Trends in Incidence and Prevalence of Inflammatory Bowel Disease in Spain: A Nationwide Population-Based Study...

Long-term epidemiologic data on inflammatory bowel disease (IBD) in Spain are limited. We aimed to describe population-based temporal trends and forecast their future.

Population-based study using the Spanish Primary Care Clinical Database (BDCAP) from 2011-2024. Cases were identified using International Classification of Primary Care, second edition (ICPC-2) coding. Annual incidence and prevalence rates per 100,000 persons were obtained. Average annual percentage changes (AAPC) with associated 95% confidence intervals (CI), were calculated using log-linear regression . Forecasting was performed using autoregressive integrated moving average. Incidence was forecasted to 2029 and prevalence to 2034 with 95% prediction intervals (PIs).

Between 2011-2024, incidence remained stable, averaging around 40 per 100,000 persons annually, with no significant variations (AAPC: -0.9%; 95%CI: -2.9, 1.1). Prevalence increased from 244 to 587 cases per 100,000 persons (AAPC: 6.7%; 95%CI: 6.0, 7.5). Prevalence increased across all age groups, peaking at approximately 900 per 100,000 inhabitants among those aged 60-74 years in 2024. Substantial geographic variability was observed across regions (p<0.001). Forecasting analyses predicted stable incidence rates (AAPC: 0.0% 95%PI: 0.0%, 0.0%), while prevalence is predicted to rise continuously, reaching approximately 850 cases per 100,000 persons by 2034 (95%PI: 777.9, 923.8), with an estimated AAPC of 3.7% (95%PI: 3.57, 3.81).

IBD in Spain is characterized by stable incidence and rapidly increasing prevalence, consistent with epidemiologic stage 3 (compounding prevalence). The growing and aging IBD population indicates an increasing healthcare burden, emphasizing the need for long-term healthcare planning and resource allocation.