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Table 2 Estimates of incremental relative risks (IRRs) for bladder cancer of men obtained by three different methods

From: Age adjustment in ecological studies: using a study on arsenic ingestion and bladder cancer as an example

Predictors

Direct Method

Indirect Method

Variable Method

 

IRR [SE]

IRR [SE]

IRR [SE]

Arsenic Exposurea

   

   0.05-0.08 mg/L

-0.029 [0.021]

-0.023 [0.017]

-0.016 [0.010]

   0.09-0.16 mg/L

0.056 [0.030]

0.042 [0.024]

0.022 [0.013]

   0.17-0.32 mg/L

-0.054 [0.039]

-0.031 [0.032]

-0.012 [0.017]

   0.33-0.64 mg/L

0.035 [0.045]

0.021 [0.036]

0.007 [0.020]

   > 0.64 mg/L

0.274 [0.036]

0.228 [0.029]

0.115 [0.016]

Urbanization Indexb

0.167 [0.046]

0.134 [0.037]

0.169 [0.040]

Cigarette Salec

-0.047 [0.104]

-0.026 [0.084]

-0.006 [0.046]

Aged

   

   20-29 years

NAe

NA

0.021 [0.019]

   30-39 years

NA

NA

-0.050 [0.026]

   40-49 years

NA

NA

-0.014 [0.035]

   50-59 years

NA

NA

-0.041 [0.028]

   60-69 years

NA

NA

0.014 [0.028]

   > 69 years

NA

NA

0.037 [0.040]

p Value for the Modelf

< 0.001

< 0.001

< 0.001

  1. aincremental relative risk for each 1% increase in residents exposed to arsenic levels in each exposure category.
  2. bincremental relative risk for each one-unit increase in urbanization index.
  3. cincremental relative risk for each 100 cigarettes sold per year.
  4. dincremental relative risk for each 1% increase in residents in each age group.
  5. enot included in the analyses.
  6. fp value for F test of the significance of the model.