Chapter 18, Problem 1RQ

Summary Introduction

Introduction: In epidemiology, incidence or incidence rate is the measure that is used to express the probability of occurrence of medical condition within a specific period of time in a given population.

Answer to Problem 1RQ

Correct answer: “Incidence rate of cancer Z in the country will increase during the first year of the program”. Hence, the correct answer is option a.

Explanation of Solution

Reason for the correct answer:

In a certain country, a new program was instituted and the program used a screening test that is effective in detecting cancer Z in the early stage. It was assumed that there is no proper treatment for this cancer, and the program results in no change in the usual course of disease. It was also assumed that the rates noted are calculated from all known cases of cancer Z. There is no variation in the quality of the death certification of the cancer.

$\text{Incidence}\text{rate}\text{=}\frac{\text{No}\text{.}\text{}\text{of}\text{}\text{new}\text{cases}\text{}\text{}\text{}\text{of}\text{a}\text{disease}\text{occurring}\text{in}\text{a}\text{population}\text{during}\text{a}\text{specific}\text{period}\text{of}\text{time}}{\text{Total}\text{person}\text{time}}$

The new screening program detects cancer Z in the initial period, and the incidence rate will gradually increase in the first year. This is because the screening program of the initial year voluntaries has number of cancer patients for screening. After that, the incidence rate might decrease due to the death or other factors, as there was no change in the usual course of disease.

Option a. is given as “Incidence rate will increase”. Incidence rate of cancer Z in the country will increase for new screening program during the first year.

Hence, the correct answer is option a.

Reasons for incorrect answers:

Option b. is given as “Incidence rate will decrease”.

The incidence rate increases during the first year and only decreases gradually in the subsequent years.

Hence, option b. is incorrect.

Option c. is given as “Incidence rate will remain constant”.

The incidence rate will not remain the same, but increases during the first year and decreases gradually in the subsequent years because the people in the country are already suffering with cancer and there is no effective treatment for the disease. Hence, option c. is incorrect.

Hence, options b. and c. are incorrect.

Conclusion

Incidence rate of cancer Z in the country will increase for new screening program during the first year.