Among total number of 26 163 individuals attending Pomeranian Medical University Endoscopic Centre in 2021–2023, there were 15 698 potentially eligible patients, 6279 examined for eligibility, 3767 confirmed eligible, 2150 included in the study, and 2070 completing follow-up and analysed. The primary reason for not including patients after being confirmed eligible was not enough personnel to collect data for the present study in the Clinic.
The mean age of participants was 57.5 ± 15.1 years, with 58.2% (N = 1204) being females. The mean body mass index (BMI) was 27.1 ± 6.3 kg/m2. Among the participants, 427 (20.6%) reported previous COVID-19 infection. The common comorbidities such as hypertension and diabetes mellitus were present in 35.1% (N = 726) and 13.0% (N = 270), respectively.
Using the Rome IV Criteria, 436 (21%) subjects met the criteria for a diagnosis of IBS, while functional dyspepsia (FD) was identified in 248 (12%) participants. Considering the overlap between the two conditions, 310 (15.0%) subjects had IBS, 122 (5.9%) had FD, and 126 (6.1%) met the criteria for both IBS and FD based on the questionnaires (Fig. 1A). Since the criteria for FD require the absence of organic, metabolic, and systemic changes that could likely cause symptoms, we re-evaluated the diagnoses using GI endoscopic findings, which were identified as gastric or duodenal mucosal abnormalities, including gastric and/or duodenal erosions and ulcers, along with the presence of Helicobacter pylori infection in some subjects. After this re-evaluation, 90 (4.35%) subjects met the criteria for FD, resulting in 94 (4.54%) subjects with overlapping IBS and FD (Fig. 1B).
Figure 1.
Figure 2 illustrates the prevalence of IBS, FD, and overlapping IBS/FD diagnoses among males and females. The bar plots demonstrate that both conditions and their overlap exhibit distinct patterns based on sex. Notably, the data reveals that females are more likely to be diagnosed with IBS and FD compared to males in both questionnaire-based (Fig. 2A, Chi-square = 29.03, P < 0.0001) and gastroscopic-based revised diagnoses (Fig. 2B, Chi-square = 21.06, P < 0.001). This sex-specific prevalence suggests potential underlying biological, hormonal, or psychosocial factors that may contribute to these differences.
Figure 2.
The odds ratio (OR) for being diagnosed with IBS was calculated to assess the likelihood of females being diagnosed with IBS compared to males. For the non-revised diagnoses, the analysis revealed an OR of 1.636 (95% CI: 1.266–2.12, P < 0.001). This indicates that females have a significantly higher likelihood of being diagnosed with IBS compared to males, with an estimated 63.6% increased odds. Similarly, for the revised diagnoses, the OR was 1.60 (95% CI: 1.24–2.06, P < 0.001). For FD, the OR for the non-revised diagnoses was 1.46 (95% CI: 0.99–2.15, P = 0.058), indicating a non-significant trend towards higher odds in females. However, the revised diagnoses showed a statistically significant OR of 1.61 (95% CI: 1.03–2.52, P = 0.038), suggesting that females have a 61% higher likelihood of being diagnosed with FD compared to males after revision. Regarding the overlap group (IBS + FD), the non-revised diagnoses showed an OR of 2.24 (95% CI: 1.49–3.36, P < 0.0001), indicating that females have more than twice the odds of being diagnosed with both conditions compared to males. The revised diagnoses presented an OR of 1.80 (95% CI: 1.15–2.83, P = 0.009), confirming that females still have significantly higher odds of overlapping diagnoses of IBS and FD. The process of revising the FD diagnoses appears to have a notable impact on the strength and significance of the observed associations. While the non-revised data already indicates significant sex differences, the revised data often shows a slight reduction in the odds ratios but enhances statistical significance, particularly for FD.
Figure 3.
Proportion of patients referred for GI endoscopic examination based on indication differed significantly in both without (P < 0.0001, Fig. 3A) and with gastroscopic evaluation (P < 0.0001, Fig. 3B).
In patients with IBS changes in bowel movements were as follows: diarrhoea (N = 109), constipation (N = 117) or both (N = 73) and reported by 68.6% (N = 299) of respondents, Fig. 4A). Among individuals with FD, the predominant symptoms included upper abdominal pain (63.3% of respondents, N = 157) and a feeling of fullness or early satiety after meals (36.7%, N = 91), Fig. 4B.
Figure 4.
Analysis of stool types among IBS patients showed that 25% suffered from diarrhea, 26.8% from constipation and 31.4% had stools of normal consistency. Among those with dyspepsia, abdominal pain was the main symptom, reported by 63.3% of patients.
Impact of COVID-19
Our statistical analysis revealed that individuals with a history of COVID-19 infection had a higher risk of developing IBS compared to those without such a history, although this result was only borderline significant (OR = 1.47, 95% CI 1.01–2.15, P = 0.050). In contrast, the odds ratio (OR) for developing FD among those with a history of COVID-19 infection was 1.22 (95% CI 0.59–2.52, P = 0.562), indicating no significant association.
Gastrointestinal endoscopic findings among patients with IBS and FD
The analysis of colonoscopy findings (Fig. 5) revealed significant differences in the odds of detecting polyps and inflammation among the different groups (P = 0.0007 and P = 0.012, respectively). When evaluating the presence of polyps (Fig. 5A), the odds ratio (OR) for the FD group compared to the reference group (Other) was 0.21 (95%CI 0.08–0.55, P = 0.0002), indicating a significantly lower likelihood of finding polyps in the FD group. In contrast, the IBS group showed an OR of 0.67 (95%CI 0.47–0.96, P = 0.030), suggesting a moderately reduced odds of polyp detection compared to the reference group. The combined IBS and FD group had an OR of 0.69 (95%CI 0.38–1.27, P = 0.305), which was not statistically significant, indicating no substantial difference from the reference group in terms of polyp detection.
Figure 5.
For inflammation findings during colonoscopy (Fig. 5C), the FD group had an OR of 0.36 (95%CI 0.05–2.68, P = 0.509), showing no significant difference from the reference group. However, the IBS group exhibited significantly higher odds of detecting inflammation, with an OR of 2.12 (95%CI 1.23–3.65, P = 0.012). The combined IBS and FD group also demonstrated increased odds of inflammation with an OR of 2.08 (95% CI 0.85, 5.09, P = 0.128), although this result was not statistically significant.
Figure 6.
The gastroduodenoscopy examination results demonstrated varying odds of detecting specific conditions across different patient groups (Fig. 6). For GERD (Fig. 6A), the odds ratio (OR) compared to the reference group (Other) was 0.95 (95%CI 0.48–1.87, P = 1.0), indicating no significant difference in the likelihood of finding GERD between the groups. In contrast, the odds of identifying gastro-duodenal pathology were significantly lower in the group under examination, with an OR of 0.25 (95%CI 0.11–0.55, P < 0.0001), suggesting a markedly reduced likelihood of this condition compared to the reference group. For Ulcer Disease, the OR was 1.61 (95% CI 0.45–5.68, P = 0.442), showing no statistically significant difference from the reference group, implying that the odds of detecting ulcers were similar across the groups. Lastly, the detection of Hiatal Hernia had an OR of 1.34 (95% CI 0.50–3.57, P = 0.579), also indicating no significant difference in the likelihood of finding hernias between the examined group and the reference group.
The association between the BMI and the probability of diagnoses was analysed using a generalized linear model with BMI and sex as independent variables and their interaction. We found no significant association for BMI. Predictor effect plots illustrating the relationship between BMI and the probability of diagnoses, as well as the interaction effect between BMI and sex, are shown in Fig. 7.
Figure 7.
In our study, we reported that after a 12 months follow-up period, out of 554 follow-up responses of subjects initially fulfilling the IV criteria of IBS or FD diagnoses − 248 (49.6%) responders fulfilled the criteria for FD and 435 (45.5%) for IBS.