Question

In a study of the adverse effects of x-rays among children,

a retrospective cohort study was done using records from several large children's hospitals for the period of 1980 to 1985.
10,000 children were selected as a representative population of ill children seen at the hospitals during that time.
Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their
hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263
children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization.
In this retrospective study, which of the following groups are eligible for selection into the study?
A) Children receiving x-rays in 1990
B) Children receiving x-rays in 1975
C) Children receiving x-rays for broken bones in 1983
D) Children in the hospital for cancer treatment in 1985
E) Children who were treated in private clinics and hospitals in 1981

Answer 1

The eligible groups for selection into the study are children receiving x-rays in 1990, children receiving x-rays for broken bones in 1983, and children in the hospital for cancer treatment in 1985.

Step-by-step explanation:

In this retrospective cohort study, the eligible groups for selection into the study are:

• Children receiving x-rays in 1990
• Children receiving x-rays for broken bones in 1983
• Children in the hospital for cancer treatment in 1985

These groups are eligible because the study was done using records from 1980 to 1985, so children receiving x-rays in 1990 and children treated in private clinics and hospitals in 1981 are not within the study period. Children receiving x-rays in 1975 are also not eligible as they are outside the study period.