Question

The results of a matched case control study performed during a Echovirus outbreak in Germany in 2001 are provided in the table below. The study hypothesis was that swimming in a specific pond (pond A) was suspected of increasing the risk of aseptic meningitis due to an Echovirus. In the study, each case was matched to a single control, therefore constituting a matched pair. What is the Unmatched OR for this study? Round to 2 decimal places. ontrols Exposed to Pond Unexposecd ほ礼29 240 Unexposed 6 200 75 275 Total

Answer 1

First of all we need to construct 2×2 contingency unmatched table.

It is as below

	Cases	controls	Total
Exposed to pond A	194+46=240(a)	194+6=200(b)	440
Unexposed	6+29=35(c)	29+46=75(d)	110
Total	275	275	550

Unmatched OR formula = ad/bc

=240×75/200×35

=18000/7000

=2.57142857

Rounding into 2 decimal place= 2.57