Lactase deficiency has a high prevalence worldwide. Thus, a valid symptom scale would be a useful tool for identifying patients with lactose malabsorption. Objective To develop, validate, and apply a symptoms questionnaire on lactose malabsorption to identify lactose malabsorbers diagnosed with the gold-standard hydrogen breath test. Methods In the first part of the study, 292 patients completed a questionnaire at the end of a 50-g lactose breath test. The questionnaire included five items (diarrhea, abdominal cramping, vomiting, audible bowel sounds, and flatulence or gas) scored on a 10-cm visual analogue scale. In the second part of the study, 171 patients completed the questionnaire twice: first, according to their opinion when consuming dairy products at home and second, after a 50-g lactose breath test. Patients were grouped as absorbers or malabsorbers according to the result of the breath test. Results Diarrhea, abdominal cramping, and flatulence were scored significantly higher in malabsorbers than in absorbers. Total score of the symptomatic questionnaire was significantly higher in malabsorbers (17.5 versus 3.0, P < 0.01). According to receiver operator characteristics (ROC) analysis, the most discriminant cut-off of the total score to identify lactose malabsorption was 6.5 (sensitivity 0.75, specificity 0.67). In 58 malabsorbers the effect size of the questionnaire to determine sensitivity to change was 1.32. In the second part of the study, scoring of the home questionnaire was higher than after the lactose-breath test. The lactose malabsorbers rate was higher according to the home questionnaire than after the lactose breath test (72% versus 52%). The home questionnaire had excellent sensitivity (0.82) but low specificity (0.35). Conclusion We developed and validated a five-item symptoms questionnaire for lactose malabsorption. This is a valid test that permits patients with a total score lower than 7 to be excluded from future studies.
Hydrogen breath test Lactose breath test Lactose intolerance Lactose malabsorption Symptoms score
This is a preview of subscription content, log in to check access.
We thank Miss. Christine O’Hara for valuable contributions to the English revision of this manuscript. Ciberehd is funded by the Instituto de Salud Carlos III, Spain. This work was supported in part by grants from the Generalitat de Catalunya (RE: 2001SGR00389) and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd, Spain).
Peña A, Peña JF. Malabsorción de lactosa en estudiantes españoles. Tolerancia intestinal a la sobrecarga oral de lactosa. Rev Esp Enferm Dig. 1971;35:925–938.Google Scholar
Carnicer J. Malabsorció de lactosa en una població preescolar i escolar. But Soc Cat Pediatr. 1993;53:26–32.Google Scholar
Vázquez C. Malabsorción de los hidratos de carbono en el niño: malabsorción de la lactosa. Esp Ped. 1975;8:166–178.Google Scholar
Suarez FL, Savaiano DA. Lactose digestion and tolerance in adult and elderly Asian-Americans. Am J Clin Nutr. 1994;59:1021–1024.PubMedGoogle Scholar
Hermans MM, Brummer RJ, Ruijgers AM, Stocbrügger RW. The relationship between lactose tolerance test results and symptoms of lactose intolerance. Am J Gastroenterol. 1997;92:981–984.PubMedGoogle Scholar
Casado A, Prieto L, Alonso J. El tamaño del efecto de la diferencia entre dos medias: ¿estadísticamente significativo o clínicamente relevante? Med Clin (Barc). 1999;112:584–588.Google Scholar
Bullinger M, Anderson R, Cella D, Aaronson N. Developing and evaluating cross-cultural instruments from minimum requirements to optimal models. Qual Life Res. 1994;2:451–459. doi:10.1007/BF00422219.CrossRefGoogle Scholar