Chapter 12, Problem 1RQ

Summary Introduction

To calculate: The relative risk for thyroid tumors.

Introduction: The relative risk is the ratio between risk in exposed to the risk in unexposed. It also defined as “the probability of an event ocuuring in exposed people compared with the probabilty of the event in unexposed people”.

Explanation of Solution

As per the given data the following table can be constructed:

Radiation therapy	Benign thyroid tumor	No tumor	Total	incidence
Received	52 (a)	2820 (b)	2872 (a+b)	a/(a+b)
Unrecived	6 (c)	5049 (d)	5055 (c+d)	c/(c+d)

The relative risk is calculated as follows:

$\begin{array}{c}\text{Relative}\text{=}\frac{\frac{\text{a}}{\text{a+b}}}{\frac{\text{c}}{\text{c+d}}}\\ \text{=}\frac{\frac{52}{\text{52+2820}}}{\frac{6}{\text{6+5049}}}\\ =\frac{\frac{52}{\text{2872}}}{\frac{6}{\text{5055}}}\\ =15.3\end{array}$

Therefore, the relative risk for thyroid tumors is 15.3.

Conclusion

As per the given data, the relative risk for thyroid tumors is 15.3.