Evaluation of the Danish national strategy for selective use of colonoscopy in symptomatic outpatients without known risk factors for colorectal cancer

Objective. A diagnostic strategy implemented in Denmark in 2002 recommends selective use of colonoscopy in outpatients without known colorectal cancer (CRC) risk factors who are referred with symptoms consistent with possible CRC. Selection of patients for colonoscopy was based on the presenting symptom(s) and findings at the initial examination (flexible sigmoidoscopy/faecal occult blood test). The aim of this study was to evaluate the strategy by assessing the prevalence of patients with diagnosed CRC, the frequency of patients with missed CRC, the adherence to the strategy and the number of examinations performed. Material and methods. We prospectively studied patients aged 40 years and older without known risk factors for CRC, referred to two surgical outpatient clinics during a period of 15-16 months. Examinations, findings at the examinations, the final diagnoses and date of discharge were recorded. Missed CRCs were identified by follow-up in hospital discharge registries. Results. CRC was diagnosed in 126 (5.3%; 95% CI: 4.5-6.3%) of the 2361 patients included during the diagnostic work-up. Two additional cancers identified at follow-up were both missed during colonoscopy (1.5%; 95% CI: 0.2-5.4%). The adherence to the strategy was 75.7%, and 125 of the 126 patients with a CRC were examined in conformity with the recommended strategy. Almost 60% of the patients underwent colonoscopy and almost 50% underwent both flexible sigmoidoscopy and colonoscopy. Conclusions. The diagnostic strategy is an acceptable alternative to initial colonoscopy, with a low probability of missing a CRC; however, a considerable proportion of the patients undergo colonoscopy and multiple examinations.