Background and importance Causing excess mortality and prolonged hospitalisations, mediastinitis is a serious sternal wound infection that can occur after open heart surgery. With an incidence of 4.2% in 2020 in our hospital which specialises in thoracic and cardiovascular surgery, its occurrence must be prevented.

Aim and objectives To compare the cost-effectiveness of standard treatment with Collatamp G, a gentamicin-impregnated implant, and negative pressure therapy with Pico 7.

Material and methods Cost-effectiveness study comparing one retrospective control arm (standard sternal dressing – July to September 2019) and two prospective intervention arms (Collatamp G and Pico 7 – November 2020 to February 2021). Patients with at least one risk factor (RF) for postoperative mediastinitis were included. The primary endpoint was the incidence of mediastinitis at 1 month after surgery (M1). From the medical record, postoperative hospital costs were collected to calculate the incremental cost-effectiveness ratios (ICER).

Results A total of 82 patients were included. The mean number of RF/patient was 1.7 (83/48) in the control arm, 1.8 (46/25) in the Collatamp G arm and 2.4 (22/9) in the Pico 7 arm (p<0.05). The incidence of mediastinitis at M1 was 8% (4/48), 4% (1/25) and 11% (1/9), respectively (p>0.05). Two cases of air leak making the Pico 7 system ineffective were noted. The postoperative hospital costs were €12 860/patient (control), €10 451/patient (Collatamp G) and €13 127/patient (Pico 7). The ICER is €55 583/mediastinitis avoided with Collatamp G versus €9616/mediastinitis avoided with Pico 7.

Conclusion and relevance The difference in the incidence of mediastinitis was not significant. Both strategies are more cost effective than standard sternal dressing. The ICER is in favour of Collatamp G, but the Pico 7 arm population has more RF and the observed leaks can be resolved. Pico 7 should be re-evaluated with the addition of a sealing patch when there is a risk of leakage. By supporting surgical teams in the evaluation of preventive strategies, the hospital pharmacist contributes to optimise treatments at the best cost.

References and/or acknowledgements 1. Kowalewski M, Pawliszak W, Zaborowska ME, et al. Gentamicin-collagen sponge reduces the risk of sternal wound infections following heart surgery. Meta-analysis. J Thorac Cardiovasc Surg 2015;149:1631–40.

2. Hyldig N, Birke-Sorensen H, Kruse M, et al. Meta-analysis of negative-pressure wound therapy for closed surgical incisions. BJS 2016;103:477–86.

Conflict of interest No conflict of interest