Concerns around the extensive use of mesalazine for ulcerative colitis and continuous treatment with biologics for Crohn’s disease have been referred to the next meeting of PBAC.

A Drug Utilisation Sub-Committee (DUSC) charged with investigating the cost-effectiveness of medicines used in IBD found mesalazine was the most commonly prescribed medicine and its use was increasing.

In particular, there was concern that ‘extensive use of mesalazine in place of sulfasalazine, and the possible use of higher doses, may not reflect cost- effective use’.

PBS data showed that at least half of all patients who initiated treatment for ulcerative colitis in 2015 initiated on mesalazine, the report said.

This is despite PBS restrictions requiring the patient have a documented hypersensitivity reaction to a sulphonamide or intolerance to sulfasalazine.

DUSC acknowledge that mesalazine may be used in preference to sulfasalazine because it is better tolerated, requires less intensive monitoring and has a lower pill burden.

“In addition, sulfasalazine reduces sperm count and the peak age for onset of inflammatory bowel disease coincides with peak reproductive years,”the report said.

It said increasing number of prescriptions for mesalazine may be due to dose escalation and requested further analysis to examine this.

DUSC also found the proportion of patients continuing on biologic therapy for Crohn’s indications was substantially higher than anticipated.

“The number of patients treated with biologics for severe refractory adult Crohn’s disease, fistulising Crohn’s disease and moderate to severe refractory Crohn’s disease in children and adolescents had increased steadily from 2007 to 2016.”

About 60% of adult patients with severe refractory Crohn’s disease initiating on biologic therapy in 2011, remained on treatment after five years.

DUSC noted this was much higher than the continuation rates in the clinical trials, which may be due in part to patients switching to a second (or third) agent.

They added that ‘continuation rates in fistulising Crohn’s disease seem high’ and ‘patients may not be ceasing treatment after fistula closure’.

In 2016, 7,505 patients received a biologic for severe adult refractory Crohn’s disease, 2,135 for fistulising Crohn’s disease and 824 patients received treatment for paediatric Crohn’s disease.

DUSC acknowledged that the restrictions do not include rules or advice of when patients should stop or restart treatment.