Gastrointestinal symptoms and bowel habits in 53 046 healthy Danish blood donors: a nationwide cross-sectional study.

OBJECTIVE

To characterise gastrointestinal symptoms and bowel habits in healthy blood donors and explore symptom phenotypes and their associated factors.

METHODS

Between November 2020 and March 2023, 53 046 participants in the nationwide Danish Blood Donor Study completed a questionnaire including 13 gastrointestinal symptoms, defaecation pattern regularity, stool frequency, and stool consistency. We used a data-driven approach to explore symptom phenotypes and investigated associated factors by multinomial logistic regression.

RESULTS

Among the 53 046 participants (52% women), 68% (95% CI 67.5% to 68.3%) reported at least one of 13 gastrointestinal symptoms. The most frequent symptoms were bloating (40%), abdominal rumbling (40%), abdominal pain (17%), acid regurgitation (13%), heartburn (12%), diarrhoea (12%), nausea (12%), and constipation (10%). Half of the participants (50%) had a regular defaecation pattern (defined as generally the same stool consistency and stool frequency) consisting of Bristol Stool Form Scale 4 stools 1-3 times per day. Symptom phenotypes and their prevalence among 51 820 near-complete case participants were as follows: (1) no gastrointestinal symptoms (32%); (2) bloating and/or rumbling only (21%); (3) acid regurgitation and/or heartburn only (4%); (4) any other one or two symptoms (14%); (5) any three or four symptoms (18%); (6) any five or six symptoms (7%); (7) at least seven symptoms (3%). The acid regurgitation and/or heartburn only phenotype associated with obesity, and the remaining symptomatic phenotypes were associated with female sex, decreasing age, and an irregular defaecation pattern, even after excluding individuals with self-reported irritable bowel syndrome, lactose intolerance, or gluten intolerance.

CONCLUSION

Most healthy adults, especially women younger than 50 years, experience gastrointestinal symptoms. Symptom phenotypes strongly correlate with sex, age, and bowel habits.