A novel pathway for investigation of colorectal symptoms with colonoscopy or computed tomography colonography

Colorectal cancer (CRC) is a common problem in New Zealand and there is significant pressure on colonoscopy resources. Lower gastrointestinal symptoms are common in the community hence the appropriate selection of patients for colonoscopy is problematic. The Canterbury District Health Board recently developed the Canterbury Colorectal Symptom Pathway (CCrSP) to attempt to improve prioritisation using a combination of presenting clinical features integrated into a scoring tool. This study describes that pathway and its outcomes over a 6-month period.

Following implementation of the CCrSP, all outpatient referrals receiving colonoscopy or Computerised Tomography Colonography (CTC) over a 6-month period were audited. The clinical features included in the referral, waiting time and outcome of investigation were recorded. Using the scoring tool, a score was calculated for all referrals and compared with outcome.

Some 1,369 procedures were performed during the study period. Of the symptomatic patients, 38 CRCs were diagnosed from 633 colonoscopies and 253 CTCs. Individual factors predictive for CRC were rectal bleeding (OR 2.1, 95%CI 1.1-4.2), iron deficiency anaemia (OR 3.2, 95%CI 1.6-6.3) and positive faecal occult blood test (OR 6.1, 95%CI 2.1-16.3). No CRCs were diagnosed in the group scoring below the pre-set threshold for investigation. Multiple logistic regression analysis demonstrated a 1 unit increase in score increased the likelihood of CRC by 7.2% (95%CI 4.4%-10.1%, p<0.001). Of the 11 CRCs suggested by CTC, there was one false positive. The follow up colonoscopy rate after CTC was 11.5% and further radiology was recommended in 7.9%.

The CCrSP pathway was accurate for predicting CRC and offers a reliable triage tool. The scoring tool was both sensitive for CRC and predictive of the risk of CRC in patients who received colonoscopy or CTC.