Incidence and predictive factors for positive 75SeHCAT test: improving the diagnosis of bile acid diarrhoea

Abstract

Aims: To determine the value of 75SeHCAT retention in determining bile acid diarrhoea (BAD), treatment response and predictors of a positive result.Methods: Retrospective casenote review of consecutive patients undergoing 75SeHCAT from 2008 to 2014, including gender, age, history, clinical, and laboratory parameters. This included diseases associated with Type 1 BAD (ileal resection, Crohn’s disease) and Type 3 BAD. Chi-squared test and logistic regression determined factors predictive of BAD. Subjective response to treatment with bile acid sequestrants (BAS) was analysed with respect to the 75SeHCAT result.Results: Of 387 patients, 154 (39.7%) were male and average age was 50 years. Ninety-five patients (24.5%) were investigated for Type 1 BAD, 86 (22.2%) for Type 3, and 206 patients (53.2%) for Type 2 or idiopathic BAD. There was a large increase in the number performed with time but no difference in percentage positive tests. One hundred and seventy-nine patients (46.2%) had BAD. Positive result was commonest in possible Type 1 and they had most severe BAD. Ninety-nine patients had severe BAD (<5% 75SeHCAT retention), 47 moderate BAD (5% to <10% retention), and 33 mild BAD (10% to <15% retention). Predictors of a positive 75SeHCAT were right hemicolectomy (OR 4.88), cholecystectomy (OR 2.44), and Crohn’s (OR 1.86). A positive 75SeHCAT predicted a good or partial response to BAS of 66.7% (mild), 78.6% (moderate), or 75.9% (severe BAD).Conclusion: 75SeHCAT test use increased in 2008–2014, with high positive results throughout. Ileal resection, Crohn’s, and cholecystectomy independently predict BAD. 75SeHCAT predicted response to BAS.