The effect of antiplatelet therapy and oral anticoagulants on the accuracy of faecal immunochemical testing.

INTRODUCTION: Faecal immunochemical testing (FIT) has been adopted to identify patients requiring further investigations on the colorectal cancer (CRC) referral pathway. We aimed to investigate the effect of antiplatelet and anticoagulant drugs on the accuracy of FIT results. METHODS: This observational study categorised patients with suspected CRC symptoms, who completed both FIT and colonic investigations, into two groups (control and exposed) based on their use of antiplatelet and anticoagulant drugs. Two-by-two tables and receiver operating characteristic (ROC) curve analysis were used to determine accuracy. RESULTS: A total of 928 patients were divided into a control (n=683) and an exposed group (n=245). A nonsignificant higher proportion of patients tested positive in the exposed group (24.1% vs 18.4%, p=0.063). For detection of CRC, improved sensitivity of 87% vs 81.2%, specificity of 84.8% vs 79.9% and negative predictive value of 99.2% vs 98.3% was calculated in the control vs exposed groups, respectively. The positive predictive value was comparable between the two groups (21.4% vs 22% in the control and exposed groups, respectively). In ROC analysis, there was no difference between the groups (AUC 90% vs 87%, p=0.56). The use of antiplatelet and anticoagulant drugs did not increase the risk of positive FIT results on multivariate logistic regression analysis. CONCLUSIONS: FIT accuracy for CRC detection remained unaffected despite more patients testing positive in the exposed group. FIT should be considered a supplementary tool for triage. Antiplatelet and anticoagulant drugs do not need to be discontinued before collection of FIT.

Development and internal validation of clinical prediction models for outcomes of complicated intra-abdominal infection.

BACKGROUND: Complicated intra-abdominal infections (cIAIs) are associated with significant morbidity and mortality. The aim of this study was to describe the clinical characteristics of patients with cIAI in a multicentre study and to develop clinical prediction models (CPMs) to help identify patients at risk of mortality or relapse. METHODS: A multicentre observational study was conducted from August 2016 to February 2017 in the UK. Adult patients diagnosed with cIAI were included. Multivariable logistic regression was performed to develop CPMs for mortality and cIAI relapse. The c-statistic was used to test model discrimination. Model calibration was tested using calibration slopes and calibration in the large (CITL). The CPMs were then presented as point scoring systems and validated further. RESULTS: Overall, 417 patients from 31 surgical centres were included in the analysis. At 90 days after diagnosis, 17.3 per cent had a cIAI relapse and the mortality rate was 11.3 per cent. Predictors in the mortality model were age, cIAI aetiology, presence of a perforated viscus and source control procedure. Predictors of cIAI relapse included the presence of collections, outcome of initial management, and duration of antibiotic treatment. The c-statistic adjusted for model optimism was 0.79 (95 per cent c.i. 0.75 to 0.87) and 0.74 (0.73 to 0.85) for mortality and cIAI relapse CPMs. Adjusted calibration slopes were 0.88 (95 per cent c.i. 0.76 to 0.90) for the mortality model and 0.91 (0.88 to 0.94) for the relapse model; CITL was -0.19 (95 per cent c.i. -0.39 to -0.12) and - 0.01 (- 0.17 to -0.03) respectively. CONCLUSION: Relapse of infection and death after complicated intra-abdominal infections are common. Clinical prediction models were developed to identify patients at increased risk of relapse or death after treatment, these now require external validation.

Accuracy of faecal immunochemical testing in patients with symptomatic colorectal cancer.

BACKGROUND: The aim of this study was to determine the diagnostic accuracy of the faecal immunochemical test (FIT) for detecting colorectal cancer in symptomatic patients. METHODS: This was a prospective study of patients with bowel symptoms. Stool samples were collected during rectal examination. The HM-JACKarc assay (Kyowa Medex, Tokyo, Japan) was used to quantify faecal haemoglobin (Hb); positive results were those with at least 10 µg Hb/g faeces. Two-by-two tables and receiver operating characteristic (ROC) curve analysis were used to determine diagnostic accuracy; χ2 and Mann-Whitney U tests were used to compare other parameters. RESULTS: A total of 928 patients were included (M : F ratio 1 : 1·5; median age 72 (i.q.r. 64-80) years). The overall prevalence of colorectal cancer was 5·1 per cent. The FIT had sensitivity of 85·1 per cent, specificity of 83·5 per cent, positive predictive value of 22·6 per cent and negative predictive value of 99·0 per cent. ROC analysis of FIT for diagnosing colorectal cancer gave an area under the curve value of 0·89 (95 per cent c.i. 0·84 to 0·94). Significant bowel pathology was detected more frequently in FIT-positive patients (35·1 per cent versus 7·1 per cent in FIT-negative patients; P < 0·001). There were sex differences in FIT positivity (23·7 per cent in men versus 17·4 per cent in women; P = 0·019); the sensitivity of FIT for colorectal cancer in women was also low. False-negative FIT results were found mainly in women referred with iron-deficiency anaemia, who were found to have caecal cancer. CONCLUSION: FIT effectively excluded colorectal cancer in symptomatic patients. Integration of FIT into the diagnostic pathway for colorectal cancer would direct resources appropriately to patients with a greater likelihood of having the disease.

ANTECEDENTES: Determinar la precisión diagnóstica de la prueba inmunoquímica fecal (faecal immunochemical test, FIT) para la detección del cáncer colorrectal (colorrectal cáncer, CRC) en pacientes sintomáticos. MÉTODOS: Se llevó a cabo un estudio prospectivo en pacientes con síntomas intestinales. Se recogieron muestras de heces durante la exploración rectal. Se utilizó el test HM-JACKarc (Kyowa-Medex, Japón) para cuantificar la hemoglobina fecal (f-Hb), en la que los resultados positivos eran valores mayores o iguales a 10 µg Hb/g de haces. Se utilizaron tablas de dos por dos y el análisis de la curva del operador del receptor (receiver operator curve, ROC) para calcular la precisión diagnóstica; las variables se compararon mediante los tests de ji-al cuadrado y U de Mann-Whitney. RESULTADOS: Se incluyeron un total de 928 pacientes (V:M = 1:1,5; mediana de edad 72 años, rango intercuartílico 64-80). La prevalencia global de CRC fue del 5%. El FIT presentó una sensibilidad del 85,1%, especificidad del 83,5%, valor predictivo positivo del 22,6% y valor predictivo negativo del 99%. El análisis de la curva ROC de FIT para el diagnóstico de CRC mostró un valor del área bajo de curva de 0,89 (i.c. del 95% 0,84-0,94, P < 0,001). En el grupo FIT-positivo, se detectaron un mayor número estadísticamente significativo de patologías intestinales (35,7% versus 7%, P < 0,001). Se observaron diferencias por sexo en la positividad de FIT (varones 23,7% versus mujeres 17,44%, P = 0,019); la sensibilidad de FIT para el diagnóstico de CRC en las mujeres también fue inferior. El grupo de falsos negativos de CRC incluía principalmente mujeres que habían sido referidas con anemia ferropénica en las que se detectaron cánceres del intestino ciego. CONCLUSIÓN: La prueba FIT fue efectiva para excluir a los pacientes sintomáticos con CRC. La integración de FIT en el procedimiento diagnóstico del CRC dirigiría apropiadamente los recursos a pacientes con una mayor probabilidad de presentar un CRC.