Chapter 5, Problem 1RQ

Summary Introduction

Introduction: Understanding transmission and development of disease is an important part to provide appropriate effective health care to patients. Assessing the validity and reliability of the performed diagnostic and screening tests are important to distinguish between people of a particular population who have the disease and those who do not.

Answer to Problem 1RQ

Correct answer: “The sensitivity of the physical examination was: 72.0%.”

Explanation of Solution

As given in the problem statement, a physical examination was used to screen for breast cancer. For the study, they have selected 2500 women with biopsy-proven adenocarcinoma of the breast, 5000 age-matched controls, and race-matched control women. A mass of palpation shows the results were positive in 1800 cases and 800 control women showed no evidence of cancer at biopsy.

The ability of a test to identify correctly the persons who have disease is called as sensitivity of the test.

The true characteristics in the population as the given study are as follows:

Positive	1800 (TP)	800 (FP)	2600
Negative	700 (FN)	4200 (TN)	4900
Total	2500	5000	7500

$\begin{array}{c}\text{Sensitivity of the test =}\frac{\text{True positive}\text{(TP)}}{\text{True positive (TP) +false positive}\text{(FP)}}\\ =\frac{1800}{1800+700}=\frac{1800}{2500}\\ =0.72\times 100\\ =72\%\end{array}$

Therefore, the sensitivity of the physical examination was: 72.0%.