Seasonal clustering in inflammatory bowel disease: a single centre experience

Abstract

Backgrounds and aims: External stimuli are considered as possible triggers for the onset of inflammatory bowel disease (IBD), and particularly chronic ulcerative colitis (CUC) in genetically susceptible individuals. Our aims were to investigate monthly clustering-patterns in the onset of symptoms and diagnosis of IBD, as well as health seeking behavior in those individuals. Materials and methods: Two hundred and eighty-two consecutive patients with IBD were included. Onset of symptoms (month) and delay to diagnosis were analyzed. Kruskal–Wallis and Roger’s test were used to analyze for statistical patterns in seasonal clustering. Results: There were 181 males and 101 females with IBD; mean age: 40 ± 14.7 years (median: 38, range: 14–79 years). The peak number of IBD cases was seen in winter/early spring, with the lowest numbers in autumn, which reached statistical significance in the CUC group (p: 0.029). Seasonal changes were not significantly affected by gender. The time delay to diagnosis from symptom onset was 3.0 ± 2.3 months in males (median: 2, range: 0–12 months) vs 3.2 ± 3.2 months (median: 2, range: 0–18 months) in females (not statistically significant). Conclusion: Our results show a seasonal relation in IBD cases, particularly in CUC, which may suggest external stimuli acting as a precipitant to IBD in susceptible individuals. There was a delay between symptom onset and CUC diagnosis, which was not felt to be clinically significant.

Keywords:

• chronic ulcerative colitis
• delayed diagnosis
• inflammatory bowel diseases
• seasonal variation

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Writing assistance by Turkiye Yuksek Ihtisas Hospital was utilized in the production of this manuscript.

Key issues

• External stimuli have been considered as triggers to the onset of chronic ulcerative colitis (CUC) in genetically susceptible individuals.

• Seasonal clustering in CUC does make sense and is timely and necessary to investigate.

• The relation between flare of CUC and monthly clustering has been previously reported, in Western countries and the results are not in harmony.

• There is a belief that the risk factors of CUC in the East differ from the West. Turkey is unique country lying 97% within Asia, whilst also sharing a border with Europe (3%).

• In this study, we evaluated seasonal clustering in newly diagnosed CUC patients with complaints.

• While our results are not supportive of a relation between enteric infections and CUC, upper respiratory tract infections and anti-flu drugs may be linked with the onset of CUC.

• Fluctuations of vitamin D and immune functions during the sunny and non-sunny seasons may explain the seasonal variations in the onset of CUC.

• There was no relation between seasonal clustering, CUC and gender.

• Delayed diagnosis has been investigated for the first time by our study group and there was a delay.

Notes