Objective:

To estimate ulcerative colitis (UC) and Crohn’s disease (CD) prevalence and incidence in Italy and describe treatment, adherence, and direct healthcare expenditures among patients with UC newly initiating mesalazine.

Approach:

• Design and data: Retrospective observational study using linked Italian healthcare administrative records from January 2009 to May 2024.
• Population and coverage: Records came from six Local Health Units across northern, central, and southern Italy, covering approximately 4 million residents. UC and CD were identified using disease-specific hospital diagnosis or exemption codes.
• Assessments: The study examined national disease estimates and, among mesalazine-naive patients with UC, demographics, comorbidities, treatment patterns, adherence, and direct SSN healthcare expenditures.

Key Findings:

• The investigation reports contemporary Italian estimates of UC and CD prevalence and incidence; numerical estimates are not provided in the supplied context.
• Patients with UC who initiated mesalazine had suboptimal treatment adherence during follow-up.
• Healthcare expenditures remained substantial, with hospitalizations accounting for a large share.

Interpretation:

The study describes the epidemiological, treatment, and economic burden of IBD in routine Italian healthcare settings, including adherence among patients newly starting mesalazine for UC.

Limitations:

• The supplied context does not provide numerical results for prevalence, incidence, adherence, or costs.
• The analysis used administrative records from six Local Health Units rather than data from every Italian region.
• Administrative records capture reimbursed healthcare utilization and services.

Conclusion:

The authors report a considerable clinical-practice burden associated with IBD in Italy, suboptimal mesalazine adherence among patients with UC, and substantial healthcare expenditures largely attributable to hospitalizations.