ROLE OF FIT AND CT ABDOMEN-PELVIS IN PRIORITISING DIAGNOSTIC COLONOSCOPY FOR COLORECTAL CANCER

ABSTRACT

Introduction COVID-19 has resulted in many new challenges for healthcare services. Colonoscopy, which is the gold standard investigation for diagnosis of colorectal cancer (CRC), has been significantly impacted with cessation of services during peak corona virus outbreaks with significant backlog. Several strategies have been proposed to address this. One of the main approaches is to risk stratify patients using a quantitative faecal immunochemical test (qFIT) alone or in combination with CT scan. Our study assessed the adherence of Bedford Hospital NHS Foundation Trust in performing both qFIT and CTAP with Iv contrast prior to colonoscopy referral. This study also evaluated the sensitivity of qFIT and CTAP both individually and in combination of missing a cancer when used as a triage service for prioritisation of colonoscopy. Methodology Data was collected retrospectively from all colonoscopies performed in Bedford hospital, from June to August 2020, totalling 470 patients. Results Average patient age was 59.9 years, with an age range of 19 to 90 years old. 55% were males and 45% were females. 45% (210) patients had a FIT performed pre colonoscopy. 129 patients had positive FIT. Overall, 35% (164) of patients underwent CTAP prior to colonoscopy. 125 patients underwent both FIT and CTAP prior to colonoscopy. Individually, FIT had a positive predictive value (PPV) and negative predictive value (NPV) of 6.2% and 98.7% with respect to diagnosing CRC. CTAP had a PPV and NPV of 42.9% and 100%. Performing FIT and CTAP in combination had a PPV and NPV of 28.6% and 100% respectively. Conclusion Sensitivity of single qFIT is low and can miss cancers if used alone. Therefore, it should not be utilised as a single test for triage in community for prioritising colonoscopy in symptomatic patients. The risk of missing a cancer can be reduced by CTAP with Iv contrast as an add on test with negative predictive value of 100%.