Relationships between body mass index and constipation, gastroesophageal reflux disease, stool forms based on the Bristol Stool Form Scale, and education level: results from an internet survey in Japan

Detailed evaluations of body mass index (BMI) and stool form based on the Bristol Stool Form Scale (BSFS) in individuals with ‍constipation, gastroesophageal reflux disease (GERD), and concomitant constipation and GERD have not been performed in Japan. This study was an internet survey conducted to examine the relationships between BMI and constipation, GERD, stool forms based on the BSFS, and education level. This internet-based survey recruited participants from general public survey panels. 10,000 individuals meeting the eligibility criteria were enrolled. Questions included demographics, medical data, and assessments based on validated measures for constipation and GERD. BMI was significantly lower in males with versus without constipation. BMI was significantly higher with GERD both males and females. Mean BMI increased from the BSFS-1/2 group through the BSFS-3/4/5 to the BSFS-6/7 groups in both sexes. BMI was highest in individuals with a maximum education level of junior high school and second highest in individuals completing high school. This is the first real-world survey that closely examines the relationship between BMI and stool forms of individuals in Japan. When the BMI increased, stool forms varied from hard to watery in Japanese people. BMI was related with education level in Japan. (Trial registration: UMIN000039688)