Observational study to estimate the proportion of surgical site infection following excision of ulcerated skin tumours (OASIS study).

BACKGROUND Ulceration is a recognised risk factor for SSI, however the proportion of patients developing SSI after excision of an ulcerated skin cancer is unknown. OBJECTIVES To determine the proportion of participants with SSI after surgical excision of an ulcerated skin cancer. Secondary aims included feasibility outcomes to inform the design of a randomised controlled trial to investigate the benefits and harms of peri-operative antibiotics following excision of in ulcerated tumours. METHODS We undertook a multi-centre prospective, observational study of patients undergoing excision of an ulcerated skin cancer between March 2019-March 2020. Prior to surgical excision, surface swabs of the ulcerated tumours of participants recruited from one centre were undertaken to determine organism growth. Four weeks after surgery, all participants were e-mailed or posted the Wound Healing Questionnaire (WHQ) to determine whether they had developed SSI. RESULTS 148 participants were recruited (105 (70.9%) males; mean (standard deviation) age 77.1 years (12.3). Primary outcome data were available for 116 (78.4%) participants of whom 35 (30.2%) were identified to have SSI using the WHQ with a cut-off score of 8 and 47 (40.5%) with a cut-off score of 6. Using the modified WHQ in participants with wounds left to heal by secondary intention, 33 (28.4%) and 43 (37.1%) were identified to have SSI respectively. CONCLUSIONS This prospective evaluation of SSI identified with the WHQ following excision of ulcerated skin cancers demonstrated a high proportion with SSI. The WHQ was acceptable to patients, however further evaluation is required to ensure validity in assessing skin wounds.