ASSOCIATION BETWEEN PREOPERATIVE GLYCAEMIC CONTROL (HBA1C) AND EARLY OUTCOMES FOLLOWING PRIMARY HIP AND KNEE ARTHROPLASTY

This study investigates the relationship between Diabetes mellitus (DM), glycated haemoglobin (HbA1c) and postoperative outcomes among patients receiving hip and knee replacement. We conducted a single-centre cohort study of patients receiving primary joint replacement between 2008–2019 in whom preoperative HbA1c was recorded. Cases were categorised by preoperative HbA1c as ‘diabetes’ (≥48mmol/mol), ‘prediabetes’ (≥42mmol/mol and <48mmol/mol), ‘no diabetes’ (<42mmol/mol), or in ‘remission’ (preoperative HbA1c <42mmol/mol but having a historic HbA1c result ≥42mmol/mol). Multivariable logistic regression and restricted cubic splines were used to examine the association between diabetes status, HbA1c and early postoperative outcomes. Analysis of 9,454 cases (18.4% diabetes, 23.5% prediabetes, 49.7% no diabetes, 8.4% in remission) revealed DM was associated with a 50% greater likelihood of experiencing one or more postoperative complications (Odds Ratio (OR) 1.47 (95%CI 1.26–1.71)), a 60% greater risk of acute kidney injury or electrolyte abnormality (OR 1.57 (95%CI 1.33–1.87)), and more than doubling of the risk of postoperative urinary tract infection (OR 2.25 (95%CI 1.15–4.52)) and deep surgical site infection (OR 2.03 (95%CI 1.05–3.86)) compared to individuals without diabetes. There was a substantial increase in complication risk as HbA1c entered prediabetes range with no evidence of a plateau or threshold effect, and a profound reduction in the risk of almost all recorded complications for patients in remission from previously elevated HbA1c. DM was associated with significantly increased risk of almost all measured early postoperative complications following joint replacement, and a more than doubled risk of surgical site infection and postoperative renal complications, highlighting the need for close perioperative monitoring and fluid balance management in these patients. The modelled risk of complications increased rapidly when HbA1c rose into the prediabetes range with no plateau or threshold effect observed. Patients with diabetes and prediabetes who brought their elevated HbA1c into normal range before surgery saw their baseline risk return almost to normal. Interventions to reduce elevated HbA1c, to any degree, may benefit patient outcomes however must be balanced with the risk of iatrogenic harm.