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Colorectal cancer-screening tests and associated health behaviors
Colorectal Cancer–Screening Tests and Associated Health Behaviors Jean A. Shapiro, PhD, Laura C. Seeff, MD, Marion R. Nadel, PhD, MPH Background: Studies have shown that screening reduces colorectal cancer mortality. We analyzed national survey data to determine rates of use of fecal occult blood testing (FOBT) and sigmoidoscopy, and to determine if these rates differ by demographic factors and other health behaviors. Methods:
A total of 52,754 respondents aged ⱖ50 years were questioned in the 1997 Behavioral Risk Factor Surveillance System (BRFSS) survey (a random-digit-dialing telephone survey of the non-institutionalized U.S. population) about their use of FOBT and sigmoidoscopy.
Results:
The age-adjusted proportion of respondents who reported having had a colorectal cancer screening test during the recommended time interval (past year for FOBT and past 5 years for sigmoidoscopy) was 19.8% for FOBT, 30.5% for sigmoidoscopy, and 41.1% for either FOBT or sigmoidoscopy. Rates of use of colorectal cancer screening tests were higher for those who had other screening tests (mammography, Papanicolaou smear, and cholesterol check). There were also differences in rates of use of colorectal cancer screening tests according to other health behaviors (smoking, seat belt use, fruit and vegetable intake, and physical activity) and several demographic factors. However, none of the subgroups that we examined reported a rate of FOBT use above 29% within the past year or a rate of sigmoidoscopy use above 41% within the past 5 years.
Conclusions: While rates of use of FOBT and sigmoidoscopy were higher among people who practiced other healthy behaviors, rates of use were still quite low in all subgroups. There is a need for increased awareness of the importance of colorectal cancer screening. Medical Subject Headings (MeSH): colorectal neoplasms, mass screening, occult blood, sigmoidoscopy (Am J Prev Med 2001;21(2):132–137) © 2001 American Journal of Preventive Medicine
Introduction
C
olorectal cancer is the second leading cause of cancer death in the United States, following lung cancer.1 According to the American Cancer Society (ACS), there will be approximately 135,400 new cases of colorectal cancer in 2001 and approximately 56,700 deaths due to the disease.1 There is now strong evidence that screening can reduce colorectal cancer mortality. Several randomized controlled trials have shown that the fecal occult blood test (FOBT) can reduce colorectal cancer mortality.2– 4 Several case– control studies found that sigmoidoscopy was associated with reduced risk of colorectal cancer mortality.5–7 Based on this evidence, there is now consensus among medical organizations that screening
From the Division of Cancer Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia Address correspondence and reprint requests to: Jean A. Shapiro, PhD, Centers for Disease Control and Prevention, NCCDPHP, DCPC, Mailstop K-55, 4770 Buford Hwy NE, Atlanta, GA 30341-3717.
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is effective in reducing colorectal cancer mortality. Screening is recommended by several major organizations, including the U.S. Preventive Services Task Force (USPSTF) and the ACS.8,9 We analyzed data from the 1997 Behavioral Risk Factor Surveillance System (BRFSS) to determine the rates of use of FOBT and sigmoidoscopy, and to determine if these rates differ by demographic factors and other health behaviors.
Methods The BRFSS is a state-based, random-digit-dialing telephone survey of the non-institutionalized U.S. population aged ⱖ18 years. In 1997, all 50 states, the District of Columbia, and Puerto Rico participated in the BRFSS. The median state response rate for the entire survey was 76.5%, calculated as the percentage of eligible respondents successfully contacted who completed the telephone interview. A response rate was also calculated according to a formula developed by the Council of American Survey Research Organizations, which assigns phone numbers with unknown eligibility status as eligible in the same proportion as among all phone numbers
Am J Prev Med 2001;21(2) 0749-3797/01/$–see front matter © 2001 American Journal of Preventive Medicine • Published by Elsevier Science Inc. PII S0749-3797(01)00329-4
of known status.10 The median state response rate according to this formula was 62.1%. Survey respondents aged ⱖ40 years were asked about both the blood stool test and sigmoidoscopy/proctoscopy. While these tests can be used for both screening and diagnosis, the survey questions were not asked in a manner that allowed the respondents to identify the indication for the test. We use the term “colorectal cancer screening tests” here to refer to these tests regardless of their indication, as these tests are often used for screening. For the blood stool test or FOBT, the respondents were told: “A blood stool test is a test that may use a special kit at home to determine whether the stool contains blood.” They were then asked if they had ever had this test using a home kit and, if so, when they had their last blood stool test using a home kit. In 1997 for the first time, the BRFSS questions about FOBT specified that the test used a home kit. Previous BRFSS survey questions did not address whether stool samples were obtained at home using a kit or as part of a digital rectal examination. The recommended method of obtaining a stool sample for an FOBT is through use of the home kit.8,11,12 Use of the home kit allows for collection of multiple samples and should be performed in conjunction with dietary restrictions to decrease the possibility of false-positive or false-negative results from certain foods and medications.11,12 For sigmoidoscopy/proctoscopy, respondents were told: “A sigmoidoscopy or proctoscopy is when a tube is inserted in the rectum to view the bowel for signs of cancer and other health problems.” They were then asked if they had ever had this examination and, if so, when they had their last sigmoidoscopy or proctoscopy. While the use of the term “proctoscopy” is inconsistent in the literature, the term is usually used to refer to the rigid sigmoidoscopy, a test that uses a rigid instrument shorter than the instrument used for flexible sigmoidoscopy. For colorectal cancer screening, flexible sigmoidoscopy is currently recommended rather than rigid sigmoidoscopy. For the purpose of this discussion, sigmoidoscopy/proctoscopy will hereafter be referred to as sigmoidoscopy. For our analysis, we included only respondents aged ⱖ50 years, because it is recommended that colorectal cancer screening be initiated at age 50 for average-risk people who do not have a family history of the disease or certain other risk factors.8,9,11 All of our analyses refer to tests within the most commonly recommended time intervals: during the past year for FOBT and during the past 5 years for sigmoidoscopy. All respondents were also asked questions about demographics, race, healthcare coverage, cholesterol screening, seatbelt use, and cigarette smoking. Women were asked about use of mammography and Papanicolaou (Pap) smears. Respondents in 11 states were asked about fruit and vegetable consumption, and respondents in 12 states were asked about physical activity. A total of 52,754 respondents aged ⱖ50 years were questioned about use of FOBT and sigmoidoscopy. Respondents who refused to answer a question or who did not know the answer to a question were excluded from analyses of that specific question. The total number of respondent refusals or unknowns was 1328 (2.5%) for the FOBT questions and 1658 (3.1%) for the sigmoidoscopy questions. For the other variables in Tables 1 and 2, the total number of respondent refusals or unknowns was ⬍4% for all variables except income
(20%) and fruit and vegetable servings (10%). To minimize the amount of missing data in analyses of each specific variable, we excluded only respondents who were missing data on the specific variables included in each analysis and did not exclude respondents who were missing data for other variables. The data were weighted to the respondent’s probability of selection and to the race-, age-, and gender-specific population from the most current census data for each state. Proportions and standard errors were calculated using SAS13 and SUDAAN,14 a statistical package for analyzing complex survey data. All proportions were adjusted for age in 5-year groups, using the BRFSS population as the standard population. Logistic regression in SUDAAN was used to calculate odds ratios (ORs) and 95% confidence intervals. All OR estimates are presented adjusted for age, gender (except for mammography and Pap smear use), education, and healthcare coverage using the categories presented in Table 1.
Results The age-adjusted proportion of respondents who reported having a colorectal cancer screening test during the recommended time interval was 19.8% for FOBT, 30.5% for sigmoidoscopy, and 41.1% for either FOBT or sigmoidoscopy (Table 1). A total of 9.5% reported having both tests during the recommended time intervals. Rates of use of colorectal cancer screening tests by demographic factors have been reported previously unadjusted for age15 and are presented age adjusted in Table 1. The rates of FOBT use were ⬍25% in all of the demographic subgroups that we examined, ranging from 9.5% for people without healthcare coverage to 24.0% for people with incomes of ⱖ$50,000. For sigmoidoscopy, rates were ⬍41% in all of the demographic subgroups we examined, ranging from 18.8% for people without healthcare coverage to 40.6% for people with incomes of ⱖ$50,000. Women were slightly more likely than men to report having an FOBT, but men were slightly more likely to report having a sigmoidoscopy. Asian/Pacific Islanders and American Indians/Alaska Natives were less likely to report having a colorectal cancer–screening test than blacks or whites. However, the sample size for racial groups other than blacks and whites was fairly small. People of Spanish or Hispanic origin were less likely to report having a colorectal cancer–screening test. Reported use of colorectal cancer–screening tests increased with increasing educational level and income. People without healthcare coverage were less likely than those with healthcare coverage to report having colorectal cancer– screening tests. Reported use of colorectal cancer– screening tests increased with each decade of age from ages 50 to 59 through ages 70 to 79, and then decreased for the group aged ⱖ80. Table 2 presents age-adjusted rates of use of colorectal cancer–screening tests by other health behaviors. The largest differences in rates of use of colorectal Am J Prev Med 2001;21(2)
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Table 1. FOBT and sigmoidoscopy by demographic factors, Behavioral Risk Factor Surveillance System (BRFSS), 1997
FOBT within past year Characteristic Total (50,490b) Gender Male Female Race White Black Asian/Pacific Islander American Indian/Alaska Native Other Spanish or Hispanic origin No Yes Age (years) 50–59 60–69 70–79 ⱖ80 Education ⬍12 years High school graduate Some college/technical school College graduate Income (annual household) ⬍$20,000 $20,000–35,000 $35,000–50,000 ⱖ$50,000 Healthcare coverage No Yes
b
Sigmoidoscopy within past 5 years
Either test within recommended time intervala
%c
(95% CI)
%c
(95% CI)
%c
(95% CI)
19.8
(19.3–20.3)
30.5
(29.9–31.1)
41.1
(40.4–41.8)
19583 30907
18.8 20.8
(17.9–19.6) (20.1–21.5)
35.7 26.5
(34.7–36.8) (25.8–27.2)
44.5 38.6
(43.4–45.5) (37.7–39.4)
44736 3511 723 520 784
20.1 20.4 12.3 14.2 14.0
(19.5–20.7) (18.4–22.4) (8.4–16.2) (9.3–19.0) (10.4–17.7)
31.0 29.9 26.7 26.3 19.7
(30.3–31.6) (27.7–32.2) (20.5–32.8) (19.6–33.0) (15.5–24.0)
41.6 40.7 35.1 34.7 27.7
(40.9–42.3) (38.3–43.1) (28.3–42.0) (27.8–41.7) (22.8–32.5)
47855 2416
20.3 13.7
(19.7–20.8) (11.6–15.7)
30.8 26.6
(30.2–31.4) (23.6–29.6)
41.6 33.7
(40.9–42.3) (30.6–36.9)
18333 14835 12247 5075
15.5 21.8 23.7 20.1
(14.6–16.3) (20.8–22.8) (22.5–24.8) (18.4–21.8)
23.6 33.2 37.0 31.6
(22.6–24.6) (32.0–34.4) (35.7–38.3) (29.7–33.6)
33.1 44.0 48.8 42.0
(32.1–34.2) (42.8–45.2) (47.5–50.2) (39.9–44.0)
10300 17636 11677 10744
15.4 19.2 21.1 23.8
(14.3–16.5) (18.3–20.1) (19.9–22.2) (22.6–25.1)
26.2 28.0 31.9 37.9
(24.8–27.6) (27.0–29.0) (30.6–33.2) (36.5–39.4)
35.1 38.6 43.6 48.6
(33.6–36.6) (37.5–39.7) (42.2–44.9) (47.1–50.1)
13448 12678 6487 8356
15.6 19.7 22.0 24.0
(14.7–16.5) (18.6–20.7) (20.3–23.7) (22.1–25.8)
25.3 30.1 33.6 40.6
(24.1–26.5) (28.9–31.3) (31.6–35.5) (38.5–42.7)
34.2 40.7 44.5 50.9
(32.9–35.5) (39.4–42.0) (42.6–46.5) (48.8–53.1)
3248 47191
9.5 20.5
(7.4–11.6) (20.0–21.1)
18.8 31.3
(15.6–22.0) (30.7–31.9)
24.2 42.2
(20.7–27.6) (41.5–42.9)
n
a
Respondents who had either an FOBT within the past year or a sigmoidoscopy within the past 5 years. Number who answered both the FOBT and sigmoidoscopy questions. Number who answered either the FOBT questions or the sigmoidoscopy questions may be slightly higher. For some variables, the numbers do not add up to the total because of missing data. c All percentages are adjusted for age. CI, confidence interval; FOBT, fecal occult blood test b
cancer–screening tests were between those who reported using other screening tests (e.g., mammogram, Pap smear, and cholesterol check) and those who did not. Women who reported having a mammogram or Pap smear within the past year and people who reported having a cholesterol check within the past 2 years were much more likely to report having an FOBT or sigmoidoscopy. People who had not had their cholesterol checked in the past 2 years had the lowest screening rates of all the subgroups we examined (6.4% for FOBT and 15.3% for sigmoidoscopy). There were also differences in rates according to other health behaviors. Current smokers were less likely than either former or never smokers to report use of FOBT or sigmoidoscopy. People who used seat belts were more likely to report use of these tests, as were people who ate more fruits and vegetables or who were physically active. Table 3 presents ORs for the association of selected 134
health behaviors with FOBT and sigmoidoscopy, adjusted for age, gender, education, and healthcare coverage. The relationships seen in Table 2 persisted after adjustment for these factors. Use of mammography, Pap smears, and cholesterol checks was strongly associated with use of FOBT and of sigmoidoscopy. Seat belt use, greater fruit and vegetable intake, and physical activity were also associated with use of colorectal cancer–screening tests. Current smoking was inversely associated with use of colorectal cancer–screening tests.
Discussion Our results from the 1997 BRFSS, a survey that included more than 50,000 respondents aged ⱖ50 years in all U.S. states, indicate that self-reported rates of use of colorectal cancer–screening tests are uniformly low. The USPSTF, ACS, and other organizations recommend the use of FOBT and/or flexible sigmoidoscopy
American Journal of Preventive Medicine, Volume 21, Number 2
Table 2. FOBT and sigmoidoscopy by other health behaviors, Behavioral Risk Factor Surveillance System (BRFSS), 1997 Sigmoidoscopy within past 5 years
FOBT within past year Characteristic Mammogram within past year No Yes Pap smear within past year No Yes Cholesterol check within past 2 years No Yes Cigarette smoking status Never Former Current Seatbelt use Never or seldom Sometimes Always or nearly always Daily fruit and vegetable servingsc ⬍2 2–4 5⫹ Physical activityd None Irregular Regular
na
%b
(95% CI)
%b
(95% CI)
12942 17716
10.0 28.3
(9.2–10.8) (27.3–29.3)
16.7 33.4
(15.7–17.7) (32.4–34.5)
13849 16441
11.8 28.7
(11.0–12.6) (27.6–29.7)
19.8 32.6
(18.8–20.8) (31.5–33.7)
10297 38496
6.4 23.4
(5.7–7.2) (22.8–24.0)
15.3 34.6
(14.2–16.5) (33.9–35.3)
24345 17405 8592
20.4 21.3 14.1
(19.7–21.2) (20.4–22.2) (12.8–15.4)
29.4 34.3 25.2
(28.5–30.3) (33.2–35.3) (23.5–26.8)
3379 3216 43492
11.8 13.8 20.8
(10.1–13.4) (11.9–15.8) (20.2–21.3)
24.2 24.6 31.4
(21.9–26.5) (22.3–26.9) (30.8–32.1)
610 5304 2754
13.5 18.0 25.5
(9.5–17.4) (16.5–19.5) (23.1–27.9)
26.8 29.4 33.4
(21.3–32.4) (27.7–31.1) (30.9–35.9)
4274 2578 4180
16.7 19.5 24.4
(15.0–18.3) (17.2–21.9) (22.3–26.4)
25.2 26.8 35.6
(23.4–27.0) (24.3–29.4) (33.3–37.8)
a
Number who answered both the FOBT and sigmoidoscopy questions. Number who answered either the FOBT questions or the sigmoidoscopy questions may be slightly higher. b All percentages are adjusted for age. c Only 11 states asked the questions about fruits and vegetables. d Physical activity in leisure time. Only 12 states asked the questions about physical activity. Regular physical activity was defined as any physical activity reported at least three times per week for at least 20 minutes each time. CI, confidence interval; FOBT, fecal occult blood test
for screening average-risk people aged ⱖ50 years,8,9,11 but we found that only about 20% of respondents reported an FOBT within the past year and only about 30% reported a sigmoidoscopy within the past 5 years. No subgroup that we examined reported a rate of FOBT use within the past year above 29% or a rate of sigmoidoscopy use within the past 5 years above 41%. Medical organizations differ on whether they recommend use of FOBT or flexible sigmoidoscopy alone or that both tests be performed.8,9,11 We found that about 41% of respondents reported having either FOBT within the past year or sigmoidoscopy within the past 5 years, while only about 10% reported having both tests within these recommended time intervals. The reported rates of colorectal cancer screening are much lower than for other widely recommended cancer screening tests. For example, data from the 1997 BRFSS indicate that only about 39% of women aged ⱖ50 years reported having either FOBT or sigmoidoscopy within the recommended time interval, while about 60% of these women reported having a mammogram within the past year and about 56% reported having a Pap smear within the past year. Rates of colorectal cancer screening may be lower because
widespread consensus about the value of screening has been reached only recently. Although ACS has recommended both FOBT and sigmoidoscopy since 1980,16 the USPSTF did not recommend these screening tests until 1996.9 The evidence for the benefit of colorectal cancer screening was strengthened with the publication of findings from several well-designed studies—two case– control studies of sigmoidoscopy in 19925,6 and the first randomized controlled trial of FOBT in 19932—suggesting that screening reduced colorectal cancer mortality. We found that use of sigmoidoscopy and FOBT increased with increasing educational level and income and that Hispanics were less likely to use these tests. These results are similar to results from the 1987 and 1992 National Health Interview Surveys (NHIS), inperson household interviews of the U.S. civilian, noninstitutionalized population.17–19 Results for age and for race have been inconsistent.17–19 There is very little data on the association between colorectal cancer screening tests and other health behaviors. The 1987 NHIS found that there was no association between current smoking and FOBT or proctoscopy.17 A 1995 survey of women enrolled in Am J Prev Med 2001;21(2)
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Table 3. Association of selected health behaviors with FOBT and sigmoidoscopy, Behavioral Risk Factor Surveillance System (BRFSS), 1997 FOBT within past year Characteristic
ORa (95% CI)
Mammogram within past year No 1.0 (reference) Yes 3.4 (3.1–3.8) Pap smear within past year No 1.0 (reference) Yes 2.9 (2.7–3.2) Cholesterol check within past 2 years No 1.0 (reference) Yes 4.3 (3.8–4.9) Cigarette smoking status Never 1.0 (reference) Former 1.1 (1.0–1.2) Current 0.7 (0.6–0.8) Seat-belt use Never or seldom 1.0 (reference) Sometimes 1.2 (1.0–1.6) Always or nearly 1.8 (1.5–2.2) always Daily fruit and vegetable servingsb ⬍2 1.0 (reference) 2–4 1.3 (0.9–1.9) 5⫹ 2.0 (1.4–2.9) Physical activityc None 1.0 (reference) Irregular 1.2 (1.0–1.4) Regular 1.5 (1.3–1.8)
Sigmoidoscopy within past 5 years ORa (95% CI) 1.0 (reference) 2.4 (2.2–2.7) 1.0 (reference) 1.9 (1.7–2.1) 1.0 (reference) 2.8 (2.6–3.1) 1.0 (reference) 1.1 (1.1–1.2) 0.8 (0.7–0.9) 1.0 (reference) 1.1 (0.9–1.3) 1.5 (1.3–1.7) 1.0 (reference) 1.1 (0.8–1.5) 1.3 (1.0–1.8) 1.0 (reference) 1.0 (0.9–1.2) 1.5 (1.3–1.7)
a
All odds ratios are adjusted for age, gender (except for mammography and Pap smear use), education, and health care coverage. Only 11 states asked the questions about fruits and vegetables. c Physical activity in leisure time. Only 12 states asked the questions about physical activity. Regular physical activity was defined as any physical activity reported at least three times per week for at least 20 minutes each time. CI, confidence interval; FOBT, fecal occult blood test; OR, odds ratio b
Group Health Cooperative, a health maintenance organization in Washington state, found that current smokers were less likely than former or never smokers to report an FOBT within the past 5 years.20 In the Group Health Cooperative survey, women who reported a recent mammogram also were more likely to report an FOBT within the past 5 years.20 In our analysis of the 1997 BRFSS, people who practiced other healthy behaviors were more likely to have had colorectal cancer screening tests. In particular, use of other screening tests (mammography within the past year, Pap smear within the past year, and cholesterol check within the past 2 years) was strongly associated with use of colorectal cancer screening tests within the recommended time intervals (past year for FOBT and past 5 years for sigmoidoscopy). Possible reasons for the strong associations of colorectal cancer screening tests with these other screening tests include interest of the patient or the healthcare provider in screening and the 136
fact that these tests usually involve a visit to a healthcare provider. A visit to the healthcare provider for one screening test may provide an opportunity for the provider to recommend or perform another screening test. However, rates of use of colorectal cancer screening tests in our study were still quite low, even among people who had recently undergone other screening tests. Our finding of an association between use of colorectal cancer screening tests and other health behaviors is consistent with results from studies of other cancer screening tests. For example, use of mammography has been associated with health behaviors such as engaging in regular exercise, being a nonsmoker, having Pap smear screening, using seat belts, and having dental checkups.21–23 There are several limitations to this analysis. Because the BRFSS is a telephone survey, the results may not be generalizable to people without telephones. However, the vast majority (approximately 95%) of U.S. households have telephones.24 Another limitation is that 23.5% of the eligible respondents who were successfully contacted did not complete the telephone interview. Results for colorectal cancer screening rates may be biased if the respondents’ rates of use of colorectal cancer screening tests were substantially different from the nonrespondents’ rates. In addition, we were unable to distinguish between tests done for screening and tests done for diagnosis. If some of these tests were done for diagnostic purposes, the rate of use of these tests for screening would be lower than reported here. Some respondents may also have incorrectly reported their use of colorectal cancer screening tests or other information in the survey. In particular, information about colonoscopies or barium enemas may have been included in responses to the question about sigmoidoscopy. However, studies that compared self-report of colorectal cancer screening to information from medical records have generally found moderate to good agreement between the two data sources.20,25–28 The 1997 BRFSS did not explicitly ask about use of colonoscopy or barium enema, which may be used for colorectal cancer screening. However, these procedures were probably infrequently used for screening in 1997. Before 1997, no major guidelines recommended colonoscopy or barium enema for screening of people not at high risk for colorectal cancer. The USPSTF did not recommend any colorectal cancer screening tests until 1996, when it published guidelines recommending FOBT and/or sigmoidoscopy, but concluded that there was insufficient evidence to recommend barium enema or colonoscopy.9 Data from a 1999 –2000 national survey of primary care physicians indicated that the colorectal cancer screening tests most often recommended to asymptomatic, average-risk patients were FOBT and flexible sigmoidoscopy, and that colonoscopy and barium enema were infrequently recom-
American Journal of Preventive Medicine, Volume 21, Number 2
mended (Carrie Klabunde, National Cancer Institute, personal/written communication, 2001). The strong associations we found between colorectal cancer screening tests and other medical screening tests suggest that there may be important opportunities to increase screening rates by educating healthcare providers and encouraging them to offer colorectal cancer screening to their patients. The low rates of colorectal cancer screening in all subgroups in this analysis indicate the need to increase awareness of the importance of screening in all segments of the U.S. population. Recent activities designed to do this include the designation by the U.S. Congress of March 2000 as the first Colorectal Cancer Awareness Month and the development by three federal partners—Centers for Disease Control and Prevention, Health Care Financing Administration, and National Cancer Institute— of an educational intervention for healthcare providers and a media campaign for the public about colorectal cancer screening. These activities and others are needed to substantially increase the rates of screening for colorectal cancer and reduce mortality from this important disease. Data from this paper were presented at the American Public Health Association conference on 10 November 1999.
References 1. Greenlee RT, Hill-Harmon MB, Murray T, Thun M. Cancer statistics, 2001. CA Cancer J Clin 2001;51:15–36. 2. Mandel JS, Bond JH, Church TR, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. N Engl J Med 1993;328:1365–71. 3. Kronborg O, Fenger C, Olsen J, Jorgensen OD, Sondergaard O. Randomised study of screening for colorectal cancer with faecal-occult-blood test. Lancet 1996;348:1467–71. 4. Hardcastle JD, Chamberlain JO, Robinson MHE, et al. Randomised controlled trial of faecal-occult-blood screening for colorectal cancer. Lancet 1996;348:1472–7. 5. Selby JV, Friedman GD, Quesenberry CP, Weiss NS. A case-control study of screening sigmoidoscopy and mortality from colorectal cancer. N Engl J Med 1992;326:653–7. 6. Newcomb PA, Norfleet RG, Storer BE, Surawicz TS, Marcus PM. Screening sigmoidoscopy and colorectal cancer mortality. J Natl Cancer Inst 1992;84: 1572–5. 7. Muller AD, Sonnenberg A. Protection by endoscopy against death from colorectal cancer. Arch Intern Med 1995;155:1741– 8.
8. Smith RA, von Eschenbach AC, Wender R, et al. American Cancer Society (ACS) guidelines for the early detection of cancer: update of early detection guidelines for prostate, colorectal, and endometrial cancers. CA Cancer J Clin 2001;51:38 –75. 9. U.S. Preventive Services Task Force. Guide to clinical preventive services, 2nd ed. Alexandria, VA: International Medical Publishing, 1996. 10. Frankel LR. The report of the CASRO Task Force on response rates. In: Wiseman F, ed. Improving data quality in a sample survey. Cambridge, MA: Marketing Science Institute, 1983:1–11. 11. Winawer SJ, Fletcher RH, Miller L, et al. Colorectal cancer screening: clinical guidelines and rationale. Gastroenterology 1997;112:594 – 642. 12. Ransohoff DF, Lang CA. Screening for colorectal cancer with the fecal occult blood test: a background paper. Ann Intern Med 1997;126:811–22. 13. SAS statistical analysis software. Cary, NC: SAS Institute, 1996. 14. SUDAAN Software for the Statistical Analysis of Correlated Data. Research Triangle Park, NC: Research Triangle Institute, 1997. 15. Centers for Disease Control and Prevention. Screening for colorectal cancer—United States, 1997. MMWR Morb Mort Wkly Rep 1999;48:116 – 21. 16. Eddy D. ACS report on the cancer-related health checkup. CA Cancer J Clin 1980;30:193–240. 17. Brown ML, Potosky AL, Thompson GB, Kessler LG. The knowledge and use of screening tests for colorectal and prostate cancer: data from the 1987 National Health Interview Survey. Prev Med 1990;19:562–74. 18. Centers for Disease Control and Prevention. Trends in cancer screening— United States, 1987 and 1992. MMWR Morb Mort Wkly Rep 1995;45:57– 61. 19. Hoffman-Goetz L, Breen NL, Meissner H. The impact of social class on the use of cancer screening within three racial/ethnic groups in the United States. Ethn Dis 1998;8:43–51. 20. Mandelson MT, LaCroix AZ, Anderson LA, Nadel MR, Lee NC. Comparison of self-reported fecal occult blood testing with automated laboratory records among older women in a health maintenance organization. Am J Epidemiol 1999;150:617–21. 21. Mayer-Oakes SA, Atchison KA, Matthias RE, DeJong FJ, Lubben J, Schweitzer SO. Mammography use in older women with regular physicians: what are the predictors? Am J Prev Med 1996;12:44 –50. 22. Rakowski W, Rimer BK, Bryant SA. Integrating behavior and intention regarding mammography by respondents in the 1990 National Health Interview Survey of Health Promotion and Disease Prevention. Public Health Rep 1993;108:605–24. 23. Sutton S, Bickler G, Sancho-Aldridge J, Saidi G. Prospective study of predictors of attendance for breast screening in inner London. J Epidemiol Community Health 1994;48:65–73. 24. U.S. Bureau of the Census. Phoneless in America. Washington, DC: U.S. Department of Commerce, Economics and Statistics Administration, Bureau of the Census, 1994 (Statistical brief 94-16). 25. Gordon NP, Hiatt RA, Lampert DI. Concordance of self-reported data and medical record audit for six cancer screening procedures. J Natl Cancer Inst 1993;85:566 –70. 26. Brown JB, Adams ME. Patients as reliable reporters of medical care process: recall of ambulatory encounter events. Med Care 1992;30;400 –11. 27. Montano DE, Phillips WR. Cancer screening by primary care physicians: a comparison of rates obtained from physician self-report, patient survey, and chart audit. Am J Public Health 1995;85:795– 800. 28. Baier M, Calonge N, Cutter G, et al. Validity of self-reported colorectal cancer screening behavior. Cancer Epi Bio Prev 2000;9:229 –32.
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A total of 52,754 respondents aged ⱖ50 years were questioned in the 1997 Behavioral Risk Factor Surveillance System (BRFSS) survey (a random-digit-dialing telephone survey of the non-institutionalized U.S. population) about their use of FOBT and sigmoidoscopy.
Results:
The age-adjusted proportion of respondents who reported having had a colorectal cancer screening test during the recommended time interval (past year for FOBT and past 5 years for sigmoidoscopy) was 19.8% for FOBT, 30.5% for sigmoidoscopy, and 41.1% for either FOBT or sigmoidoscopy. Rates of use of colorectal cancer screening tests were higher for those who had other screening tests (mammography, Papanicolaou smear, and cholesterol check). There were also differences in rates of use of colorectal cancer screening tests according to other health behaviors (smoking, seat belt use, fruit and vegetable intake, and physical activity) and several demographic factors. However, none of the subgroups that we examined reported a rate of FOBT use above 29% within the past year or a rate of sigmoidoscopy use above 41% within the past 5 years.
Conclusions: While rates of use of FOBT and sigmoidoscopy were higher among people who practiced other healthy behaviors, rates of use were still quite low in all subgroups. There is a need for increased awareness of the importance of colorectal cancer screening. Medical Subject Headings (MeSH): colorectal neoplasms, mass screening, occult blood, sigmoidoscopy (Am J Prev Med 2001;21(2):132–137) © 2001 American Journal of Preventive Medicine
Introduction
C
olorectal cancer is the second leading cause of cancer death in the United States, following lung cancer.1 According to the American Cancer Society (ACS), there will be approximately 135,400 new cases of colorectal cancer in 2001 and approximately 56,700 deaths due to the disease.1 There is now strong evidence that screening can reduce colorectal cancer mortality. Several randomized controlled trials have shown that the fecal occult blood test (FOBT) can reduce colorectal cancer mortality.2– 4 Several case– control studies found that sigmoidoscopy was associated with reduced risk of colorectal cancer mortality.5–7 Based on this evidence, there is now consensus among medical organizations that screening
From the Division of Cancer Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia Address correspondence and reprint requests to: Jean A. Shapiro, PhD, Centers for Disease Control and Prevention, NCCDPHP, DCPC, Mailstop K-55, 4770 Buford Hwy NE, Atlanta, GA 30341-3717.
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is effective in reducing colorectal cancer mortality. Screening is recommended by several major organizations, including the U.S. Preventive Services Task Force (USPSTF) and the ACS.8,9 We analyzed data from the 1997 Behavioral Risk Factor Surveillance System (BRFSS) to determine the rates of use of FOBT and sigmoidoscopy, and to determine if these rates differ by demographic factors and other health behaviors.
Methods The BRFSS is a state-based, random-digit-dialing telephone survey of the non-institutionalized U.S. population aged ⱖ18 years. In 1997, all 50 states, the District of Columbia, and Puerto Rico participated in the BRFSS. The median state response rate for the entire survey was 76.5%, calculated as the percentage of eligible respondents successfully contacted who completed the telephone interview. A response rate was also calculated according to a formula developed by the Council of American Survey Research Organizations, which assigns phone numbers with unknown eligibility status as eligible in the same proportion as among all phone numbers
Am J Prev Med 2001;21(2) 0749-3797/01/$–see front matter © 2001 American Journal of Preventive Medicine • Published by Elsevier Science Inc. PII S0749-3797(01)00329-4
of known status.10 The median state response rate according to this formula was 62.1%. Survey respondents aged ⱖ40 years were asked about both the blood stool test and sigmoidoscopy/proctoscopy. While these tests can be used for both screening and diagnosis, the survey questions were not asked in a manner that allowed the respondents to identify the indication for the test. We use the term “colorectal cancer screening tests” here to refer to these tests regardless of their indication, as these tests are often used for screening. For the blood stool test or FOBT, the respondents were told: “A blood stool test is a test that may use a special kit at home to determine whether the stool contains blood.” They were then asked if they had ever had this test using a home kit and, if so, when they had their last blood stool test using a home kit. In 1997 for the first time, the BRFSS questions about FOBT specified that the test used a home kit. Previous BRFSS survey questions did not address whether stool samples were obtained at home using a kit or as part of a digital rectal examination. The recommended method of obtaining a stool sample for an FOBT is through use of the home kit.8,11,12 Use of the home kit allows for collection of multiple samples and should be performed in conjunction with dietary restrictions to decrease the possibility of false-positive or false-negative results from certain foods and medications.11,12 For sigmoidoscopy/proctoscopy, respondents were told: “A sigmoidoscopy or proctoscopy is when a tube is inserted in the rectum to view the bowel for signs of cancer and other health problems.” They were then asked if they had ever had this examination and, if so, when they had their last sigmoidoscopy or proctoscopy. While the use of the term “proctoscopy” is inconsistent in the literature, the term is usually used to refer to the rigid sigmoidoscopy, a test that uses a rigid instrument shorter than the instrument used for flexible sigmoidoscopy. For colorectal cancer screening, flexible sigmoidoscopy is currently recommended rather than rigid sigmoidoscopy. For the purpose of this discussion, sigmoidoscopy/proctoscopy will hereafter be referred to as sigmoidoscopy. For our analysis, we included only respondents aged ⱖ50 years, because it is recommended that colorectal cancer screening be initiated at age 50 for average-risk people who do not have a family history of the disease or certain other risk factors.8,9,11 All of our analyses refer to tests within the most commonly recommended time intervals: during the past year for FOBT and during the past 5 years for sigmoidoscopy. All respondents were also asked questions about demographics, race, healthcare coverage, cholesterol screening, seatbelt use, and cigarette smoking. Women were asked about use of mammography and Papanicolaou (Pap) smears. Respondents in 11 states were asked about fruit and vegetable consumption, and respondents in 12 states were asked about physical activity. A total of 52,754 respondents aged ⱖ50 years were questioned about use of FOBT and sigmoidoscopy. Respondents who refused to answer a question or who did not know the answer to a question were excluded from analyses of that specific question. The total number of respondent refusals or unknowns was 1328 (2.5%) for the FOBT questions and 1658 (3.1%) for the sigmoidoscopy questions. For the other variables in Tables 1 and 2, the total number of respondent refusals or unknowns was ⬍4% for all variables except income
(20%) and fruit and vegetable servings (10%). To minimize the amount of missing data in analyses of each specific variable, we excluded only respondents who were missing data on the specific variables included in each analysis and did not exclude respondents who were missing data for other variables. The data were weighted to the respondent’s probability of selection and to the race-, age-, and gender-specific population from the most current census data for each state. Proportions and standard errors were calculated using SAS13 and SUDAAN,14 a statistical package for analyzing complex survey data. All proportions were adjusted for age in 5-year groups, using the BRFSS population as the standard population. Logistic regression in SUDAAN was used to calculate odds ratios (ORs) and 95% confidence intervals. All OR estimates are presented adjusted for age, gender (except for mammography and Pap smear use), education, and healthcare coverage using the categories presented in Table 1.
Results The age-adjusted proportion of respondents who reported having a colorectal cancer screening test during the recommended time interval was 19.8% for FOBT, 30.5% for sigmoidoscopy, and 41.1% for either FOBT or sigmoidoscopy (Table 1). A total of 9.5% reported having both tests during the recommended time intervals. Rates of use of colorectal cancer screening tests by demographic factors have been reported previously unadjusted for age15 and are presented age adjusted in Table 1. The rates of FOBT use were ⬍25% in all of the demographic subgroups that we examined, ranging from 9.5% for people without healthcare coverage to 24.0% for people with incomes of ⱖ$50,000. For sigmoidoscopy, rates were ⬍41% in all of the demographic subgroups we examined, ranging from 18.8% for people without healthcare coverage to 40.6% for people with incomes of ⱖ$50,000. Women were slightly more likely than men to report having an FOBT, but men were slightly more likely to report having a sigmoidoscopy. Asian/Pacific Islanders and American Indians/Alaska Natives were less likely to report having a colorectal cancer–screening test than blacks or whites. However, the sample size for racial groups other than blacks and whites was fairly small. People of Spanish or Hispanic origin were less likely to report having a colorectal cancer–screening test. Reported use of colorectal cancer–screening tests increased with increasing educational level and income. People without healthcare coverage were less likely than those with healthcare coverage to report having colorectal cancer– screening tests. Reported use of colorectal cancer– screening tests increased with each decade of age from ages 50 to 59 through ages 70 to 79, and then decreased for the group aged ⱖ80. Table 2 presents age-adjusted rates of use of colorectal cancer–screening tests by other health behaviors. The largest differences in rates of use of colorectal Am J Prev Med 2001;21(2)
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Table 1. FOBT and sigmoidoscopy by demographic factors, Behavioral Risk Factor Surveillance System (BRFSS), 1997
FOBT within past year Characteristic Total (50,490b) Gender Male Female Race White Black Asian/Pacific Islander American Indian/Alaska Native Other Spanish or Hispanic origin No Yes Age (years) 50–59 60–69 70–79 ⱖ80 Education ⬍12 years High school graduate Some college/technical school College graduate Income (annual household) ⬍$20,000 $20,000–35,000 $35,000–50,000 ⱖ$50,000 Healthcare coverage No Yes
b
Sigmoidoscopy within past 5 years
Either test within recommended time intervala
%c
(95% CI)
%c
(95% CI)
%c
(95% CI)
19.8
(19.3–20.3)
30.5
(29.9–31.1)
41.1
(40.4–41.8)
19583 30907
18.8 20.8
(17.9–19.6) (20.1–21.5)
35.7 26.5
(34.7–36.8) (25.8–27.2)
44.5 38.6
(43.4–45.5) (37.7–39.4)
44736 3511 723 520 784
20.1 20.4 12.3 14.2 14.0
(19.5–20.7) (18.4–22.4) (8.4–16.2) (9.3–19.0) (10.4–17.7)
31.0 29.9 26.7 26.3 19.7
(30.3–31.6) (27.7–32.2) (20.5–32.8) (19.6–33.0) (15.5–24.0)
41.6 40.7 35.1 34.7 27.7
(40.9–42.3) (38.3–43.1) (28.3–42.0) (27.8–41.7) (22.8–32.5)
47855 2416
20.3 13.7
(19.7–20.8) (11.6–15.7)
30.8 26.6
(30.2–31.4) (23.6–29.6)
41.6 33.7
(40.9–42.3) (30.6–36.9)
18333 14835 12247 5075
15.5 21.8 23.7 20.1
(14.6–16.3) (20.8–22.8) (22.5–24.8) (18.4–21.8)
23.6 33.2 37.0 31.6
(22.6–24.6) (32.0–34.4) (35.7–38.3) (29.7–33.6)
33.1 44.0 48.8 42.0
(32.1–34.2) (42.8–45.2) (47.5–50.2) (39.9–44.0)
10300 17636 11677 10744
15.4 19.2 21.1 23.8
(14.3–16.5) (18.3–20.1) (19.9–22.2) (22.6–25.1)
26.2 28.0 31.9 37.9
(24.8–27.6) (27.0–29.0) (30.6–33.2) (36.5–39.4)
35.1 38.6 43.6 48.6
(33.6–36.6) (37.5–39.7) (42.2–44.9) (47.1–50.1)
13448 12678 6487 8356
15.6 19.7 22.0 24.0
(14.7–16.5) (18.6–20.7) (20.3–23.7) (22.1–25.8)
25.3 30.1 33.6 40.6
(24.1–26.5) (28.9–31.3) (31.6–35.5) (38.5–42.7)
34.2 40.7 44.5 50.9
(32.9–35.5) (39.4–42.0) (42.6–46.5) (48.8–53.1)
3248 47191
9.5 20.5
(7.4–11.6) (20.0–21.1)
18.8 31.3
(15.6–22.0) (30.7–31.9)
24.2 42.2
(20.7–27.6) (41.5–42.9)
n
a
Respondents who had either an FOBT within the past year or a sigmoidoscopy within the past 5 years. Number who answered both the FOBT and sigmoidoscopy questions. Number who answered either the FOBT questions or the sigmoidoscopy questions may be slightly higher. For some variables, the numbers do not add up to the total because of missing data. c All percentages are adjusted for age. CI, confidence interval; FOBT, fecal occult blood test b
cancer–screening tests were between those who reported using other screening tests (e.g., mammogram, Pap smear, and cholesterol check) and those who did not. Women who reported having a mammogram or Pap smear within the past year and people who reported having a cholesterol check within the past 2 years were much more likely to report having an FOBT or sigmoidoscopy. People who had not had their cholesterol checked in the past 2 years had the lowest screening rates of all the subgroups we examined (6.4% for FOBT and 15.3% for sigmoidoscopy). There were also differences in rates according to other health behaviors. Current smokers were less likely than either former or never smokers to report use of FOBT or sigmoidoscopy. People who used seat belts were more likely to report use of these tests, as were people who ate more fruits and vegetables or who were physically active. Table 3 presents ORs for the association of selected 134
health behaviors with FOBT and sigmoidoscopy, adjusted for age, gender, education, and healthcare coverage. The relationships seen in Table 2 persisted after adjustment for these factors. Use of mammography, Pap smears, and cholesterol checks was strongly associated with use of FOBT and of sigmoidoscopy. Seat belt use, greater fruit and vegetable intake, and physical activity were also associated with use of colorectal cancer–screening tests. Current smoking was inversely associated with use of colorectal cancer–screening tests.
Discussion Our results from the 1997 BRFSS, a survey that included more than 50,000 respondents aged ⱖ50 years in all U.S. states, indicate that self-reported rates of use of colorectal cancer–screening tests are uniformly low. The USPSTF, ACS, and other organizations recommend the use of FOBT and/or flexible sigmoidoscopy
American Journal of Preventive Medicine, Volume 21, Number 2
Table 2. FOBT and sigmoidoscopy by other health behaviors, Behavioral Risk Factor Surveillance System (BRFSS), 1997 Sigmoidoscopy within past 5 years
FOBT within past year Characteristic Mammogram within past year No Yes Pap smear within past year No Yes Cholesterol check within past 2 years No Yes Cigarette smoking status Never Former Current Seatbelt use Never or seldom Sometimes Always or nearly always Daily fruit and vegetable servingsc ⬍2 2–4 5⫹ Physical activityd None Irregular Regular
na
%b
(95% CI)
%b
(95% CI)
12942 17716
10.0 28.3
(9.2–10.8) (27.3–29.3)
16.7 33.4
(15.7–17.7) (32.4–34.5)
13849 16441
11.8 28.7
(11.0–12.6) (27.6–29.7)
19.8 32.6
(18.8–20.8) (31.5–33.7)
10297 38496
6.4 23.4
(5.7–7.2) (22.8–24.0)
15.3 34.6
(14.2–16.5) (33.9–35.3)
24345 17405 8592
20.4 21.3 14.1
(19.7–21.2) (20.4–22.2) (12.8–15.4)
29.4 34.3 25.2
(28.5–30.3) (33.2–35.3) (23.5–26.8)
3379 3216 43492
11.8 13.8 20.8
(10.1–13.4) (11.9–15.8) (20.2–21.3)
24.2 24.6 31.4
(21.9–26.5) (22.3–26.9) (30.8–32.1)
610 5304 2754
13.5 18.0 25.5
(9.5–17.4) (16.5–19.5) (23.1–27.9)
26.8 29.4 33.4
(21.3–32.4) (27.7–31.1) (30.9–35.9)
4274 2578 4180
16.7 19.5 24.4
(15.0–18.3) (17.2–21.9) (22.3–26.4)
25.2 26.8 35.6
(23.4–27.0) (24.3–29.4) (33.3–37.8)
a
Number who answered both the FOBT and sigmoidoscopy questions. Number who answered either the FOBT questions or the sigmoidoscopy questions may be slightly higher. b All percentages are adjusted for age. c Only 11 states asked the questions about fruits and vegetables. d Physical activity in leisure time. Only 12 states asked the questions about physical activity. Regular physical activity was defined as any physical activity reported at least three times per week for at least 20 minutes each time. CI, confidence interval; FOBT, fecal occult blood test
for screening average-risk people aged ⱖ50 years,8,9,11 but we found that only about 20% of respondents reported an FOBT within the past year and only about 30% reported a sigmoidoscopy within the past 5 years. No subgroup that we examined reported a rate of FOBT use within the past year above 29% or a rate of sigmoidoscopy use within the past 5 years above 41%. Medical organizations differ on whether they recommend use of FOBT or flexible sigmoidoscopy alone or that both tests be performed.8,9,11 We found that about 41% of respondents reported having either FOBT within the past year or sigmoidoscopy within the past 5 years, while only about 10% reported having both tests within these recommended time intervals. The reported rates of colorectal cancer screening are much lower than for other widely recommended cancer screening tests. For example, data from the 1997 BRFSS indicate that only about 39% of women aged ⱖ50 years reported having either FOBT or sigmoidoscopy within the recommended time interval, while about 60% of these women reported having a mammogram within the past year and about 56% reported having a Pap smear within the past year. Rates of colorectal cancer screening may be lower because
widespread consensus about the value of screening has been reached only recently. Although ACS has recommended both FOBT and sigmoidoscopy since 1980,16 the USPSTF did not recommend these screening tests until 1996.9 The evidence for the benefit of colorectal cancer screening was strengthened with the publication of findings from several well-designed studies—two case– control studies of sigmoidoscopy in 19925,6 and the first randomized controlled trial of FOBT in 19932—suggesting that screening reduced colorectal cancer mortality. We found that use of sigmoidoscopy and FOBT increased with increasing educational level and income and that Hispanics were less likely to use these tests. These results are similar to results from the 1987 and 1992 National Health Interview Surveys (NHIS), inperson household interviews of the U.S. civilian, noninstitutionalized population.17–19 Results for age and for race have been inconsistent.17–19 There is very little data on the association between colorectal cancer screening tests and other health behaviors. The 1987 NHIS found that there was no association between current smoking and FOBT or proctoscopy.17 A 1995 survey of women enrolled in Am J Prev Med 2001;21(2)
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Table 3. Association of selected health behaviors with FOBT and sigmoidoscopy, Behavioral Risk Factor Surveillance System (BRFSS), 1997 FOBT within past year Characteristic
ORa (95% CI)
Mammogram within past year No 1.0 (reference) Yes 3.4 (3.1–3.8) Pap smear within past year No 1.0 (reference) Yes 2.9 (2.7–3.2) Cholesterol check within past 2 years No 1.0 (reference) Yes 4.3 (3.8–4.9) Cigarette smoking status Never 1.0 (reference) Former 1.1 (1.0–1.2) Current 0.7 (0.6–0.8) Seat-belt use Never or seldom 1.0 (reference) Sometimes 1.2 (1.0–1.6) Always or nearly 1.8 (1.5–2.2) always Daily fruit and vegetable servingsb ⬍2 1.0 (reference) 2–4 1.3 (0.9–1.9) 5⫹ 2.0 (1.4–2.9) Physical activityc None 1.0 (reference) Irregular 1.2 (1.0–1.4) Regular 1.5 (1.3–1.8)
Sigmoidoscopy within past 5 years ORa (95% CI) 1.0 (reference) 2.4 (2.2–2.7) 1.0 (reference) 1.9 (1.7–2.1) 1.0 (reference) 2.8 (2.6–3.1) 1.0 (reference) 1.1 (1.1–1.2) 0.8 (0.7–0.9) 1.0 (reference) 1.1 (0.9–1.3) 1.5 (1.3–1.7) 1.0 (reference) 1.1 (0.8–1.5) 1.3 (1.0–1.8) 1.0 (reference) 1.0 (0.9–1.2) 1.5 (1.3–1.7)
a
All odds ratios are adjusted for age, gender (except for mammography and Pap smear use), education, and health care coverage. Only 11 states asked the questions about fruits and vegetables. c Physical activity in leisure time. Only 12 states asked the questions about physical activity. Regular physical activity was defined as any physical activity reported at least three times per week for at least 20 minutes each time. CI, confidence interval; FOBT, fecal occult blood test; OR, odds ratio b
Group Health Cooperative, a health maintenance organization in Washington state, found that current smokers were less likely than former or never smokers to report an FOBT within the past 5 years.20 In the Group Health Cooperative survey, women who reported a recent mammogram also were more likely to report an FOBT within the past 5 years.20 In our analysis of the 1997 BRFSS, people who practiced other healthy behaviors were more likely to have had colorectal cancer screening tests. In particular, use of other screening tests (mammography within the past year, Pap smear within the past year, and cholesterol check within the past 2 years) was strongly associated with use of colorectal cancer screening tests within the recommended time intervals (past year for FOBT and past 5 years for sigmoidoscopy). Possible reasons for the strong associations of colorectal cancer screening tests with these other screening tests include interest of the patient or the healthcare provider in screening and the 136
fact that these tests usually involve a visit to a healthcare provider. A visit to the healthcare provider for one screening test may provide an opportunity for the provider to recommend or perform another screening test. However, rates of use of colorectal cancer screening tests in our study were still quite low, even among people who had recently undergone other screening tests. Our finding of an association between use of colorectal cancer screening tests and other health behaviors is consistent with results from studies of other cancer screening tests. For example, use of mammography has been associated with health behaviors such as engaging in regular exercise, being a nonsmoker, having Pap smear screening, using seat belts, and having dental checkups.21–23 There are several limitations to this analysis. Because the BRFSS is a telephone survey, the results may not be generalizable to people without telephones. However, the vast majority (approximately 95%) of U.S. households have telephones.24 Another limitation is that 23.5% of the eligible respondents who were successfully contacted did not complete the telephone interview. Results for colorectal cancer screening rates may be biased if the respondents’ rates of use of colorectal cancer screening tests were substantially different from the nonrespondents’ rates. In addition, we were unable to distinguish between tests done for screening and tests done for diagnosis. If some of these tests were done for diagnostic purposes, the rate of use of these tests for screening would be lower than reported here. Some respondents may also have incorrectly reported their use of colorectal cancer screening tests or other information in the survey. In particular, information about colonoscopies or barium enemas may have been included in responses to the question about sigmoidoscopy. However, studies that compared self-report of colorectal cancer screening to information from medical records have generally found moderate to good agreement between the two data sources.20,25–28 The 1997 BRFSS did not explicitly ask about use of colonoscopy or barium enema, which may be used for colorectal cancer screening. However, these procedures were probably infrequently used for screening in 1997. Before 1997, no major guidelines recommended colonoscopy or barium enema for screening of people not at high risk for colorectal cancer. The USPSTF did not recommend any colorectal cancer screening tests until 1996, when it published guidelines recommending FOBT and/or sigmoidoscopy, but concluded that there was insufficient evidence to recommend barium enema or colonoscopy.9 Data from a 1999 –2000 national survey of primary care physicians indicated that the colorectal cancer screening tests most often recommended to asymptomatic, average-risk patients were FOBT and flexible sigmoidoscopy, and that colonoscopy and barium enema were infrequently recom-
American Journal of Preventive Medicine, Volume 21, Number 2
mended (Carrie Klabunde, National Cancer Institute, personal/written communication, 2001). The strong associations we found between colorectal cancer screening tests and other medical screening tests suggest that there may be important opportunities to increase screening rates by educating healthcare providers and encouraging them to offer colorectal cancer screening to their patients. The low rates of colorectal cancer screening in all subgroups in this analysis indicate the need to increase awareness of the importance of screening in all segments of the U.S. population. Recent activities designed to do this include the designation by the U.S. Congress of March 2000 as the first Colorectal Cancer Awareness Month and the development by three federal partners—Centers for Disease Control and Prevention, Health Care Financing Administration, and National Cancer Institute— of an educational intervention for healthcare providers and a media campaign for the public about colorectal cancer screening. These activities and others are needed to substantially increase the rates of screening for colorectal cancer and reduce mortality from this important disease. Data from this paper were presented at the American Public Health Association conference on 10 November 1999.
References 1. Greenlee RT, Hill-Harmon MB, Murray T, Thun M. Cancer statistics, 2001. CA Cancer J Clin 2001;51:15–36. 2. Mandel JS, Bond JH, Church TR, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. N Engl J Med 1993;328:1365–71. 3. Kronborg O, Fenger C, Olsen J, Jorgensen OD, Sondergaard O. Randomised study of screening for colorectal cancer with faecal-occult-blood test. Lancet 1996;348:1467–71. 4. Hardcastle JD, Chamberlain JO, Robinson MHE, et al. Randomised controlled trial of faecal-occult-blood screening for colorectal cancer. Lancet 1996;348:1472–7. 5. Selby JV, Friedman GD, Quesenberry CP, Weiss NS. A case-control study of screening sigmoidoscopy and mortality from colorectal cancer. N Engl J Med 1992;326:653–7. 6. Newcomb PA, Norfleet RG, Storer BE, Surawicz TS, Marcus PM. Screening sigmoidoscopy and colorectal cancer mortality. J Natl Cancer Inst 1992;84: 1572–5. 7. Muller AD, Sonnenberg A. Protection by endoscopy against death from colorectal cancer. Arch Intern Med 1995;155:1741– 8.
8. Smith RA, von Eschenbach AC, Wender R, et al. American Cancer Society (ACS) guidelines for the early detection of cancer: update of early detection guidelines for prostate, colorectal, and endometrial cancers. CA Cancer J Clin 2001;51:38 –75. 9. U.S. Preventive Services Task Force. Guide to clinical preventive services, 2nd ed. Alexandria, VA: International Medical Publishing, 1996. 10. Frankel LR. The report of the CASRO Task Force on response rates. In: Wiseman F, ed. Improving data quality in a sample survey. Cambridge, MA: Marketing Science Institute, 1983:1–11. 11. Winawer SJ, Fletcher RH, Miller L, et al. Colorectal cancer screening: clinical guidelines and rationale. Gastroenterology 1997;112:594 – 642. 12. Ransohoff DF, Lang CA. Screening for colorectal cancer with the fecal occult blood test: a background paper. Ann Intern Med 1997;126:811–22. 13. SAS statistical analysis software. Cary, NC: SAS Institute, 1996. 14. SUDAAN Software for the Statistical Analysis of Correlated Data. Research Triangle Park, NC: Research Triangle Institute, 1997. 15. Centers for Disease Control and Prevention. Screening for colorectal cancer—United States, 1997. MMWR Morb Mort Wkly Rep 1999;48:116 – 21. 16. Eddy D. ACS report on the cancer-related health checkup. CA Cancer J Clin 1980;30:193–240. 17. Brown ML, Potosky AL, Thompson GB, Kessler LG. The knowledge and use of screening tests for colorectal and prostate cancer: data from the 1987 National Health Interview Survey. Prev Med 1990;19:562–74. 18. Centers for Disease Control and Prevention. Trends in cancer screening— United States, 1987 and 1992. MMWR Morb Mort Wkly Rep 1995;45:57– 61. 19. Hoffman-Goetz L, Breen NL, Meissner H. The impact of social class on the use of cancer screening within three racial/ethnic groups in the United States. Ethn Dis 1998;8:43–51. 20. Mandelson MT, LaCroix AZ, Anderson LA, Nadel MR, Lee NC. Comparison of self-reported fecal occult blood testing with automated laboratory records among older women in a health maintenance organization. Am J Epidemiol 1999;150:617–21. 21. Mayer-Oakes SA, Atchison KA, Matthias RE, DeJong FJ, Lubben J, Schweitzer SO. Mammography use in older women with regular physicians: what are the predictors? Am J Prev Med 1996;12:44 –50. 22. Rakowski W, Rimer BK, Bryant SA. Integrating behavior and intention regarding mammography by respondents in the 1990 National Health Interview Survey of Health Promotion and Disease Prevention. Public Health Rep 1993;108:605–24. 23. Sutton S, Bickler G, Sancho-Aldridge J, Saidi G. Prospective study of predictors of attendance for breast screening in inner London. J Epidemiol Community Health 1994;48:65–73. 24. U.S. Bureau of the Census. Phoneless in America. Washington, DC: U.S. Department of Commerce, Economics and Statistics Administration, Bureau of the Census, 1994 (Statistical brief 94-16). 25. Gordon NP, Hiatt RA, Lampert DI. Concordance of self-reported data and medical record audit for six cancer screening procedures. J Natl Cancer Inst 1993;85:566 –70. 26. Brown JB, Adams ME. Patients as reliable reporters of medical care process: recall of ambulatory encounter events. Med Care 1992;30;400 –11. 27. Montano DE, Phillips WR. Cancer screening by primary care physicians: a comparison of rates obtained from physician self-report, patient survey, and chart audit. Am J Public Health 1995;85:795– 800. 28. Baier M, Calonge N, Cutter G, et al. Validity of self-reported colorectal cancer screening behavior. Cancer Epi Bio Prev 2000;9:229 –32.
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