Are we doing enough to screen for colorectal cancer? Findings from the 1999 Behavioral Risk Factor Surveillance System

Journal of Family Practice, Sept, 2002 by Laura C. Seeff, Jean A. Shapiro, Marion R. Nadel

* OBJECTIVES To estimate current rates of use of fecal occult blood testing (FOBT) and sigmoidoscopy or colonoscopy; to determine whether test use varies by demographic factors; and to compare 1999 rates of use with 1997 rates.

* STUDY DESIGN The Behavioral Risk Factor Surveillance System is an ongoing, state-based random-digit-dialed telephone survey of the US population that collects various health behavior information, including the use of colorectal cancer (CRC) screening tests.

* POPULATION In 1999, 63,555 persons 50 years of age or older responded to questions regarding FOBT and sigmoidoscopy or colonoscopy.

* OUTCOMES MEASURED The proportion of survey respondents reporting having had FOBT and sigmoidoscopy/colonoscopy at any time; and the proportion reporting having had FOBT and sigmoidoscopy/colonoscopy within recommended time intervals. Data were recorded for the years 1997 and 1999, and analyzed according to various demographic factors.

* RESULTS In 1999, 40.3% of respondents reported having had an FOBT at some time, and 43.8% reported having had a sigmoidoscopy or colonoscopy. Regarding recent test use, 20.6% of respondents reported having had an FOBT within the year, and 33.6% reported having had a sigmoidoscopy or colonoscopy within the past 5 years. Some demographic variation was noted. In 1997, 19.6% reported having had an FOBT within the year, and 30.3% reported having had a sigmoidoscopy or proctoscopy within the past 5 years.

* CONCLUSIONS Use of CRC screening tests increased only slightly from 1997 to 1999. Usage remains low, despite consensus that screening for CRC reduces mortality from the disease. Efforts to promote awareness of, and screening for, CRC must intensify.

* KEYWORDS Colorectal neoplasms, mass screening, occult blood, sigmoidoscopy, colonoscopy. (J Fam Pract 2002; 51:761-766)

KEY POINTS FOR CLINICIANS

* Strong scientific evidence shows that regular colorectal cancer (CRC) screening effectively reduces CRC incidence and mortality.

* Despite this evidence, use of CRC screening tests remains low.

* Clinicians can use available physician-education tools (www.cdc.gov/cancer/colorctl/ calltoaction) to review current screening tests and guidelines and should begin offering regular CRC screening tests to their patients, if they are not already doing so.

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States for men and women combined; for women alone, it follows lung and breast cancers, and for men, it follows lung and prostate cancers. (1) Strong scientific evidence indicates that regular screening is effective in reducing CRC incidence and mortality. (2-8) Randomized controlled trials have demonstrated a reduction in CRC incidence and mortality with annual and biennial fecal occult blood testing (FOBT), and case-control studies have shown a reduction in CRC mortality associated with the use of sigmoidoscopy. Based on this evidence, 3 sets of national guidelines were developed recommending that average-risk persons undergo regular CRC screening with 1 or more of the following tests: FOBT annually, sigmoidoscopy periodically (usually every 5 years), colonoscopy every 10 years, or double-contrast barium enema every 5-10 years. (9-11)

To estimate current use of CRC screening tests, to evaluate variation in test use by demographic factors, and to compare current test use with previously published rates of use, (12) we analyzed data from the 1999 Behavioral Risk Factor Surveillance System (BRFSS) on the use of a home blood stool test (FOBT) and on having had sigmoidoscopy or colonoscopy. Results from the 1999 survey were compared with results from the 1997 survey.

METHODS

In 1999, 50 states, the District of Columbia, and Puerto Rico participated in the BRFSS, a state-based, random-digit-dialed telephone survey of the US non-institutionalized, adult (aged 18 years or older) civilian population. The BRFSS collects a wide variety of health behavior information, including the use of CRC screening tests.

During the survey, 63,555 respondents aged 50 years or older were asked 4 questions regarding their use of the FOBT and their having undergone sigmoidoscopy or colonoscopy (Table 1). Variables not measured in this dataset include use of sigmoidoscopy separately from colonoscopy, test indication, or physician specialty. We analyzed CRC tests used at any time and used recently (FOBT within the past year and sigmoidoscopy or colonoscopy within the past five years).

Aggregated rates, standard errors, and 95% confidence intervals were calculated using SAS (13) and SUDAAN software. (14) Respondents who refused to answer 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 was 1007 (1.6%) for the FOBT questions and 1217 (1.9%) for the sigmoidoscopy questions. Data were weighted, using intercensal estimates, to the sex, racial, ethnic, and age distribution of each state's adult population, and were age-standardized to the 1999 BRFSS population. To compare 1997 and 1999 estimates, the 1997 data were also age-standardized to the 1999 BRFSS population. The median state response rate for the entire survey was 56.7%, calculated using the cooperation rate formula. (15)