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Table 4 Vector Autoregressive Model Evaluating Prediction of Pertussis Test Positivity by Lagged Pertussis Positivity and Test Submissions

From: Pertussis resurgence in Toronto, Canada: a population-based study including test-incidence feedback modeling

Independent Variable and Lag Entire Study Period (1993-2007) Prior to Novel PCR (1993 to April 2005) Novel PCR (May 2005 to December 2007)
  Coefficient (95% CI) P-value Coefficient (95% CI) P-value Coefficient (95% CI) P-value
Test Positivity   < 0.001*   0.55*   0.003*
1 week lag 0.49 (0.41 to 0.58) < 0.001 0.20 (0.12 to 0.28) < 0.001 0.56 (0.34 to 0.79) < 0.001
2 week lag 0.42 (0.33 to 0.51) < 0.001 0.22 (0.14 to 0.30) < 0.001 0.55 (0.31 to 0.79) < 0.001
3 week lag 0.16 (0.07 to 0.25) < 0.001 0.18 (0.10 to 0.27) < 0.001 0.10 (-0.14 to 0.34) 0.42
4 week lag -0.22 (-0.31 to -0.14) < 0.001 0.07 (-0.01 to 0.16) 0.07 -0.42 (-0.64 to -0.20) < 0.001
Test Volume       
1 week lag 0.02 (0 to 0.04) 0.05 0.01 (-0.01 TO 0.02) 0.52 0.02 (-0.03 to 0.07) 0.41
2 week lag -0.06 (-0.08 to -0.04) < 0.001 -0.02 (-0.04 TO 0.01) 0.08 -0.09 (-0.15 to -0.03) < 0.001
3 week lag 0.03 (0.01 to 0.06) < 0.001 0.01 (-0.01 TO 0.03) 0.48 0.07 (0.01 to 0.13) 0.03
4 week lag 0.01 (0 to 0.03) 0.11 0.00 (-0.01 TO 0.02) 0.68 0.02 (-0.02 to 0.07) 0.27
Test Positivity   < 0.001*   < 0.001*   < 0.001*
1 week lag 1.41 (1.03 to 1.79) < 0.001 0.44 (0.08 TO 0.80) 0.02 1.81 (0.78 to 2.83) < 0.001
2 week lag 0.61 (0.21 to 1.01) < 0.001 0.57 (0.21 TO 0.93) < 0.001 0.94 (-0.15 to 2.02) 0.09
3 week lag -0.05 _0.45 to 0.36) 0.83 0.17 (-0.20 TO 0.53) 0.37 -0.14 (-1.24 to 0.96) 0.81
4 week lag -1.04 (-1.42 to -0.67) < 0.001 -0.20 (-0.56 to 0.16) 0.28 -1.30 (-2.28 to -0.32) 0.01
Test Volume       
1 week lag 0.66 (0.58 to 0.74) < 0.001 0.49 (0.41 to 0.57) < 0.001 0.67 (0.45 to 0.90) < 0.001
2 week lag 0.01 (-0.08 to 0.11) 0.77 0.22 (0.13 to 0.31) < 0.001 -0.15 (-0.41 to 0.12) 0.29
3 week lag 0.25 (0.15 to 0.35) < 0.001 0.12 (0.04 to 0.21) 0.01 0.39 (0.12 to 0.66) 0.01
4 week lag -0.08 (-0.16 to 0) 0.04 0.05 (-0.03 to 0.12) 0.26 -0.11 (-0.30 to 0.09) 0.28
  1. NOTE: CI, confidence interval; * signifies P-value from Granger causality test.