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Table 3 Mixed effects Cox model results of smoke exposure during gestational periods at the 25% exposure threshold, in all eligible children and stratified by sex. Models are adjusted for birth season, birthyear and, where applicable, sex, with a random intercept for Metropolitan statistical Area (MSA). The first and second N values correspond to the entire cohort (full cohort) and the cohort portion whose gestational age estimate was available to estimate wildfire smoke-day exposure (GA sub-cohort), respectively. All exposures are the average weekly number of smoke-days in the given period. RX = prescribed medication claim; ‘25% exposure threshold’ refers to population-weighted percentage of zip codes, here 25%, within an MSA required to experience a smoke-day, in order to assign a smoke-day to the MSA

From: Wildfire smoke exposure and early childhood respiratory health: a study of prescription claims data

   

All children (N = 182,387 / 113,154)

Male children (N = 93,321 / 57,682)

Female children (N = 89,066 / 55,472)

Likelihood ratio test

p-value

Outcome

Cohort

Exposure

HR (95% CI)

HR (95% CI)

HR (95% CI)

 

Upper respiratory RX

Full cohort

     
  

T1

1.082 (0.985, 1.188)

1.026 (0.902, 1.167)

1.140 (0.997, 1.303)

0.06

  

T2

0.978 (0.876, 1.093)

1.079 (0.935, 1.245)

0.857 (0.722, 1.018)

0.13

  

T3

0.913 (0.821, 1.014)

0.884 (0.766, 1.020)

0.948 (0.812, 1.107)

0.67

Upper respiratory RX

GA sub-cohort

     
  

T1

1.094 (0.974, 1.229)

1.066 (0.910, 1.249)

1.121 (0.949, 1.324)

0.23

  

T2

0.935 (0.806, 1.085)

0.978 (0.806, 1.186)

0.882 (0.701, 1.108)

0.51

  

T3

0.948 (0.833, 1.080)

0.957 (0.804, 1.140)

0.931 (0.770, 1.127)

0.94

Lower respiratory RX

Full cohort

     
  

T1

0.977 (0.951, 1.003)

0.960 (0.927, 0.993)

0.997 (0.956, 1.039)

0.48

  

T2

0.986 (0.957, 1.017)

0.987 (0.949, 1.027)

0.978 (0.933, 1.026)

0.65

  

T3

0.992 (0.966, 1.019)

1.004 (0.969, 1.040)

0.970 (0.930, 1.012)

0.06

Lower respiratory RX

GA sub-cohort

     
  

T1

0.966 (0.935, 0.999)

0.959 (0.918, 1.002)

0.969 (0.920, 1.021)

0.70

  

T2

0.968 (0.930, 1.008)

0.966 (0.917, 1.018)

0.962 (0.903, 1.025)

0.79

  

T3

0.972(0.939, 1.005)

0.982 (0.940, 1.027)

0.948 (0.899, 1.000)

0.17

Systemic Anti-inflam. RX

Full cohort

     
  

T1

0.976 (0.948, 1.005)

0.978 (0.941, 1.016)

0.973 (0.929, 1.018)

0.98

  

T2

0.968 (0.935, 1.001)

0.967 (0.925, 1.010)

0.967 (0.916, 1.020)

0.72

  

T3

0.996 (0.966, 1.027)

1.008 (0.968, 1.049)

0.975 (0.930, 1.022)

0.90

Systemic Anti-inflam. RX

GA sub-cohort

     
  

T1

0.962 (0.927, 0.997)

0.959 (0.914, 1.006)

0.963 (0.910, 1.019)

0.46

  

T2

0.946 (0.905, 0.989)

0.921 (0.869, 0.976)

0.982 (0.917, 1.053)

0.15

  

T3

0.989 (0.953, 1.027)

1.024 (0.975, 1.075)

0.935 (0.882, 0.992)

0.36