Trends in primary care and hospital admission episodes for infectious intestinal disease in North-West London, 2015-2024

Background Infectious intestinal disease (IID) incurs substantial healthcare demands. The relationship between primary and secondary care utilisation for IID remains underexplored.

Aim To assess patient characteristics and time trends in IID-related primary care and hospital admission episodes.

Design & Setting A population-based, linked data study using deidentified healthcare and sociodemographic data from the Discover-NOW database of 2.7 million people in North-West London between 2015-2024.

Method IID-related episodes in primary care and hospital settings were defined using SNOMED CT and ICD10 codes. Annual episode frequencies were described. Multivariable logistic regression estimated odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations of patient characteristics with 1) hospital admission during a primary care episode, and 2) primary care activity coinciding with or preceding a hospital admission episode.

Results Between 2015-2024, annual IID-related primary care episodes decreased from 51 009 to 40,450, while hospital admission episodes increased from 8732 to 10 356. Children aged 0-4 years accounted for 23.7% of primary care and 7.8% of hospital admission episodes, compared to 16.1% and 42.7% respectively for adults aged≥60 years. During primary care episodes, compared to adults aged 18-34 years, the 0-4 years (OR 1.30, 95% CI 1.19-1.42) and≥80 years (4.77, 4.36-5.22) age groups had a higher odds of hospital admission. For hospital admission episodes, younger age and lower socioeconomic deprivation were associated with coinciding or previous primary care activity.

Conclusion IID-related primary care activity has declined since 2015 whilst hospital admissions have increased. Young children and older adults are more likely to be admitted to hospital during an IID-related primary care episode.