One hundred and thirty-two studies were included in the review. Over one hundred and thirty-two studies were included in the review. Overall, 101 studies reported adherance to screening; 11 studies (231,365 patients) examined adherence rates for FOBT re-screening; 22 studies (at least 75,790 patients) reported adherence rates for sigmoidoscopy; 3 studies (at least 8,672 patients) assessed adherence rates for sigmoidoscopy re-screening; and 18 studies (at least 74,677 patients) reported adherence rates following interventions to to increase screening results. The numbers of patients in the remaining studies were not specified in the review.
Percentage adherence to screening with FOBT and to sigmoidoscopy.
The rates of adherence to FOBT ranged from 0 to 89% in the USA and Canada, from 10 to 92% in Europe, and from 2 to 95% in other countries. The rates of adherence to sigmoidoscopy ranged from 2 to 69%. The rates for adherence re-screening (sequential offers to screen) were reported as 'coverage' (completion of at least one test), 'compliance' (completion of all tests among all those offered repeat screens) and 'repeat' (completion of subsequent tests among the subset of those who completed a prior test). The rates for FOBT re-screening were 39 to 90% for coverage, 23 to 60% for compliance, and 56 to 94% for repeats. Adherence to re-screening by sigmoidoscopy ranged from 34 to 79% for coverage and from 16 to 64% for compliance.
Response to interventions to increase adherence.
The adherence rates for the control groups ranged from 17 to 68%. The adherence rates following interventions to increase screening ranged from 0 (physician talk on importance plus written material about screening) to 94% (mailed reminder card, plus 3- to 5-minute talk by the physician on importance).
Correlates of adherence (positive, negative or none).
'Health motivation' was the most consistent positive correlation to FOBT test completion (positive in 7 of the 9 studies). Knowledge of cancer and knowing someone with colorectal cancer also appeared positively correlated. Demographic and medical history variables have not been adequately tested to clearly show statistical differences; however, patients who were female, had a higher education level, or had a higher income, were more likely to complete the FOBT test. With sigmoidoscopy, there were very few studies examining correlates. There were some data to suggest that patients who were male, had a hgher education level, or had a higher income, were more likely to have had sigmoidoscopy. The perceived susceptibility to colorectal cancer was also positively correlated with having had a sigmoidoscopy (all 3 studies were positive).
Reasons for nonadherence.
The reasons given for nonadherence to the FOBT included:
practical reasons;
no current health problems;
the test was embarrassing or unpleasant; and
the patient did not want to know of any health problems.
The reasons given for nonadherence to the sigmoidoscopy test were:
no current health problems;
practical reasons;
worry about pain or complications of the test; and
the patient did not want to know of any health problems.