Exercise 8:    Interaction tests

·         This exercise will use demo2 project. If you have not started demo2 project, click here to follow exercise 1: start the new project demo2

·         This exercise will use new variables. Click here to follow through Exercise 2:  Create new variables, code and label variables, if you have not done so.

Objectives:

·         Create interaction tests table 1

·         Create interaction tests table 2

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Objective 1: To create following table:

Interactions test 1

Cigarette smoking ->

N

No

Yes

Total

P(Interaction)

SBP

Crude

788

0.5 (-0.3, 1.4) 0.234

-0.5 (-1.7, 0.6) 0.369

0.2 (-0.5, 0.8) 0.652

0.155

Adjusted

784

1.0 ( 0.2, 1.7) 0.012

0.4 (-0.6, 1.5) 0.413

0.8 (0.2, 1.4) 0.012

0.430

DBP

Crude

788

0.3 (-0.1, 0.7) 0.138

-0.4 (-1.0, 0.2) 0.173

0.1 (-0.3, 0.4) 0.672

0.049

Adjusted

784

0.4 ( 0.0, 0.8) 0.034

-0.1 (-0.7, 0.5) 0.772

0.3 (-0.1, 0.6) 0.117

0.140

ß (95%CI) p-value / OR/RR (95%CI) p-value
Outcome: SBP and DBP
Risk factor: Body mass index
Crude: none adjustment
Adjusted: adjust for AGE, SEX, Education, Occupation and Alcohol consumption
P(interaction) were from log likelihood ratio test comparing two nested models

Follow following steps to create the above table:

·         Click “Advanced analysis” -> “Interactions test”

·         Drag and drop variable SBP and DBP to “Select outcome variables (Y)”

·         Drag and drop BMI to “Select risk factors(X)”

·         Drag and drop AGE, SEX, EDUC, OCCU and ALH to “Model 2 (Adjusted)”.

·         Drag and drop SMK to “Select effect modifier (categorical)”

·         Set rows sorted by “Y: Outcomes” then “M: Models” and then “X: Exposures”

 

  

 

·         Click “View Table” button, wait for a few seconds, you will get the above table

 

Done!

Objective 2: To create following table:

Interactions test 2

SNP marker I

Cigarette smoking

N

Mean+SD

beta

95%CI

P value

P (interaction)

SBP

AA

No

311

126.3 + 20.9

0

0.288

AA

Yes

194

129.5 + 23.1

-6.4

-10.9, -2.0

0.005

AB

No

158

132.1 + 23.4

6.5

2.7, 10.3

<0.001

AB

Yes

109

137.6 + 24.6

4.9

-0.2, 9.9

0.058

BB

No

15

137.7 + 13.4

11.6

1.5, 21.6

0.024

BB

Yes

23

140.3 + 21.5

7.5

-1.3, 16.4

0.096

DBP

AA

No

311

68.5 + 10.1

0

0.257

AA

Yes

194

69.2 + 10.5

-1.4

-3.9, 1.0

0.252

AB

No

158

69.4 + 12.2

1.1

-0.9, 3.2

0.283

AB

Yes

109

72.1 + 15.0

2.4

-0.3, 5.2

0.086

BB

No

15

70.8 + 7.2

2.0

-3.5, 7.6

0.476

BB

Yes

23

72.0 + 10.1

2.4

-2.4, 7.3

0.326

Outcome: SBP and DBP
Risk factor: SNP marker I by Cigarette smoking
Adjust for: AGE, Body mass index, SEX, Education, Occupation and Alcohol consumption
P(interaction) were from log likelihood ratio test comparing two nested models

Follow following steps to create the above table:

·         Click “Advanced analysis” -> “Interactions test”

·         Drag and drop variable SBP and DBP to “Select outcome variables (Y)”

·         Drag and drop SNP1 to “Select risk factors(X)”

·         Drag and drop AGE, BMI, SEX, EDUC, OCCU and ALH to “Model 1”.

·         Drag and drop SMK to “Select effect modifier (categorical)”

·         Set rows sorted by “Y: Outcomes” then “X: Exposures”.

             

·         Click “View Table” button, wait for a few seconds, you will get the above table

 

Done!