The immunochemical faecal occult blood test leads to higher compliance than the guaiac for colorectal cancer screening programmes: a cluster randomized controlled trial.
BACKGROUND
We conducted a cluster-randomized trial aimed at assessing the effect of the type of faecal occult blood, guaiac or immunochemical test on screening compliance.


METHODS
We sampled 130 general practitioners (GPs) who consented to participate in the trial. We randomly allocated half of them to the guaiac (Hemo-Fec) and half to the immunochemical test (OC-Hemodia). We sampled 2/10 of the GPs' 50-75-year-old patients (n=7332) and randomly divided this population into half. One half was invited to be screened at the GP's office and the other to the nearest gastroenterology ward. The principal outcome was the percentage of returned tests.


RESULTS
The immunochemical test had a compliance of 35.8% and the guaiac of 30.4% (relative risk [RR] 1.20; 95% confidence interval [CI] 1.02-1.44). The difference was mostly due to a higher probability of returning the sample: 93.8% and 88.6% for immunochemical and guaiac, respectively (RR 1.06; 95% CI 1.02-1.10). The guaiac test had a higher prevalence of positives (10.3% versus 6.3%, RR 0.603; 95% CI 0.433-0.837). There was a higher variability in the results obtained with the guaiac test compared with the immunochemical (F[1, 12] = 16.25; P=0.0017).


CONCLUSIONS
Compliance is more likely with the immunochemical than the guaiac test, independent of the provider. Guaiac tests show a higher variability of the results among centres. The successful implementation of a screening programme requires a period of standardization of the test reading in order to avoid unexpected work overload for colonoscopy services.
Federici
Antonio
A
Agency for Public Health, Lazio Region, Via di S. Costanza 53, 00198 Rome, Italy.
Giorgi Rossi
Paolo
P
Borgia
Piero
P
Bartolozzi
Francesco
F
Farchi
Sara
S
Gausticchi
Gabriella
G
D000368:Aged; D016000:Cluster Analysis; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005260:Female; D006138:Guaiac / Q000494:pharmacology*; D006801:Humans; D007120:Immunochemistry; D007202:Indicators and Reagents; D007388:Internal Medicine; D008297:Male; D008403:Mass Screening / Q000191:economics / Q000379:methods*; D008875:Middle Aged; D009780:Occult Blood; D010349:Patient Compliance; D011237:Predictive Value of Tests; D015995:Prevalence; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D007202:Indicators and Reagents; D011933:Reagent Kits, Diagnostic; D006138:Guaiac