Volume 100, Issue 10 p. 2093-2103
Original Article
Free Access

Patterns and predictors of colorectal cancer test use in the adult U.S. population

Laura C. Seeff M.D.

Corresponding Author

Laura C. Seeff M.D.

Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia

Fax: (770) 488-4639

Centers for Disease Control and Prevention, DCPC, 4770 Buford Highway, NE, Mailstop K-55, Atlanta, GA 30341-3717===Search for more papers by this author
Marion R. Nadel Ph.D., M.P.H.

Marion R. Nadel Ph.D., M.P.H.

Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia

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Carrie N. Klabunde Ph.D.

Carrie N. Klabunde Ph.D.

Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, Maryland

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Trevor Thompson B.S.

Trevor Thompson B.S.

Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia

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Jean A. Shapiro Ph.D.

Jean A. Shapiro Ph.D.

Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia

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Sally W. Vernon Ph.D.

Sally W. Vernon Ph.D.

University of Texas-Houston School of Public Health, Center for Health Promotion and Prevention Research, Houston, Texas

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Ralph J. Coates Ph.D.

Ralph J. Coates Ph.D.

Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia

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First published: 20 April 2004
Citations: 387

Abstract

BACKGROUND

Screening is effective in reducing the incidence and mortality of colorectal cancer. Rates of colorectal cancer test use continue to be low.

METHODS

The authors analyzed data from the National Health Interview Survey concerning the use of the home-administered fecal occult blood test (FOBT) and sigmoidoscopy/colonoscopy/proctoscopy to estimate current rates of colorectal cancer test use and to identify factors associated with the use or nonuse of tests.

RESULTS

In 2000, 17.1% of respondents reported undergoing a home FOBT within the past year, 33.9% reported undergoing an endoscopy within the previous 10 years, and 42.5% reported undergoing either test within the recommended time intervals. The use of colorectal cancer tests varied by gender, race, ethnicity, age, education, income, health care coverage, and having a usual source of care. Having seen a physician within the past year had the strongest association with test use. Lack of awareness and lack of physician recommendation were the most commonly reported barriers to undergoing such tests.

CONCLUSIONS

Less than half of the U.S. population age ≥ 50 years underwent colorectal cancer tests within the recommended time intervals. Educational initiatives for patients and providers regarding the importance of colorectal cancer screening, efforts to reduce disparities in test use, and ensuring that all persons have access to routine primary care may help increase screening rates. Cancer 2004. © 2004 American Cancer Society.

In accordance with evidence that screening reduces colorectal cancer (CRC) incidence and mortality,1-7 several sets of national guidelines now recommend regular CRC screening for average-risk persons age ≥ 50 years using 1 or more of the following options: annual home fecal occult blood test (FOBT), flexible sigmoidoscopy every 5 years, a combination of home FOBT and flexible sigmoidoscopy, colonoscopy every 10 years, and/or double-contrast barium enema every 5 years.8-10 However, the adoption of these guidelines is occurring slowly and test use remains low.

We analyzed data from the 2000 Cancer Control Supplement of the National Health Interview Survey (NHIS) regarding the use of the home-administered FOBT and sigmoidoscopy/colonoscopy/proctoscopy to estimate the most current rates of CRC test use, to evaluate factors previously described in association with CRC test use, and to describe first-time national estimates of barriers to CRC testing from the perspective of the general public.

MATERIALS AND METHODS

The NHIS, conducted by the National Center for Health Statistics (NCHS), the Centers for Disease Control and Prevention (CDC), is an in-person survey that collects health behavior and sociodemographic information from the civilian, noninstitutionalized U.S. population. The current survey oversamples black and Hispanic populations. The 2000 NHIS included a Cancer Control Module.11

Response Rates

In 2000, the household response rate was 88.9% for the core NHIS survey and 72.1% for the Cancer Control Module. Survey responses were weighted to reflect nonresponse and the probability of selection. A small percentage (3.6%) of persons did not provide valid responses to at least 50% of the Cancer Control Module questions and were excluded from analysis.11

The 2000 Cancer Control Module

The 2000 NHIS Cancer Control Module included questions concerning diet and nutrition; physical activity; tobacco; screening for breast, cervical, skin, prostate, and colorectal cancer; genetic testing; and family history of cancer. Information regarding cigarette smoking, alcohol intake, and leisure time activity was collected in the core questionnaire. Questions regarding three types of endoscopic tests (proctoscopy, sigmoidoscopy, and colonoscopy) were asked separately for the first time in the 2000 NHIS.

CRC Screening Questions

In the 2000 NHIS, 11,734 men and women age ≥ 50 years responded to questions regarding the use of FOBT, and 11,816 responded to questions regarding the use of sigmoidoscopy, colonoscopy, or proctoscopy. Respondents were asked whether they had ever undergone an FOBT, the timing of their most recent test, and the reason the test was performed. A definition of FOBT was provided if requested. Response categories for reasons for receiving the examination included (verbatim): 1) part of a routine physical examination/screening test; 2) because of a specific problem; 3) follow-up test of an earlier test or screening examination; 4) family history; and 5) other. Respondents were asked to identify only the main reason for receiving a test and multiple reasons were not accepted. Categories 1 and 4 were combined into screening categories and Categories 2, 3, and 5 were combined into nonscreening categories. Respondents who had never had undergone a FOBT or had not undergone one recently (within the last year) were asked whether a physician or health care professional had recommended the test in the past year. Physician recommendation was not asked of those who reported that their “doctor didn't order it” or they “don't have doctor”.

Respondents also were asked if they had ever undergone a sigmoidoscopy, colonoscopy, or proctoscopy, with definitions read if requested. Those who answered affirmatively were asked which of the 3 tests they had received most recently (within the last 10 years). The same sequence of questions used for FOBT with regard to timing of the most recent examination, the reason for undergoing the examination, and the reason for not undergoing the examination was asked concerning sigmoidoscopy/colonoscopy/proctoscopy use.

For the majority of the analyses performed, we evaluated the use of CRC tests performed for any indication. Persons with a history of CRC were excluded from all analyses (n = 179). We analyzed only home FOBT because only home tests have been demonstrated to be effective in clinical trials,1, 2, 5-7 and their use is recommended in national guidelines.8-10 We defined an FOBT within the past year as having been performed within the recommended time interval, which is consistent with national guidelines.8-10 We chose the time interval of 10 years as a measure of appropriate endoscopic screening to capture the use of all endoscopic procedures. National guidelines have not been consistent concerning the recommended timing and type of screening endoscopy. Because the wording of the survey questions captured the type and timing of only the most recent of the three possible types of endoscopies, we grouped sigmoidoscopy, colonoscopy, and proctoscopy into the single category of “endoscopy.” Data were analyzed for endoscopies performed within the previous 5 years (data not shown), and the results were similar to those reported herein.

Other Variable Definitions

With regard to race, only “white,” “black,” and “other” were reported because of small sample sizes for other races. “Other” includes American Indian/Alaska Native, Asian, Native Hawaiian, and other Pacific Islander. Race was imputed by the NCHS for the 49 persons with missing race data or who reported multiple race with no main race.11

Although CRC test use questions were asked of respondents age ≥ 40 years, we analyzed only data from respondents age ≥ 50 years because CRC screening guidelines target average-risk persons age ≥ 50 years.8-10 We also grouped persons by age < 65 years or age ≥ 65 years to assess the association between Medicare coverage and CRC test use.

Persons who reported the emergency department as their only usual source of care were included among those with no usual source of care.

With regard to mammography and Papanicolau (Pap) testing, appropriate intervals were defined according to U.S. Preventive Services Task Force guidelines, including mammography within 2 years after age 40 years and Pap smear testing within 3 years after age 18 years.12, 13

The following formula was used to calculate metabolic equivalents (METS) from the number of minutes per week of moderate and vigorous exercise: 4.5 × moderate minutes per week + 7.0 × vigorous minutes per week.14 Physical activity was defined as no activity (METS = 0), some activity (METS = 1–< 675), or meets/exceeds recommendations (METS ≥ 675) according to the Surgeon General's recommendation of 30 minutes of moderate activity per day at least 5 days a week.15

Consistent with national guidelines,16 fruit and vegetable intake was dichotomized as fewer than five or five or more servings per day. An algorithm developed at the National Cancer Institute17 was used to categorize the fruit and vegetable information into categories consistent with these amounts.

Statistical Analysis

Screening rates with 95% confidence intervals (95% CIs) were calculated using SAS (version 8.2)18 and SUDAAN (version 8.0)19 software to account for the complex survey design and to allow for weighting. Screening rates were age-standardized to the 2000 U.S. standard million population using the direct method.20

Respondents who refused or did not know the answer to a question were excluded from analysis of the specific question. The total number of respondent refusals or unknowns (for respondents age ≥ 50 years with no history of CRC) was 7.4%, 8.0%, 6.7%, and 7.1%, respectively, for questions regarding FOBT ever, FOBT recently, endoscopy ever, and endoscopy recently.

Multivariate logistic regression was used to determine the independent variables associated with each of the three endpoints: FOBT within the previous year, endoscopy (sigmoidoscopy/colonoscopy/proctoscopy) within the past 10 years, and either FOBT within the previous year and/or endoscopy within the past 10 years. Additional models were designed to determine whether either mammography or Pap smear tests were associated with CRC test use among women. Two additional models compared screening test versus no test and nonscreening test versus no test. Variables were included in the multivariate models if they have been previously associated with CRC or CRC screening, if they appeared to be associated with test use based on descriptive tables, or if they varied according to test indication. All modeling results are presented as odds ratios (ORs) with 95% CIs.

RESULTS

In 2000, the overall age-adjusted percentages of respondents who reported ever having undergone CRC tests for any reason were 36.7% (95% CI, 35.6–37.8%) for home FOBT, 38.1% (95% CI, 37.1–39.2%) for endoscopy, and 54.2% (95% CI, 53.1–55.2%) for either 1 or both tests.

With regard to tests used for screening versus nonscreening purposes, 88.3% (95%CI, 86.6–90.0%) of FOBT tests performed within the past year were performed for screening and 11.7% (95% CI, 10.0–13.4%) were performed for nonscreening purposes. With regard to endoscopy performed within the past 10 years, 60.8% (95%CI, 59.0–62.7%) were performed for screening and 39.2% (95%CI, 37.3–41.0%) were performed for nonscreening purposes.

For CRC tests performed for all reasons combined (screening and nonscreening), 17.1% of respondents reported undergoing a home FOBT within the past year, 33.9% reported undergoing an endoscopy within the previous 10 years, and 42.5% reported undergoing 1 or the other test within the recommended time intervals (Table 1). With regard to FOBT, test rates increased with increasing age until ages 70–79 years and then decreased. Persons age ≥ 65 years were more likely to report having undergone an FOBT compared with persons ages 50–64 years. White, non-Hispanic, and married persons were more likely to report having undergone a CRC test than black, Hispanic, or unmarried persons. Those who had private health insurance, Medicare or Medi-GAP, or a combination of private insurance and Medicare had higher rates of FOBT use than those with other public insurance or no insurance. Having a usual source of care and the frequency with which the respondent reported seeing a physician were both associated with higher reported test rates. Patterns of associations for endoscopy were similar to those for FOBT use, with the exception that being male was associated with higher rates of endoscopy.

Table 1. Percentage of Respondents Age ≥ 50 Years Who Reported Undergoing CRC cancer Tests within Recommended Time Intervals by Sociodemographic, Healthcare Access, and Health Behavior Characteristics, NHIS, 2000a
FOBT within previous year Endoscopyb within previous 10 years Either test within recommended time interval
No.c % (95% CI) No. % (95% CI) No. % (95% CI)
Total 11,480 17.1 (16.3–17.9) 11,588 33.9 (32.9–35.0) 11,468 42.5 (41.4–43.5)
Gender
 Male 4791 16.8 (15.5–18.0) 4814 37.4 (35.8–39.1) 4786 44.5 (42.9–46.1)
 Female 6689 17.5 (16.4–18.6) 6774 31.1 (29.9–32.4) 6682 41.0 (39.7–42.4)
Raced
 White 9536 17.6 (16.7–18.5) 9615 35.0 (33.9–36.1) 9534 43.6 (42.5–44.7)
 Black 1420 14.6 (12.4–16.7) 1441 29.7 (26.9–32.5) 1414 37.8 (34.9–40.7)
 Other 524 11.6 (8.0–15.1) 532 21.6 (17.7–25.6) 520 28.7 (24.5–33.0)
Hispanic or Latino
 No 10,231 17.6 (16.8–18.5) 10,329 34.6 (33.5–35.7) 10,221 43.4 (42.3–44.4)
 Yes 1249 9.8 (7.6–12.0) 1259 24.0 (21.0–26.9) 1247 29.9 (26.4–33.3)
Age (group) (yrs)
 50–59 4382 14.7 (13.5–15.9) 4418 27.0 (25.4–28.6) 4387 35.5 (33.9–37.2)
 60–69 3129 17.8 (16.3–19.3) 3151 37.7 (35.7–39.7) 3124 45.9 (43.8–48.0)
 70–79 2649 22.6 (20.5–24.6) 2665 42.3 (40.1–44.4) 2640 52.3 (50.1–54.5)
 ≥ 80 1320 14.1 (11.9–16.3) 1354 34.1 (31.2–37.0) 1317 40.7 (37.6–43.9)
Age by Medicare enrollment status (yrs)
 50–64 6008 15.2 (14.2–16.2) 6059 29.4 (28.1–30.8) 6016 37.6 (36.2–39.0)
 ≥ 65 5472 19.7 (18.3–21.0) 5529 39.6 (38.0–41.2) 5452 48.7 (47.1–50.4)
Education
 < 2 yrs 3058 11.6 (10.3–13.0) 3089 24.3 (22.5–26.1) 3041 31.4 (29.5–33.3)
 High school graduate 3605 16.0 (14.7–17.3) 3639 31.3 (29.6–33.1) 3598 40.2 (38.3–42.0)
 Some college 2563 19.5 (17.8–21.3) 2587 37.2 (35.2–39.2) 2567 46.2 (44.1–48.3)
 College graduate 2160 23.0 (20.6–25.4) 2176 45.9 (43.5–48.3) 2165 54.0 (51.5–56.5)
Annual household income
 < $20,000 3694 13.2 (11.7–14.7) 3728 27.7 (25.6–29.7) 3677 35.2 (33.0–37.3)
 $20,000–34,999 1789 17.7 (15.7–19.6) 1793 32.2 (29.5–34.9) 1780 41.1 (38.4–43.7)
 $35,000–54,999 1492 17.7 (15.5–19.9) 1497 35.4 (32.6–38.3) 1492 44.1 (41.0–47.3)
 $55,000–74,999 826 21.8 (18.0–25.6) 833 36.9 (32.1–41.7) 828 46.6 (42.0–51.2)
 ≥ $75,000 1323 23.9 (20.7–27.0) 1340 46.9 (43.2–50.6) 1333 56.6 (52.8–60.3)
Marital status
 Marriede 5905 18.5 (17.4–19.7) 5956 37.1 (35.7–38.6) 5909 46.3 (44.9–47.7)
 Unmarriedf 5553 14.9 (13.8–15.9) 5609 29.1 (27.7–30.5) 5536 36.6 (35.0–38.1)
Health care coverage
 Private onlyg 4696 18.3 (15.5–21.2) 4743 36.0 (32.5–39.5) 4709 44.4 (41.0–47.8)
 Medicare/Medi-GAP 1700 16.0 (12.2–19.8) 1727 32.2 (27.3–37.1) 1695 40.0 (34.8–45.1)
 Private + Medicare/Medi-GAP 3114 18.5 (13.2–23.8) 3149 42.8 (35.8–49.8) 3114 50.1 (44.4–55.8)
 Other/multiple carriersh 1134 14.2 (11.4–17.0) 1129 29.4 (26.2–32.5) 1114 37.8 (34.4–41.2)
 None 796 10.7 (5.2–16.2) 800 12.8 (6.1–19.4) 796 18.1 (11.2–24.9)
Usual source of care
 No 875 5.1 (3.4–6.9) 878 14.4 (11.6–17.2) 871 17.8 (14.9–20.8)
 Yes 10,603 18.0 (17.1–18.9) 10,708 35.3 (34.2–36.4) 10,595 44.2 (43.2–45.3)
No. of physician visits in last year
 None 1359 3.1 (1.9–4.2) 1362 13.2 (11.1–15.2) 1353 14.8 (12.6–17.0)
 1 1414 16.8 (14.4–19.1) 1431 27.7 (25.2–30.3) 1413 36.2 (33.3–39.1)
 2–5 4791 18.3 (17.0–19.5) 4834 35.1 (33.5–36.6) 4780 44.6 (43.0–46.3)
 ≥ 6 3850 21.1 (19.6–22.6) 3888 41.7 (40.0–43.5) 3853 51.7 (49.9–53.5)
General health status
 Excellent/good 8941 17.6 (16.6–18.5) 9031 33.9 (32.8–35.1) 8945 42.6 (41.4–43.8)
 Fair/poor 2527 16.2 (14.4–18.0) 2544 34.1 (32.1–36.1) 2511 42.4 (40.1–44.7)
BMI (kg/m2)
 Normal (< 25) 4149 16.9 (15.7–18.1) 4201 31.9 (30.2–33.6) 4144 40.5 (38.7–42.2)
 Overweight (25–29) 4316 17.0 (15.6–18.4) 4340 35.7 (34.1–37.4) 4310 43.6 (41.9–45.3)
 Obese (≥ 30) 2671 17.7 (16.1–19.3) 2696 35.2 (33.0–37.4) 2676 44.3 (42.1–46.5)
Personal history of cancerd
 No 10,100 16.5 (15.7–17.4) 10,203 32.0 (30.9–33.1) 10,086 40.6 (39.5–41.7)
 Yes 1380 21.2 (18.5–23.8) 1385 46.5 (43.4–49.6) 1382 55.1 (51.8–58.3)
Family history of CRC
 No 9886 17.2 (16.3–18.1) 9963 32.5 (31.4–33.6) 9879 41.4 (40.2–42.5)
 Yes 921 19.2 (16.5–22.0) 923 54.0 (50.8–57.2) 919 59.7 (56.5–62.8)
Family history of Non CRC
 No 5310 16.7 (15.4–17.9) 5345 29.7 (28.3–31.2) 5296 38.5 (37.0–40.1)
 Yes 5486 17.9 (16.8–19.1) 5530 38.2 (36.8–39.7) 5491 46.8 (45.3–48.2)
Mammogram within past 2 yrs
 No 1860 6.1 (4.7–7.4) 1884 14.9 (13.0–16.7) 1850 19.1 (17.0–21.2)
 Yes 4736 21.9 (20.5–23.2) 4794 37.5 (35.9–39.1) 4745 49.2 (47.6–50.9)
Pap smear test within past 3 yrs
 No 1778 8.4 (6.7–10.0) 1807 19.4 (17.2–21.6) 1776 24.1 (21.6–26.7)
 Yes 4767 20.8 (19.5–22.1) 4809 35.5 (34.0–36.9) 4764 46.8 (45.2–48.3)
Physical activity
 None 5495 13.2 (12.2–14.2) 5549 27.7 (26.2–29.2) 5472 35.3 (33.8–36.7)
 Some 2121 18.1 (16.5–19.8) 2140 36.0 (33.8–38.3) 2124 44.7 (42.3–47.1)
 Meet/exceed Recommendations 3508 22.7 (20.9–24.4) 3536 41.5 (39.5–43.6) 3517 51.2 (49.2–53.3)
Fruit/vegetables
 < 5 servings/day 6432 15.7 (14.6–16.7) 6493 32.2 (30.9–33.5) 6432 40.4 (39.0–41.8)
 5+ servings/day 4466 19.3 (17.9–20.7) 4495 37.0 (35.3–38.6) 4462 45.8 (44.1–47.4)
Cigarette smoking
 Never 5515 16.7 (15.5–17.8) 5571 32.6 (31.1–34.1) 5506 41.3 (39.8–42.9)
 Former 3908 19.5 (18.0–20.9) 3945 39.0 (37.4–40.7) 3915 48.2 (46.5–49.9)
 Current 2043 14.5 (12.2–16.8) 2053 28.0 (25.4–30.5) 2031 35.3 (32.6–38.0)
Alcohol use
 None 5725 14.9 (13.8–15.9) 5783 30.6 (29.2–32.0) 5706 38.6 (37.2–40.0)
 1–14 drinks/week 5009 19.7 (18.4–21.1) 5052 37.8 (36.4–39.2) 5016 47.2 (45.8–48.7)
 ≥ 14 drinks/week 549 18.6 (15.0–22.2) 551 37.2 (32.6–41.9) 549 43.7 (39.0–48.5)
  • CRC: colorectal cancer; NHIS: National Health Interview Survey; FOBT: fecal occult blood test; 95% CI: 95% confidence interval; BMI: body mass index; Pap: Papanicolaou.
  • a 2000 estimates age-adjusted to 2000 U.S. Bureau of the Census Decennial Census.
  • b Sigmoidoscopy, colonoscopy, or proctoscopy.
  • c Sample size for each question.
  • d Persons of multiple race who selected a main race are coded according to the main race; “Other” racial category includes American Indian/Alaska Native, Asian, Native Hawaiian and other Pacific Islander.
  • e Includes married and living with partner.
  • f Includes divorced/separated, widowed, never married.
  • g Includes private health insurance from employer, private health insurance purchased directly, and Civilian Health and Medical Programs of Uniformed Services (CHAMPUS).
  • h Includes Medicaid; Indian Health Service, state-sponsored health plan, other government program, military health care/Veterans Administration, any combination of private or Medicare.
  • i Excludes persons with a history of colorectal cancer.

Those respondents with a personal or family history of cancers other than CRC or a family history of CRC were more likely to report having undergone endoscopy than those without such a history. Women who underwent a mammogram or Pap smear test within recommended intervals were more likely to report having undergone CRC tests compared with those who did not. Persons who exercised regularly reported higher rates of test use for all CRC tests evaluated. Former cigarette smokers reported higher test rates compared with never-smokers or current smokers.

Adjusted patterns of association were similar to unadjusted rates, with some exceptions (Table 2). Women were more likely to have undergone an FOBT compared with men. Race was no longer found to be a predictor of FOBT use. The strongest association was noted with the number of times the respondent had seen a physician. Compared with respondents who reported no physician visits in the past year, the odds of having undergone a FOBT were nearly sevenfold higher for respondents who reported greater than six physician visits in the preceding year. Having a usual source of care and having undergone a recent mammogram or Pap test also were found to be strongly associated with FOBT use (OR = 2.05, 3.06, and 2.24, respectively).

Table 2. Association between Selected Characteristics and FOBT and Sigmoidoscopy/Colonoscopy/Proctoscopy, NHIS, 2000a
Characteristic FOBT within past year (n = 10,370) Endoscopy within past 10 years (n = 10,438) Either test within recommended time interval (n = 10,362)
OR (95% CI) OR (95% CI) OR (95% CI)
Genderb
 Male 1.0 (Reference) 1.0 (Reference) 1.0 (Reference)
 Female 1.15 (1.00–1.32) 0.77 (0.69–0.86) 0.89 (0.80–0.99)
Raceb
 White 1.0 1.0 1.0
 Black 1.06 (0.86–1.30) 1.09 (0.94–1.27) 1.08 (0.93–1.24)
 Other 0.80 (0.54–1.18) 0.62 (0.45–0.85) 0.67 (0.50–0.92)
Hispanic or Latinob
 No 1.0 1.0 1.0
 Yes 0.69 (0.53–0.92) 1.03 (0.85–1.26) 0.92 (0.75–1.12)
Age (group) (yrs)b
 50–59 1.0 1.0 1.0
 60–69 1.28 (1.07–1.53) 1.56 (1.35–1.79) 1.45 (1.26–1.67)
 70–79 1.61 (1.25–2.06) 1.71 (1.42–2.06) 1.69 (1.41–2.03)
 ≥ 80 1.08 (0.80–1.45) 1.42 (1.14–1.77) 1.25 (1.01–1.56)
Educationb
 < 12 yrs 1.0 1.0 1.0
 High school graduate 1.23 (1.02–1.48) 1.29 (1.12–1.49) 1.27 (1.11–1.46)
 Some college 1.46 (1.20–1.78) 1.55 (1.32–1.81) 1.53 (1.31–1.77)
 College graduate 1.64 (1.34–2.01) 1.93 (1.63–2.29) 1.83 (1.55–2.16)
Marital statusb
 Married 1.0 1.0 1.0
 Unmarried 0.87 (0.76–0.99) 0.86 (0.77–0.95) 0.80 (0.72–0.89)
Health care coverageb
 Private only 1.39 (0.94–2.04) 1.71 (1.27–2.30) 1.66 (1.28–2.15)
 Medicare/Medi-GAP 1.52 (1.00–2.32) 1.72 (1.23–2.40) 1.82 (1.35–2.45)
 Private + Medicare/Medi-GAP 1.43 (0.95–2.15) 1.98 (1.43–2.74) 1.93 (1.44–2.59)
 Other 1.34 (0.85–2.12) 1.68 (1.20–2.34) 1.69 (1.23–2.32)
 None 1.0 1.0 1.0
Usual source of careb
 No 1.0 1.0 1.0
 Yes 2.05 (1.41–2.98) 1.52 (1.17–1.98) 1.65 (1.30–2.09)
No. of physician visits in last yearb
 None 1.0 1.0 1.0
 1 5.03 (3.26–7.75) 1.92 (1.50–2.45) 2.40 (1.91–3.03)
 2–5 5.52 (3.68–8.29) 2.56 (2.05–3.19) 3.30 (2.67–4.07)
 ≥ 6 6.97 (4.63–10.48) 3.56 (2.85–4.45) 4.68 (3.78–5.80)
General health statusb
 Excellent/good 1.0 1.0 1.0
 Fair/poor 1.04 (0.88–1.22) 1.09 (0.96–1.24) 1.07 (0.94–1.22)
BMI (kg/m2)b
 Normal (< 25) 1.0 1.0 1.0
 Overweight (25–29) 0.99 (0.87–1.14) 1.10 (0.98–1.23) 1.07 (0.96–1.20)
 Obese (≥ 30) 1.07 (0.92–1.25) 1.09 (0.95–1.25) 1.11 (0.98–1.27)
Personal history of cancerb
 No 1.0 1.0 1.0
 Yes 1.09 (0.92–1.30) 1.52 (1.32–1.75) 1.42 (1.24–1.63)
Family history of CRCb
 No 1.0 1.0 1.0
 Yes 1.10 (0.90–1.34) 2.32 (1.98–2.72) 2.04 (1.73–2.40)
Family History of Non-CRCb
 No 1.0 1.0 1.0
 Yes 1.01 (0.89–1.15) 1.27 (1.14–1.41) 1.24 (1.12–1.37)
Mammogram within 2 yrsc
 No 1.0 1.0 1.0
 Yes 3.06 (2.36–3.96) 2.55 (2.12–3.07) 2.96 (2.50–3.50)
Pap test within 3 yrsd
 No 1.0 1.0 1.0
 Yes 2.24 (1.81–2.78) 2.06 (1.72–2.46) 2.41 (2.03–2.86)
Physical activityb
 None 1.0 1.0 1.0
 Moderate 1.25 (1.06–1.47) 1.25 (1.07–1.46) 1.25 (1.09–1.45)
 Meet/exceed Recommendations 1.63 (1.41–1.88) 1.55 (1.36–1.77) 1.64 (1.45–1.86)
 Recommendations
Cigarette smokingb
 Never 1.0 1.0 1.0
 Former 1.16 (1.01–1.33) 1.15 (1.02–1.28) 1.17 (1.05–1.30)
 Current 0.93 (0.76–1.15) 0.82 (0.70–0.96) 0.82 (0.70–0.95)
Alcohol useb
 None 1.0 1.0 1.0
 1–14 drinks/week 1.13 (0.99–1.30) 1.09 (0.98–1.22) 1.14 (1.03–1.26)
 ≥ 14 drinks/week 1.21 (0.92–1.61) 0.98 (0.77–1.25) 0.97 (0.77–1.23)
  • FOBT: fecal occult blood test; NHIS: National Health Interview Survey; OR: odds ratio; 95% CI: 95% confidence interval; BMI: body mass index; CRC: colorectal cancer; Pap: Papanicolaou.
  • a 2000 estimates age-adjusted to 2000 US Bureau of the Census Decennial Census.
  • b Odds ratios adjusted for all other variables except mammography and Papanicolaou test use.
  • c Odds ratio for mammography use adjusted for all variables except gender and Papanicolaou test use; n = 5904 (fecal occult blood test); n = 5964 (endoscopy); and n = 5906 (either test).
  • d Odds ratio for Papanicolaou test use adjusted for hysterectomy status as well as adjusted for all other variables except gender and mammography use; n = 5858 (fecal occult blood test); n = 5911 (endoscopy); and n = 5859 (either test).

There was no significant difference noted with regard to endoscopy use between blacks and whites, but persons of “other” race were less likely to have undergone an endoscopy or either test. The association between ethnicity and endoscopy use or the use of either test disappeared when controlling for other factors. Again, the strongest associations were observed with the number of times the respondent had seen a physician; compared with respondents who reported no physician visits in the past year, the odds of having undergone an endoscopy was nearly fourfold higher for respondents who reported greater than six physician visits and nearly fivefold higher for those reporting undergoing either test. For persons with a family history of CRC, the odds of having undergone an endoscopy within the past 10 years were almost 2.5 times higher than for those without such a history.

The most common reason cited for not having undergone FOBT or endoscopy was lack of awareness of the need for screening (“never thought about it”), followed by lack of recommendation by the physician (“doctor didn't order” the test) (Table 3). Other commonly cited reasons also suggested a lack of awareness of the need for the test (“didn't need it, ” “haven't had any problems, ” “put it off”). Few respondents cited cost, pain/unpleasantness/embarrassment, or having undergone another type of colorectal examination as their reasons for not undergoing CRC tests. Cost and pain/unpleasantness/embarrassment were more likely to be associated with not having undergone endoscopy than with not having undergone FOBT, whereas having undergone another type of colorectal examination was more commonly a barrier to FOBT than endoscopy. Between 4–7% of respondents who did not undergo CRC testing had been advised by a physician to do so. Respondents ages 50–64 years were more likely to report that a physician recommended the test, more likely to report that they had not had any problems, and more likely to put the test off compared with those age ≥ 65 years.

Table 3. Reasons for Never Undergoing Colorectal Examinations or for Undergoing Tests beyond the Recommended Time Interval (NHIS) by Ages 50–64 Years and ≥ 65 Years, 2000a
FOBT Endoscopyb
Age 50–64 yrs Age ≥ 65 yrs Aged 50–64 yrs Aged ≥ 65 yrs
No.c % (95% CI) No. % (95% CI) No.c % (95% CI) No. % (95% CI)
Reason for not undergoing CRC tests
 Never thought about it 2695 52.0 (50.3–53.7) 2247 50.7 (48.6–52.7) 2218 49.7 (47.8–51.7) 1727 50.7 (48.4–53.0)
 Doctor didn't order it 1038 20.8 (19.4–22.2) 1124 25.6 (23.9–27.4) 872 21.0 (19.5–22.4) 776 22.6 (20.8–24.5)
 Didn't need it 593 12.2 (11.0–13.3) 558 12.5 (11.3–13.8) 490 12.1 (10.8–13.3) 444 12.9 (11.5–14.3)
 Have not had any problems 404 8.1 (7.0–9.1) 303 6.7 (5.8–7.7) 439 10.3 (9.1–11.6) 311 9.3 (8.0–10.6)
 Put it off 120 2.6 (2.1–3.1) 44 1.1 (0.7–1.4) 88 2.1 (1.6–2.6) 29 1.0 (0.6–1.5)
 Too expensive/no insurance 51 0.7 (0.5–0.9) 7 0.1 (0.0–0.2) 72 1.5 (1.0–1.9) 10 0.3 (0.1–0.6)
 Too painful, unpleasant, embarrassing 14 0.3 (0.1–0.4) 13 0.3 (0.1–0.5) 54 1.4 (1.0–1.8) 42 1.1 (0.7–1.5)
 Had another type of colorectal examination 72 1.4 (1.0–1.9) 54 1.3 (0.9–1.6) 12 0.3 (0.1–0.4) 7 0.2 (0.0–0.3)
 Don't have a doctor 23 0.4 (0.2–0.5) 17 0.3 (0.2–0.5) 24 0.5 (0.3–0.7) 15 0.4 (0.2–0.6)
 Other 72 1.5 (1.2–1.9) 54 1.3 (0.9–1.7) 47 1.1 (0.8–1.5) 46 1.4 (0.9–1.8)
Doctor recommendation in past yeard
 Yes 258 5.9 (5.1–6.7) 162 4.1 (3.4–4.9) 255 7.2 (6.3–8.1) 135 4.8 (3.9–5.6)
 No 4006 94.1 (93.3–94.9) 3838 95.9 (95.1–96.6) 3313 92.8 (91.9–93.7) 2907 95.2 (94.4–96.1)
  • NHIS: National Health Interview Survey; FOBT: fecal occult blood test; 95% CI: 95% confidence interval; CRC: colorectal cancer.
  • a Sigmoidoscopy, colonoscopy, or proctoscopy.
  • b Estimates not adjusted for age.
  • c Sample size for each question.
  • d Only asked of respondents who did not undergo the tests. Those who responded “don't have doctor” and those with no physician visits within the past 12 months were excluded.

In the current study, we only present differences in test use by indication (screening vs. nonscreening) for endoscopy because FOBT is used primarily for CRC screening and not as a diagnostic test. Although women were less likely to undergo endoscopy for screening than men, they were as likely to have undergone the test for nonscreening (Table 4). Black persons were slightly more likely to have undergone screening endoscopies but less likely to receive nonscreening endoscopies compared with white persons. The association between educational attainment and CRC test use was more pronounced for screening than nonscreening. With increasing frequency of physician visits, the odds of having undergone a nonscreening endoscopy increased more dramatically than the odds of having undergone a screening endoscopy. Those persons in fair/poor health were more likely to have undergone a test for nonscreening purposes whereas those in excellent/good health were more likely to have undergone a test for screening purposes. The association between a family history of CRC and having undergone endoscopy was stronger with screening tests than with nonscreening tests. The same pattern was noted for women who reported a recent mammogram or Pap smear test.

Table 4. Association between Selected Characteristics and Endoscopy by Test Indication, NHIS, 2000a
Characteristic Endoscopy
Screeningb (n = 9575) Nonscreeningb (n = 8951)
Genderc
 Male (Reference) (Reference)
 Female 0.58 (0.52–0.65) 0.94 (0.81–1.09)
Racec
 White (Reference) (Reference)
 Black 1.22 (1.01–1.47) 0.65 (0.53–0.81)
 Other 0.62 (0.42–0.92) 0.52 (0.36–0.76)
Hispanic or Latinoc
 No (Reference) (Reference)
 Yes 1.13 (0.89–1.43) 0.89 (0.66–1.19)
Age (group) (yrs)b
 50–59 (Reference) (Reference)
 60–69 1.87 (1.59–2.19) 1.23 (1.01–1.51)
 70–79 2.12 (1.71–2.62) 1.29 (1.02–1.63)
 ≥ 80 1.71 (1.33–2.21) 0.80 (0.61–1.05)
Educationc
 < 12 yrs (Reference) (Reference)
 High school graduate 1.37 (1.15–1.63) 1.32 (1.10–1.60)
 Some college 1.87 (1.56–2.26) 1.49 (1.22–1.82)
 College graduate 2.57 (2.15–3.08) 1.80 (1.43–2.26)
Health care coveragec
 Private only 2.13 (1.49–3.05) 1.63 (1.07–2.48)
 Medicare/Medi-GAP 1.90 (1.28–2.82) 1.67 (1.04–2.69)
 Private + Medicare/Medi-GAP 2.08 (1.42–3.04) 2.37 (1.48–3.79)
 Other 1.52 (0.98–2.35) 1.84 (1.17–2.91)
 None (Reference) (Reference)
Usual source of carec
 No (Reference) (Reference)
 Yes 1.77 (1.29–2.43) 1.50 (1.03–2.19)
No. of physician visits in last yearc
 None (Reference) (Reference)
 1 2.36 (1.79–3.10) 1.52 (1.03–2.23)
 2–5 2.72 (2.14–3.46) 3.19 (2.30–4.41)
 ≥ 6 3.20 (2.50–4.08) 5.20 (3.74–7.23)
General health statusc
 Excellent/good (Reference) (Reference)
 Fair/poor 0.81 (0.69–0.95) 1.29 (1.11–1.50)
Personal history of cancerc
 No (Reference) (Reference)
 Yes 1.45 (1.24–1.70) 1.71 (1.43–2.04)
Family history of CRCc
 No (Reference) (Reference)
 Yes 2.78 (2.35–3.29) 1.69 (1.35–2.12)
Mammogram within 2 yrsd
 No (Reference) (Reference)
 Yes 3.65 (2.89–4.62) 2.11 (1.68–2.65)
Pap smear test within 3 yrse
 No (Reference) (Reference)
 Yes 2.75 (2.23–3.39) 1.56 (1.25–1.95)
  • NHIS: National Health Interview Survey; CRC: colorectal cancer; Pap: Papanicolaou.
  • a 2000 estimates age-adjusted to 2000 U.S. Bureau of the Census Decennial Census.
  • b Versus no test.
  • c Odds ratios adjusted for all other variables except mammography and Papanicolaou smear use.
  • d Odds ratio for mammography use adjusted for all variables except gender and Papanicolaou smear use; n = 5573 (screening) and n = 5345 (nonscreening).
  • e Odds ratio for Papanicolaou test use adjusted for hysterectomy status as well as adjusted for all other variables except gender and mammography; n = 5516 (screening) and n = 5287 (non-screening).

The proportion of persons who used CRC tests was lower than the proportion of the appropriate population who used mammography and Pap smear tests (data not shown).

DISCUSSION

The results of the current study demonstrate that less than half of the U.S. population age ≥ 50 years reported undergoing home FOBT and endoscopy (sigmoidoscopy, colonoscopy, or proctoscopy) within recommended time intervals. Consistent with previously published literature regarding CRC screening, we have shown that test use varies by gender, race, ethnicity, age, education, income, health care coverage, and having a usual source of care.21-26 With the exception of age, the screening behavior patterns observed in the current study data are consistent with the literature with regard to mammography and Pap smear test screening behaviors.27-29 For CRC, test use continues to increase through the eighth decade of life, whereas mammography test use is highest among women in their 60s and then decreases with increasing age.28 We found that practicing other healthy behaviors (including having other cancer screening tests, exercising, and eating larger amounts of fruits and vegetables) was associated with higher rates of test use, which again is consistent with previously published data regarding CRC, breast cancer, and cervical cancer screening test behaviors.21, 27-29

The variable found to be most strongly associated with CRC test use was having seen a physician at least once in the preceding year, a finding that is consistent with earlier studies.30, 31 We reported an increased association with increasing numbers of physician visits during the preceding year. Nonscreening tests were more strongly associated with an increasing frequency of physician visits compared with screening tests, and it may be that the repeated visits were associated with diagnostic testing and were unrelated to CRC screening. However, regardless of test indication, any versus no physician visits increased the likelihood of test use. Three other variables (doctor recommendation, doctor didn't order it, and usual source of care) also illustrated an association between contact with a physician or health care system and CRC test use. We cannot determine causality between physician visits and screening, since the physician visit needs to occur for the CRC test to be ordered or performed.

We reported some associations that to our knowledge were not previously described in national data, including the association between a personal or family history of cancer, a family history of CRC, and marital status. Those with a family history of CRC reported having undergone endoscopy at twice the rate of those persons without such a history.

Overall, more tests were reported for screening than for nonscreening purposes, a finding that is consistent with previous reports.25 The associations between family history of CRC, mammogram or Pap smear use, and educational attainment were found to be stronger for screening test use than nonscreening test use. Black persons underwent screening endoscopy at rates equal to white persons, but appeared to undergo nonscreening endoscopy at lower rates. Women were as likely to report undergoing nonscreening endoscopy but less likely to report undergoing screening endoscopy. These findings suggest an important differential in medical care related to gastroenterologic disease across race and gender. The 2000 NHIS dataset does not allow us to explore whether this differential is explained by patient choice or by health care system factors. However, observations regarding test use according to indication should be treated with caution because we do not know with certainty how familiar the survey respondents were with the reason they received the tests.

To our knowledge, this is the first report from nationally representative data to examine reasons for not undergoing CRC tests. A lack of awareness by the respondent of the need for the test and a lack of recommendation by a physician for the test to be performed were found to be the most commonly reported barriers to undergoing the test. Lack of a physician recommendation clearly was an important barrier; among persons who reported undergoing no CRC testing or none recently, only 5% reported that a physician had recommended CRC testing. These barriers will be addressed in more detail in comparison with barriers from the physician perspective in a separate report (unpublished data).

Our findings regarding the reported use of CRC tests performed for screening and diagnostic purposes combined are consistent with the rates of use of FOBT and sigmoidoscopy or colonoscopy (lower endoscopy) reported in the 2001 Behavioral Risk Factor Surveillance System (BRFSS), a state-based health behavior telephone survey of the U.S. population.32 BRFSS does not ask respondents to distinguish between tests used for screening and diagnostic purposes. In 2001, an estimated 23.5% of BRFSS respondents reported undergoing FOBT within the past 12 months, 43.4% reported undergoing a lower endoscopy within the previous 10 years, and 53.1% reported undergoing 1 or both tests within the recommended time intervals. The slightly higher reported rates of test use in the BRFSS compared with the NHIS most likely reflect differences in sampling, response rates, and survey administration (in-person vs. telephone).

The current analysis has some limitations. NHIS survey data are based on self-report and are not validated through medical record review. Furthermore, because of the design of the survey instrument and probable confusion by respondents between the various endoscopic procedures, leading to possible misclassification, we grouped the use of any endoscopy together. We likely overestimated compliance with guidelines for screening by sigmoidoscopy (recommended every 5 years) by choosing 10 years as the appropriate screening interval for endoscopy. However, choosing 5 years as a measure of appropriate screening would have underestimated compliance with screening guidelines for colonoscopy, and more people reported undergoing colonoscopy than sigmoidoscopy.

The primary challenge for the public health and medical communities regarding the continued low rates of CRC test use is to continue to educate both the public and physicians regarding the importance of screening for this disease. We could not evaluate the influence that physician time pressure and/or the use of reminder systems may have had on the use of CRC tests. At the time of the 2000 NHIS, there was no Health Plan Employer Data Information Set (HEDIS) measure for CRC screening; HEDIS measures and reminder systems for mammography and Pap smear testing have been reported to be effective in helping to increase test utilization.33, 34 A HEDIS measure for CRC has just been accepted, and will likely have an impact on these low rates of test use. Identifying physician incentives to recommend screening, addressing health care coverage of screening tests, and making changes to health systems such as monitoring CRC screening use and using provider and client reminder systems, also should aid in the effort to increase CRC screening. Efforts to reduce disparities in test use across gender, race, ethnicity, income, education, and health care coverage also must be heightened. A previous report using 2000 NHIS data also emphasized disparities according to place of birth.35 Because contact with a physician and having a usual source of care increases the likelihood that a person will obtain a CRC test, ensuring that all persons have access to routine primary medical care would create regular opportunities to recommend screening.