Of 1072 eligible patients identified, 997 (93%) were enrolled in the study, of whom 973 (98%) were successfully followed to the primary end point (completion of a CRC screening strategy or 12 months of follow-up). Enrollment initiated in April 2007, and follow-up was completed March 2010. Details of the study solicitation, enrollment, and follow-up are outlined in . The characteristics of the study participants are presented in . The mean age of the participants was 58.4 years (range, 50–79 years), and 53% were women. The group was racially/ethnically diverse with excellent representation of Latino and Asian patients, and there was no significant difference in participation between racial or ethnic groups. English was the preferred language by 55% of participants, while 27% preferred Spanish and 18% preferred either Cantonese or Mandarin. While the majority had annual incomes of less than $20 000, with 57% having incomes of less than $10 000, 67% had attained a high school diploma or general equivalency diploma, and 39% had attended college. While only 17% stated no insurance, the majority had public insurance including the San Francisco health access plan.
Consolidated Standards of Reporting Trials (CONSORT) diagram. FOBT indicates fecal occult blood testing.
Baseline Sociodemographic Characteristics of the Participants by Study Arm
Within 12 months of enrollment, 58% of participants completed the CRC screening strategy they were assigned or chose. A significantly lower proportion of participants in the colonoscopy arm completed colonoscopy (38.2%) compared with participants in the FOBT arm completing FOBT (67.2%) (P < .001) or participants who were allowed to choose their screening strategy (68.8%) (P < .001) (). Moreover, the proportion of participants who completed either CRC screening strategy after being recommended colonoscopy (58.1%, including those who completed FOBT) was significantly lower compared with participants recommended FOBT or participants who were allowed to choose their screening strategy (67.2% [P = .01] and 68.8% [P = .004], respectively).
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 (more ...)
There were significant differences between racial/ethnic groups with regard to completion of CRC screening strategies. African Americans had the lowest CRC screening completion rate (48.0%), while Asians (60.7%) and Latinos (62.9%) had the highest rates (). Moreover, there were differences between racial/ethnic groups in completion of FOBT vs colonoscopy strategies. Nonwhites were more likely to complete FOBT, while whites were significantly more likely to complete colonoscopy than nonwhites (). Correspondingly, among participants in the Choice arm, completion varied by race/ethnicity, with nonwhites completing FOBT significantly more often and white participants being more likely to complete colonoscopy.
Adherence to Colorectal Cancer Screening Strategiesa
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 (more ...)
Of the 226 participants who underwent colonoscopy, 74 (32.7%) had adenomatous polyps: 34 participants (15.0%) had a single adenoma, 19 (8.4%) had 2, 8 (3.5%) had 3, 7 (3.1%) had 4, and 6 (2.7%) had 5 or more removed. No cancers were detected. Of 8 participants who had positive FOBT test results, 5 underwent colonoscopy and 3 were nonadherent (2 refused colonoscopy and 1 missed her scheduled appointment multiple times).
Several sociodemographic factors were associated with adherence to CRC screening. In addition to age and race/ethnicity, language preference affected adherence (). Participants who preferred to conduct their interviews in Spanish, Cantonese, or Mandarin were significantly more likely to adhere to CRC screening than participants of the same race/ethnicity who preferred to conduct the interview in English. Patients with private or public insurance more often completed screening compared with those without insurance. Patients without high school diplomas had greater adherence than those with diplomas. Clustering by PCP was examined but not found to be significant.
A multivariable model examining the study arm, age, race/ethnicity, and language revealed that completion of CRC screening among participants recommended colonoscopy remained significantly lower than other groups. However, the differences in completion between different race/ethnicity categories were eliminated when language was introduced (). Specifically, participants who preferred to conduct their interview in Cantonese or Mandarin completed screening more often than participants who preferred to speak English. No significant interaction between race/ethnicity and study arm on completion was noted.