This study is one of the first to examine self-reported CRC testing accuracy for four recommended CRC screening tests in Hispanics compared to other groups. Our study suggests that there are significant differences in self-report measure sensitivity across racial/ethnic groups, but that all groups over-report tests. This finding is in keeping with prior qualitative work in this triethnic population that revealed patients had difficulty distinguishing between different CRC tests and often mentioned upper gastrointestinal tests as CRC tests as well.5
These survey items were designed to address that difficulty but may need further development to address this problem in Hispanics. We found only one study comparing accuracy of self-reported CRC test use in Hispanics with other groups21
and that study was conducted before the widespread dissemination and promotion of the guidelines that began in 199722
and did not examine COL or DCBE. They found no difference in sensitivity or specificity for either FOBT or FS measures. However, they examined only a 2-year time frame, and few FS tests were done in Hispanics. In a recent meta-analysis,23
self-reported accuracy of other types of cancer screening tests were compared across racial/ethnic groups. Mammography and digital rectal exam self-reports were less sensitive and Pap test self-reports were less specific in Hispanics compared to other groups. In our study, we observed better sensitivity for self-report of FOBT, FS and DCBE in African-Americans compared to Hispanics, but we did not observe statistically significant differences in any self-reported CRC test measure between African-Americans and whites. One other recent study comparing CRC self-report accuracy in African-American and white predominantly male veterans also found no differences.9
Our sample estimates of sensitivity and specificity for each of the four tests are in line with other recent studies examining the accuracy of CRC self-report.7
Consistent with our findings, they observed the highest sensitivity for COL recall (0.77–0.92), lowest for BE (0.49–0.74) with intermediate values for FS (0.75–0.87) and FOBT (0.56–0.93). These studies also found that the specificity of the tests varied much less across tests (range 0.72–0.97), and that there was over-reporting for all tests, particularly DCBE.
Strengths of our study include that it is one of the first to examine the accuracy of self-report CRC test use in Hispanics. We maximized the ascertainment of completed tests, through use of multiple sources of chart data, restricting our inclusion criteria to patients in the system for a sufficient length of time to adhere to the guidelines for all of the CRC tests and taking advantage of the relative geographic isolation of the university system that maximized the chances that patients did not go elsewhere for health care. However, there are some limitations of the study. Our response rate was modest at 53%, however, we did determine that our respondents were no different to non-respondents and were representative of the clinic population. Second, because we included only those with access to health care who had medical record availability, our findings should be generalized with caution to other populations and settings. Our estimates, however, were similar to those reported in other studies. Third, we were not able to analyze the characteristics of the Spanish version of the measures because of a small sample size. Fourth, because of our small sample size, we did not control for racial/ethnic group differences in education, income or health status that may have influenced our findings. Although a separate analysis by educational level across all groups showed no differences in sensitivity measures.
Developing surveys items for multiethnic groups is fraught with difficulties24
because responding to a survey is a complex process. It has been conceptualized as involving four different stages, each of which can lead to inaccuracies in reporting. During the ‘comprehension’ stage, the respondent interprets the meaning of the question; in the ‘retrieval’ stage, the respondent relies on long-term memory for relevant information; in the ‘estimation/judgment’ stage, the respondent assesses the information retrieved and its relevance to the question and chooses to accept or reject the information. In the final ‘response stage’, the respondent weighs factors such as sensitivity and social desirability of the responses and then decides what answer to give. Cultural differences among groups could affect the process at any of these stages and may have done so in our population.26
Previous studies have reported ethnic group differences in response style24
and have reported that measures of preventive behaviors are particularly problematic across cultures.25
These measures were cognitively tested but not in Hispanics in the target age group. Future studies should cognitively test measures in all groups and ages.27
The implication of these findings is that national prevalence estimates maybe overstating screening rates in all groups, and that the observed racial/ethnic group differences in test use are real, especially for FOBT, FS and DCBE. Overall the accuracy of these self-report measures is acceptable: with COL self-report displaying the least racial/ethnic variation in accuracy. Since secular trends in CRC test use point to greater use of COL and declining rates of FS FOBT1
in the USA, the prevalence of inaccurate group estimates may be attenuated as COL becomes the preponderant CRC test. However, further challenges in accurately measuring CRC screening test use will remain, such as the addition of new tests to the recommendations.3
Self-report measures of new tests will need to be developed and our work points to the vital importance of cognitive testing of new measures in all population subgroups to enhance understanding of the cultural influences on the cognitive, emotional and judgment processes utilized by survey respondents.