Multicentre non-inferiority cluster randomised trial testing Disposable versus Reusable drApes and Gowns for green OperatiNg theatres. A pragmatic 1:1 international multi-centre non-inferiority cluster randomised controlled trial, with an internal pilot. Clusters are individual hospitals.

Background: The World Health Organisation makes no recommendation for the use of disposable or reusable surgical drapes and gowns due to a lack of effectiveness evidence. Since disposable versions are likely to have higher financial and carbon costs, they are only justifiable if they can be proven to significantly reduce surgical site infections (SSIs).

Aim: This randomised controlled trial will assess whether reusable surgical drapes and gowns are non-inferior in reducing SSI compared to disposable drapes and gowns in patients undergoing surgery.

Design: Pragmatic 1:1 international multi-centre non-inferiority cluster randomised controlled trial, with an internal pilot. Clusters are individual hospitals.

Intervention: Reusable surgical drapes and gowns.

Comparator: Disposable (single-use) surgical drapes and gowns.

Sample size: The control group SSI event rate is estimated to be 12.5% based on previous literature. To determine whether reusable drapes and gowns are non-inferior to disposable drapes and gowns with a non-inferiority margin of 2.5% would require a total of 26,800 participants from 134 clusters, with an average of 200 participants per cluster, assuming 90% power, 2.5% one-sided alpha, intraclass correlation of 0.01 and 5% participant loss to follow up.

Inclusion criteria:

• Patients with at least one incision that is ≥5cm in adults and ≥3cm in children aged under 16 years. This can include both open and minimally-invasive surgery providing at least one incision meets this criteria.
• Patients with a clean-contaminated, contaminated, or dirty surgical wound. Definitions of contamination are given in Table 2.
• Patients undergoing emergency (surgery on an unplanned admission) or elective (surgery on a planned admission) surgery.
• Any operative indication (including caesarean section).
• Patients aged 10 or over.

Exclusion criteria

• Adults with an incision <5 cm and incision <3cm in children aged under 16 years.
• Patients undergoing procedures with a clean surgical wound only.

Hospital-level data will not be released or published. Country-level analyses will only be conducted with permission of lead investigators from each participating country. Local investigators may access their data across their country to perform country-level analyses (all participating hospitals should consent to their data being used in this way).

Patients will not specifically be blinded to the treatment allocation and those operated under non-general anaesthesia are likely to see the drapes and gowns used. However, most patients are unlikely to be able to recognise and differentiate between the different types of reusable and single use gowns and drapes, meaning unblinded patients are a low risk of bias.

As this is a cluster randomised trial, outcome assessors are likely to know the hospital allocation and are therefore unlikely to be blinded. Assessors will receive formal training to undertake patient record review, in-person wound assessment, or telephone follow-up, as appropriate for their site. Assessors will collect detailed wound-related variables. The primary outcome of SSI will be determined by a computer-based algorithm based on the CDC criteria, using this data.