Prevalence of Irritable Bowel Syndrome, Functional Dyspepsia and their Overlap in Bulgaria: a Population-Based Study.

We aimed to evaluate the prevalence of irritable bowel syndrome (IBS), functional dyspepsia (FD), and their overlap syndrome (OS) in the Bulgarian population and to assess the risk factors associated with these disorders. We sent an internet-based survey to Bulgarian adults. The survey collected data on socio- demographic, behavioral and lifestyle characteristics, and diagnostic questions following the Rome IV criteria to assess IBS, FD and their overlap occurrence. Data was collected from 1,896 individuals (mean age = 35.5 years, 18-65, SD=11.7), 73.1% females. The prevalence of IBS was 20% (14% were with predominant constipation, 32% with predominant diarrhea, 52% had IBS with mixed bowel habits, and 2% unclassified IBS). Gender (p=0.005), age (p<0.001), marital status (p=0.009), occupation (p=0.001), alcohol consumption (p=0.013), sexual problems (p<0.001), FD (p<0.001), and milk intolerance (p<0.001) were significantly associated with IBS. Females (p=0.032; OR: 1.50), patients with FD (p<0.001; OR: 104.98), sexual problems (p= 0.001; ОR: 1.55 ), and milk intolerance (p<0.001; OR: 2.22) are at a higher risk of having IBS. The prevalence of FD was 12.7% (39% had postprandial distress syndrome, 33% epigastric pain syndrome, and 28% had the overlapping variant). Patients with IBS (p<0.001; OR: 127.88) and milk intolerance (p<0.001) were significantly associated with FD prevalence. The prevalence of OS was 11.7%. Gender (p=0.013), milk intolerance (p<0.001, OR: 1.65), urinary (p=0.035) and sexual problems (p<0.001, ОR: 1.80) were associated with OS prevalence. This is the first study to estimate the prevalence of IBS, FD, and their OS and assess the behavioral and demographic risk factors associated with these disorders in the Bulgarian population. Our results are valuable in filling in the epidemiological data gap regarding IBS, FD, and OS in Eastern Europe.