Association Between Body Mass Index and Functional Dyspepsia in Young Japanese People

Background/Aims Evidence regarding the association between body mass index (BMI) and functional dyspepsia (FD) in the Asian population is limited. Further, no study has evaluated this issue in young people in Asian and Western populations. Thus, we aim to investigate this issue among young Japanese people. Methods The study subjects comprised of 8923 Japanese university students. BMI was divided into 4 categories (quartiles) on the basis of the study subjects' distribution (lowest, low, moderate, and high [reference]). The definition of lean, normal, overweight, and obese was BMI < 18.5 kg/m(2), 18.5 BMI <= 25 kg/m(2) (reference), 25 kg/m(2), BMI < 30 kg/m(2), and 30 kg/m(2), <= BMI, respectively. The definition of FD was based on the Rome III criteria. Results The prevalence of FD was 1.9% in this cohort. The lowest BMI was independently associated with FD after adjustment (adjusted odds ratio [OR], 2.88; 95% confidence interval [CI], 1.46-3.67); P for trend = 0.001). The lowest BMI was independently associated with FD in women but not in men (OR, 2.94; 95% CI, 1.59-5.77; P for trend = 0.001). Leanness was independently associated with FD in total and in women but not in men (total: adjusted OR, 2.01; 95% CI, 1.40-2.86) and women (OR, 2.19; 95% CI, 1.35-3.45). However, interaction analysis showed no significant difference for sex. Conclusions Among young Japanese people, BMI may be independently inversely associated with FD. Leanness may be an independent associated factor for FD in the young Japanese women.