Replicate and repeat faecal immunochemical tests in symptomatic patients: A systematic review

Faecal Immunochemical tests (FITs) in the assessment of patients presenting with symptoms have generally used a single sample. Little evidence pertains to the use of replicate, where a number of tests are done prior to decision-making or repeat FIT, where additional FIT are performed following clinical decision-making. Overwhelmingly, research has focussed on FIT to help identify colorectal cancer (CRC). The aim of this review is to assess the available literature concerning replicate and repeat FIT in symptomatic patients to help generate consensus and guide future research.

The terms 'faecal immunochemical test' or 'FIT' were combined with 'multiple' or 'repeat'. EMBASE, Medline and PubMed database and other searches were conducted. All papers published in English were included with no exclusion date limits until November 2021.

Of the 161 initial papers screened, seven were included for review. Qualitative and quantitative FIT outcomes were assessed in the studies. The primary aims of most related to whether replicate FIT increased diagnostic yield of CRC, with colonoscopy used as the reference standard. One publication assessed the impact of a new COVID-adapted pathway on CRC detection. No consensus on replicate FIT was apparent. Some concluded that FITs may help minimise missed CRC diagnoses: others showed no increase in diagnostic yield of CRC.

Current evidence on replicate and repeat FIT is both minimal and conflicting. FIT is a superb clinical tool, but significant gaps surrounding application remain. Further studies relating to replicate and repeat FIT are required.