Adherence to colorectal cancer screening: a randomized clinical trial of competing strategies

Abstract

Background: Despite evidence that several colorectal cancer (CRC) screening strategies can reduce CRC mortality, screening rates remain low. This study aimed to determine whether the approach by which screening is recommended influences adherence.

Methods: We used a cluster randomization design with clinic time block as the unit of randomization. Persons at average risk for development of CRC in a racially/ethnically diverse urban setting were randomized to receive recommendation for screening by fecal occult blood testing (FOBT), colonoscopy, or their choice of FOBT or colonoscopy. The primary outcome was completion of CRC screening within 12 months after enrollment, defined as performance of colonoscopy, or 3 FOBT cards plus colonoscopy for any positive FOBT result. Secondary analyses evaluated sociodemographic factors associated with completion of screening.

Results: A total of 997 participants were enrolled; 58% completed the CRC screening strategy they were assigned or chose. However, participants who were recommended colonoscopy completed screening at a significantly lower rate (38%) than participants who were recommended FOBT (67%) (P < .001) or given a choice between FOBT or colonoscopy (69%) (P < .001). Latinos and Asians (primarily Chinese) completed screening more often than African Americans. Moreover, nonwhite participants adhered more often to FOBT, while white participants adhered more often to colonoscopy.

Conclusions: The common practice of universally recommending colonoscopy may reduce adherence to CRC screening, especially among racial/ethnic minorities. Significant variation in overall and strategy-specific adherence exists between racial/ethnic groups; however, this may be a proxy for health beliefs and/or language. These results suggest that patient preferences should be considered when making CRC screening recommendations. Trial Registration clinicaltrials.gov Identifier: NCT00705731.

Figure 1

Consolidated Standards of Reporting Trials (CONSORT) diagram. FOBT indicates fecal occult blood testing.

Figure 2

Completion rates by study arm. Participants recommended colonoscopy completed screening at a significantly lower rate than participants recommended fecal occult blood testing (FOBT) or a choice between colonoscopy or FOBT. The level of statistical significance was reduced to .01 to adjust for multiple comparisons.

Figure 3

Adherence by study arm and race/ethnicity. Among participants offered a choice of screening tests, white participants adhered more often to colonoscopy than nonwhite participants (odds ratio [OR], 3.2; 95% CI, 1.7–6.1), and less often to fecal occult blood testing (FOBT) (OR, 0.3; 95% CI, 0.1–0.6). Among participants offered FOBT, Asians (OR, 2.6; 95% CI, 1.2–5.3) and Latinos (OR, 2.1; 95% CI, 1.0–4.2) adhered more often than whites.