Faecal occult blood screening for colorectal neoplasia: a randomized trial of three days or six days of tests.

Haemoccult, a guaiac test for faecal occult blood, detects 56-78 per cent of asymptomatic carcinomas when performed over 3 days. In patients with known colorectal cancer the sensitivity of the test for neoplasia is increased by extending the test period to 6 days. We report the first randomized comparison of 3 day with 6 day testing in asymptomatic individuals. 35,184 age and sex matched individuals were randomly allocated to receive Haemoccult over 3 or 6 days. The tests were completed by 10,176 (57.8 per cent) of the 17,616 offered 3 day Haemoccult and 9461 (53.9 per cent) of the 17,568 offered 6 day Haemoccult, a significant decrease in compliance (P less than 0.001). Of the 3 day Haemoccult tests 131 (1.29 per cent) were positive, significantly fewer than the 160 (1.69 per cent) positive tests after 6 day Haemoccult (0.01 less than P less than 0.02). Investigation of subjects with a positive test revealed 20 carcinomas (1.14 per 1000 offered and 1.97 per 1000 completing the test) in the 3 day group and 24 carcinomas (1.37 per 1000 offered and 2.54 per 1000 completing the test) after 6 day Haemoccult tests (0.5 less than P less than 0.7 for those offered the test and 0.3 less than P less than 0.5 for those completing it). After 3 day Haemoccult 112 adenomas in 76 persons were detected (4.31 per 1000 offered and 7.47 per 1000 completing the test). In the 6 day group 123 adenomas in 83 persons (4.72 per 1000 offered and 8.77 per 1000 completing the test) were detected (0.5 less than P less than 0.7 for those offered the test and 0.3 less than P less than 0.5 for those completing it). Large adenomas were found in 27 individuals after 3 day testing (1.53 per 1000 offered the test and 2.65 per 1000 completing it) and in 35 individuals after 6 day testing (1.99 per 1000 offered the test and 3.70 per 1000 completing it) (0.3 less than P less than 0.5 for those offered the test and 0.1 less than P less than 0.2 for those completing it). This study has not demonstrated a significant increase in the yield of neoplasia in asymptomatic subjects offered Haemoccult over 6 days. However there was a significant decrease in compliance and a higher rate of colonscopy in those offered 6 day testing.

RCT Entities:   Population Interventions Outcomes