Lactose malabsorption: Clinical or breath test diagnosis?

SummaryBackground & aimsLactose malabsorption (LM) is a frequent condition in adults and is often associated with bowel symptoms. Although the diagnostic gold standard is represented by assessment of the tissue lactase activity, LM diagnosis is currently made non-invasively by hydrogen breath test. Alternatively, an accurate clinical and anamnestic evaluation of symptoms can suggest LM in many cases. The aim of the study was to evaluate the diagnostic accuracy of clinical variables for the diagnosis of LM when compared to the hydrogen breath test.MethodsForty consecutive patients with suspected LM performed a hydrogen breath test after oral load of lactose (25 g). Patients were requested to answer five questions on a visual-analogical scale (0–4): subjective correlation milk/symptoms; abdominal pain; bloating; soft stools; response after milk exclusion. Statistical analysis was performed by using the Mann–Whitney U-test and Cohen's k of agreement. Also, a ROC curve was constructed to identify the best diagnostic cut-off for the resulting clinical-anamnestic score.ResultsBreath test was positive in 16 out of 40 patients (40%). The mean clinical score was significantly higher in patients with LM (14 vs 8.5; p < 0.001). On ROC curve a clinical score >10 showed a sensitivity of 91%, a specificity of 95%, positive and negative predictive values of 91% and of 95% for LM diagnosis. Additionally, a score >10 presented high concordance with the result of the breath test (k = 0.92).ConclusionsAccurate evaluation of five clinical-anamnestic variables, with the use of a simple scoring system, is almost equivalent to the hydrogen breath test for the diagnosis of lactose malabsorption and could avoid breath testing in many cases.