For sample adults aged 40 years or older, COLEV indicates whether the respondent ever had a colonoscopy.
Beginning in 2019, the variable COLSIGEV indicates whether or not the person had a colonoscopy or sigmoidoscopy. IPUMS NHIS staff constructed COLSIGEV for 2010, 2013, 2015, and 2018 using information from SIGEV and COLEV to have a comparable indicator for whether someone had a colonoscopy or sigmoidoscopy.
2010, 2013, 2015, and 2018
The survey form directed interviewers to read if necessary, "A polyp is a small growth that develops on the inside of the colon or rectum. Before these tests, you are asked to take a medication that causes diarrhea."
According to the 2010 and forward Field Representative's Manual, this and related questions were asked:
...to determine the practices and knowledge of the public with regard to cancer screening practices. This includes practices that are known to reduce mortality from cancer and some for which evidence of effectiveness is not available. The 2010 Cancer Screening Supplement will be the first time questions about having a breast MRI, virtual colonoscopy, and lung x-ray are in the NHIS.
The 2010 and forward Manual further provided the following definition for cancer:
A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissue and can spread through the bloodstream and lymphatic system to other parts of the body.
The Manual also provided the following statement regarding how the data from the Cancer Screening questions would be used:
. . . It also allows for comparisons among subgroups of the population to examine factors that may influence . . . cancer screening exam practices. Together, this information will be useful in developing public health and health services programs to increase . . . the use of regular and effective screening.
The 2015 sample layout file provides the following explanation:
There are several different kinds of tests to check for colon cancer. Colonoscopy (colon-OS-copy) and sigmoidoscopy (sigmoid-OS-copy) are exams in which a doctor inserts a tube into the rectum to look for polyps or cancer. For a colonoscopy, the doctor checks the entire colon, and you are given medication through a needle in your arm to make you sleepy, and told to have someone drive you home. For a Sigmoidoscopy, the doctor checks only part of the colon and you are fully awake.