Economic burden of diverticular disease: An observational analysis based on real world data from an Italian region

Diverticular disease (DD), a herniation of the colonic mucosa through the muscle layer, covers a wide variety of conditions associated with the presence of diverticula in the colon. The most serious form is an acute episode of diverticulitis, which can lead to hospitalization and surgery with various types of consequences. The main aim of this study is to evaluate the economic burden of hospitalizations arising from acute episodes of diverticulitis using data from the administrative databases used in the Marche region in Italy and, as a secondary objective of this real-world data analysis, to study patient outcome variables following initial hospitalization for diverticulitis.

A deterministic linkage was performed at individual user level between the different administrative sources of the Marche region through anonymous ID number for a period of analysis between 1 January, 2008 and 31 December, 2014. We enrolled all patients with at least one hospitalization for "diverticulitis of the colon without mention of haemorrhage" (ICD-9-CM code 562.11) or "diverticulitis of the colon with haemorrhage" (ICD-9-CM code 562.13) as primary or secondary diagnosis. For each patient we assessed the cost of hospitalization, of medicines and of specialist services considering a time-scale of one year or cohort analysis 365days after first admission.

The total number of residents in the Marche region who had at least one hospitalization for diverticulitis in the period 2008-2014 was 2987 (427 patients a year, corresponding to about 35 patients per 100,000 adult residents); the total number of admissions was 3453 (just over 490 a year). The direct healthcare costs incurred by the Marche region for episodes of diverticulitis in 2008-2014 amounted to approximately €11.4 million (€1.6 million a year), of which €10.9 million (95.5%) for the hospitalizations, € 246,000 (2.1%) for pharmaceutical treatment and €270,000 (2.4%) for specialist outpatient services. The average annual cost per patient was €3826, of which €3653 was for hospitalization, while pharmaceutical expenditure and specialist services accounted for €83 and €90, respectively. The cohort of patients undergoing a first admission for diverticulitis between 2010 and 2013 was made up of 1729 people (54.4% women, mean age 68.9 years), of whom 1500 (86.8%) did not undergo surgery while in hospital. Hospital mortality, recorded only for the over-65 age class, averaged 1.2%; for patients not receiving surgery during the initial hospitalization it was 0.5%, reaching 5.2% in patients undergoing surgery. The percentage of patients with one or more readmissions for diverticulitis within a year of the first was on average 7.8% and in 48% of cases this resulted in surgery.

Our study is the first analysis in Italy to use real-world data to measure the financial impact of diverticular disease. Assuming that the diagnostic and therapeutic behaviour identified in the Marche region could be representative of the situation nationwide, the estimated annual number of hospitalizations in Italy for acute episodes of diverticulitis is 19,000. The total amount of economic resources needed to treat patients suffering from acute episodes of diverticulitis is estimated at €63.5 million a year.