Alcoholic Chlorhexidine or Alcoholic Iodine Skin Antisepsis Study

INTERVENTION: The aim of this cluster randomised controlled trial is to compare the incidence of superficial wound complications in all patients undergoing elective prosthetic hip or knee replacement surgery receiving surgical skin preparation with either: 0.5% chlorhexidine gluconate in 70% alcohol or 1% iodine in 70% alcohol. CONDITION: Prosthetic joint replacement surgery Superficial wound complications PRIMARY OUTCOME: Superficial surgical wound complications, specificially superficial incisional surgical site infections (as defined by the Centers for Disease Control / National Healthcare Safety Network) and prolonged wound ooze (wound ooze requiring intervention, such as superficial surgical debridement). These will be assessed clinically. INCLUSION CRITERIA: Participants undergoing hip or knee replacement surgery SECONDARY OUTCOME: Assessment of the causative microorganisms of surgical site infections. The diagnosis of surgical site infections is clinical and is according to the CDC/NHSN definition). Economic analysis including cost‐effectiveness of surgical skin preparation. We will apply health economic modelling to estimate the potential cost‐effectiveness of 0.5% chlorhexidine in 70% alcohol compared with 1% iodine in 70% alcohol. Decision analysis will be used to compare the downstream consequences of SSP. The incorporation of Markov and life‐tabling techniques will allow for the modelling of outcomes beyond one year. The main output of interest in health economic modelling is incremental cost‐effectiveness ratios in terms of net costs per unit of health gain. Net costs will comprise the costs of the SSP agents minus costs saved from the reduction in downstream health services utilization. Health gains can be measured in a variety of ways. In our study, other than clinical outcomes, we will be also estimating years of life gained and quality‐adjusted life years (QALYs) gained. Both are enabled by the collection of time‐to‐outcome data and the latter also by collection of quality of life data. All health economic analyses will be undertaken in accordance with recommended approaches, such as 5% discounting of estimated future costs and health gains. To account for any uncertainty in the data inputs for health economic modelling, sensitivity and uncertainty analyses will be undertaken via Monte Carlo simulation. The incidence of superficial surgical wound complications according to the joint replaced (knee or hip). Superficial surgical wound complications include either superficial incisional surgical site infections (as defined by the CDC / NHSN) and prolonged wound ooze (wound ooze requiring intervention, such as superficial surgical debridement). These will be assessed clinically. Undesirable adverse consequences from surgical skin preparation (SSP) including toxicity and allergies. This will be assessed clinically.