Cost-effectiveness analysis of a multicentre randomized clinical trial comparing surgery with conservative management for recurrent and ongoing diverticulitis (DIRECT trial)

BACKGROUND: The results of the DIRECT trial, an RCT comparing conservative management with elective sigmoid resection in patients with recurrent diverticulitis or persistent complaints, showed that elective sigmoid resection leads to higher quality of life. The aim of this study is to determine the cost-effectiveness of surgical treatment at 1- and 5-year follow-up from a societal perspective.

METHODS: Clinical effectiveness and resource use were derived from the DIRECT trial. The actual resource use and quality of life (EQ-5D-3L™ score) were documented prospectively per individual patient and analysed according to the intention-to-treat principle for up to 5 years after randomization. The main outcome was the incremental cost-effectiveness ratio (ICER), expressed as costs per quality-adjusted life-year (QALY).

RESULTS: The study included 106 patients, of whom 50 were randomized to surgery and 56 to conservative treatment. At 1- and 5-year follow-up an incremental effect (QALY difference between groups) of 0·06 and 0·43 respectively was found, and an incremental cost (cost difference between groups) of €6957 and €2674 respectively, where surgery was more expensive than conservative treatment. This resulted in an ICER of €123 365 per additional QALY at 1-year follow-up, and €6275 at 5 years. At a threshold of €20 000 per QALY, operative treatment has 0 per cent probability of being cost-effective at 1-year follow-up, but a 95 per cent probability at 5 years.

CONCLUSION: At 5-year follow-up, elective sigmoid resection in patients with recurring diverticulitis or persistent complaints was found to be cost-effective. Registration number: NTR1478 (www.trialregistrer.nl).