Diagnostic performance of a faecal immunochemical test for patients with low-risk symptoms of colorectal cancer in primary care: an evaluation in the South West of England
Menée en Angleterre à partir de données portant sur 3 890 patients ayant consulté en médecine générale pour des symptômes faiblement associés au risque de cancer colorectal (âge : 50 ans ou plus), cette étude évalue la performance, du point de vue de la valeur prédictive positive, de la valeur prédictive négative, de la sensibilité et de la spécificité, d'un test immunochimique de recherche de sang dans les selles pour diagnostiquer la maladie
Background : The faecal immunochemical test (FIT) was introduced to triage patients with low-risk symptoms of possible colorectal cancer in English primary care in 2017, underpinned by little primary care evidence.
Methods : All healthcare providers in the South West of England (population 4 million) participated in this evaluation. 3890 patients aged
≥
50 years presenting in primary care with low-risk symptoms of colorectal cancer had a FIT from 01/06/2018 to 31/12/2018. A threshold of 10
μg Hb/g faeces defined a positive test.
Results
:
Six hundred and eighteen (15.9%) patients tested positive; 458 (74.1%) had an urgent referral to specialist lower gastrointestinal (GI) services within three months. Forty-three were diagnosed with colorectal cancer within 12 months. 3272 tested negative; 324 (9.9%) had an urgent referral within three months. Eight were diagnosed with colorectal cancer within 12 months. Positive predictive value was 7.0% (95% CI 5.1
–9.3%). Negative predictive value was 99.8% (CI 99.5–99.9%). Sensitivity was 84.3% (CI 71.4–93.0%), specificity 85.0% (CI 83.8–86.1%). The area under the ROC curve was 0.92 (CI 0.86–0.96). A threshold of 37
μg Hb/g faeces would identify patients with an individual 3% risk of cancer.
Conclusions
:
FIT performs exceptionally well to triage patients with low-risk symptoms of colorectal cancer in primary care; a higher threshold may be appropriate in the wake of the COVID-19 crisis.
British Journal of Cancer , article en libre accès, 2021