## rel risk & ARR

Regular Contributor
Posts: 168

# rel risk & ARR

Hi All,

I have following dataset. i want relative risk & absolute relative reduction? how can i achieve them using procedure?

data have;

subgrp trt coun;

1     1   72

1     0    8

2     1   74

2     0    6

Want:

rr=(72/80)/(74/80)=0.97

ARR is by newcombe aprroach.

Output for ARR is : 0.03(-.07,0.12)

THanks

Sam

Super User
Posts: 20,765

## Re: rel risk & ARR

Proc Freq - relrisk and riskdiff options, check the documentation for the exact methods/calcuations.

proc freq data=have;

table subgrp*trt/relrisk riskdiff;

weight count;

run;

Regular Contributor
Posts: 168

## Re: rel risk & ARR

Hi Reeza,

i tried both but haven't got the solution

thanks

sam

Super User
Posts: 10,214

## Re: rel risk & ARR

Are you sure ?

```data have;
input subgrp trt count;
cards;
1     1   72
1     0    8
2     1   74
2     0    6
;
run;
proc freq data=have order=data;
table subgrp*trt/relrisk riskdiff;
weight count;
run;
```

Column 1 Risk Estimates

(Asymptotic) 95%         (Exact) 95%

Risk        ASE     Confidence Limits     Confidence Limits

-----------------------------------------------------------------------------

Row 1           0.9000     0.0335     0.8343     0.9657     0.8124     0.9558

Row 2           0.9250     0.0294     0.8673     0.9827     0.8439     0.9720

Total           0.9125     0.0223     0.8687     0.9563     0.8575     0.9513

Difference    -0.0250     0.0446    -0.1125     0.0625

Difference is (Row 1 - Row 2)

Column 2 Risk Estimates

(Asymptotic) 95%         (Exact) 95%

Risk        ASE     Confidence Limits     Confidence Limits

-----------------------------------------------------------------------------

Row 1           0.1000     0.0335     0.0343     0.1657     0.0442     0.1876

Row 2           0.0750     0.0294     0.0173     0.1327     0.0280     0.1561

Total           0.0875     0.0223     0.0437     0.1313     0.0487     0.1425

Difference      0.0250     0.0446    -0.0625     0.1125

Difference is (Row 1 - Row 2)

Statistics for Table of subgrp by trt

Estimates of the Relative Risk (Row1/Row2)

Type of Study                   Value       95% Confidence Limits

-----------------------------------------------------------------

Case-Control (Odds Ratio)      0.7297        0.2412        2.2079

Cohort (Col1 Risk)             0.9730        0.8839        1.0711

Cohort (Col2 Risk)             1.3333        0.4846        3.6686

Xia Keshan

Message was edited by: xia keshan

Regular Contributor
Posts: 168

## Re: rel risk & ARR

TThank you ksharp!!!

now I got the relative risk and 95% ci

but how to calculate ARR(absolute relative reduced)?

expected result for arr:

.03 (-.07,0.12)

thanks

sam

Super User
Posts: 10,214

## Re: rel risk & ARR

Did you see :

Difference      0.0250     0.0446    -0.0625     0.1125

Xia Keshan

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