A semi-Markov model comparing the lifetime cost-effectiveness of mesh prophylaxis to prevent parastomal hernia in patients undergoing end colostomy creation for rectal cancer

Aim: Parastomal hernia (PSH) is a common problem following colostomy. Using prophylactic mesh during end colostomy creation may reduce PSH incidence, but concerns exist regarding the optimal type of mesh, potential long-term complications, and cost-effectiveness of its use. We evaluated the cost-effectiveness of mesh prophylaxis to prevent PSH in patients undergoing end colostomy creation for rectal cancer.

Methods: We developed a decision-analytical model, stratified by rectal cancer stages I–IV, to estimate the lifetime costs, quality-adjusted life-years (QALYs) and net monetary benefits (NMBs) of synthetic, biologic and no mesh from a UK NHS perspective. We pooled the mesh-related relative risks of PSH from 13 randomised controlled trials (RCTs) and superimposed these on the baseline (no mesh) risk from a population-based cohort. Uncertainty was assessed in sensitivity analyses.

Results: Synthetic mesh was less costly and more effective than biologic and no mesh to prevent PSH for all rectal cancer stages. At the willingness-to- pay threshold of £20,000/QALY, the incremental NMBs (95% CI) ranged between £1,706 (£1,692 to £1,720) (stage I) and £684 (£678 to £690) (stage IV) for synthetic versus no mesh, and £2,038 (£1,997 to £2,079) (stage I) and £1,671 (£1,653 to £1,689) (stage IV) for synthetic versus biologic mesh. Synthetic mesh was more cost-effective than no mesh unless the relative risk of PSH was ≥0.95 for stages I–III and ≥0.93 for stage IV.

Conclusions: Synthetic mesh was the most cost-effective strategy to prevent the formation of PSH in patients after end colostomy for any rectal cancer stage; however, conclusions are dependent on which subset of RCTs are considered to provide the most robust evidence.