Seasonal variations in peptic ulcer disease incidence in Taiwan, a country spanning both tropical and subtropical regions: a real-world database analysis.

Objective: Previous studies have shown that the incidence of peptic ulcer disease (PUD) exhibits seasonal variations. This study aimed to investigate the seasonal variation in PUD incidence in Taiwan, which spans both tropical and subtropical regions, using a nationwide database.

Methods: A cross-sectional study was conducted using real-world claims data from Taiwan, which includes a representative sample of 2 million individuals. Patients hospitalised with a primary diagnosis of PUD between 2001 and 2019 were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes for gastric ulcers (GUs), duodenal ulcers (DUs) and unspecified peptic ulcers. Descriptive statistics were used to present the seasonal variations in PUD incidence. Patients' gender, age, PUD type, geographical region and non-steroidal anti-inflammatory drugs (NSAIDs) usage across the four seasons (spring, summer, fall, winter) were compared using Pearson's χ² test.

Results: Among the 13 022 patients, new-onset PUD cases varied annually, peaking at 771 cases in 2004 and reaching a low of 614 cases in 2018. PUD incidence was higher in males than in females, and more common in elderly individuals aged ≥65 (59.5%). GU had the highest prevalence (56.1%), followed by DU (36.3%) and unspecified ulcers (7.7%). PUD incidence peaked in winter (26.8%), followed by spring (25.1%), fall (24.2%) and summer (23.9%). This seasonal trend was consistent across gender and age groups, with no significant impact on latitude, NSAID usage or PUD type.

Conclusion: Across the tropical and subtropical regions of Taiwan, seasonal variation in PUD incidence is observed with the highest rates occurring in winter, regardless of age or sex. However, NSAID usage tends to obscure this trend. The seasonal variation in DU incidence showed no significant differences between north and south Taiwan, suggesting that factors other than temperature may affect DU incidence compared with their effect on GU incidence.