.84-0.94) −0.4742 −3.99 0.89(0.84-0.94)
ECGm abnormalities (codes 0–1) 0.0518 0.47 1.05(0.85-1.31) = = = = = =
Prevalence CVD (codes 0–1) 0.3658 2.85 1.44(1.12-1.85) 0.3520 2.75 1.42(1.11-1.83) 0.3905 3.05 1.48(1.15-1.90)
Prevalence K (codes 0–1) 2.1479 4.72 8.57(3.51-20.89) 2.2056 4.87 9.08(3.73-22.07) 2.1644 4.76 8.71(3.58-21.22)
Prevalence DIAB (codes 0–1) 0.2545 2.06 1.29(1.01-1.64) 0.2502 2.02 1.28(1.01-1.64) 0.2674 2.16 1.31(1.03-1.66)
ROC ± standard error (±95%CI)   0.829 ± 0.0137 (0.810-0.847)    0.830 ± 0.0136 (0.811-0.849)    0.830 ± 0.0137 (0.810-0.848)  
  1. β = coefficient; t = t value of coefficient (when t > |1.96| p<0.05); HR = hazard ratio; CI = confidence intervals. The differences for hazards ratio are expressed as 0–1 for dichotomic variables, as 1 unit for physical activity, and as standard deviations for continuous variables.
  2. CVD = cardiovascular disease; DIAB = diabetes; ECGm = minor ECG; K = cancer.
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