Study Designs, Clinical Epidemiology, and Diagnostic Test Accuracy in Perioperative Medicine — WACS Viva & Clinical Scenarios (Statistics & Evidence-Based Practice)

Exam-style study designs, clinical epidemiology, and diagnostic test accuracy in perioperative medicine viva scenarios with examiner probes and model answers…

Scenarios covered

• SCENARIO 1: You are investigating a newly introduced bedside screening test for predicting difficult mask ventilation in adult maxillofacial trauma patients. You test 200 consecutive patients presenting to the emergency operating suite against the reference gold standard of documented difficult mask ventilation during induction. The test correctly identifies 30 out of 40 difficult ventilations and correctly clears 140 out of 160 normal ventilations. As the research lead, how do you construct the 2x2 diagnostic table and calculate/interpret the Sensitivity, Specificity, Positive Predictive Value (PPV), Neg
• SCENARIO 2: You are designing a study to assess whether intraoperative administration of tranexamic acid reduces the requirement for allogeneic blood transfusion in major open myomectomy for huge uterine fibroids (uterine size ≥ 20 weeks). Discuss the comparative strengths and weaknesses of conducting this study as a double-blind randomised controlled trial versus a prospective matched cohort study in your hospital.
• SCENARIO 3: A published paper evaluates a new goal-directed fluid therapy (GDFT) protocol during major abdominal emergency surgeries. The incidence of postoperative acute kidney injury (AKI) was 8% in the GDFT group compared to 20% in the standard fluid management group. How do you calculate the Relative Risk (RR), Relative Risk Reduction (RRR), Absolute Risk Reduction (ARR), and the Number Needed to Treat (NNT), and what is the clinical relevance of these parameters for your practice?
• SCENARIO 4: You plan a hospital-based case-control study to identify independent risk factors for perioperative cardiac arrest during emergency paediatric anaesthesia in your teaching hospital over the last 10 years. Outline your methodology for case and control selection, strategies to minimize selection and recall bias, and the appropriate measure of association you will calculate.