[Faecal occult blood test in symptomatic patients in primary care: A retrospective study in a healthcare area of Toledo]. / Sangre oculta en heces en pacientes sintomáticos en Atención Primaria: Un estudio retrospectivo en el área sanitaria de Toledo.

AIM: To review referral protocol in symptomatic patients from primary care of using 15µgHb/g faeces threshold with three consecutive samples in faecal occult blood (FOB) test. To compare test utility using current recommendations of 10µgHb/g faeces threshold and one sample. MATERIAL AND METHODS: A retrospective observational study was designed, including FOB samples of symptomatic patients from primary care. Samples were analyzed at the biochemistry laboratory in 2017. Seven hundred and fifteen patients tested positive and 925 patients negative. Exclusion criteria were secondary care request and patients under the age of 18. Descriptive analysis was performed of FOB results and clinical data about request and colonoscopy. FOB test's diagnostic utility was studied for different threshold (10 and 15µgHb/g faeces) in the same population. RESULTS: FOB positivity rate was 22.8% and cancer detection rate was 11%. However, the number of samples does not modify diagnostic precision. Negative predictive value is higher with 10µgHb/g faeces threshold. CONCLUSIONS: Correct patient selection and optimal threshold increase cancer detection rate. The protocol with 10µgHb/g faeces threshold and one sample collection for symptomatic patients from primary care improves the FOB test's purpose.