Risk factors for onset of delirium after neck of femur fracture surgery: a prospective observational study

Background: Delirium is a common complication after surgery in the elderly that leads to increased length of stay and other adverse outcomes. The aim of this study was to better understand the exact causes of post-operative delirium in patients undergoing surgery for neck of femur (NOF) fractures. Methods: We performed a prospective cohort study of 381 consecutive patients undergoing surgery for NOF fractures at a single institution. Baseline cognitive status and risk factors were recorded on admission. Post-operative cognitive status was assessed at regular intervals until discharge. Binary logistic regression was performed to identify independent predictors of delirium. Results: Patients who developed post-operative delirium (n=70) were significantly older (average age 83 vs. 78, p=0.019) and more likely to be female (79% vs. 67%, p=0.062) than non-affected patients. The presence of delirium was associated with increased length of stay (13 vs. 10 days, p=0.001) and 1-year mortality (25.7% vs. 15% p=0.03). Independent predictors of delirium included age >= 65 years (Odds Ratio=5.8), presence of anaemia (OR=2.9), hypoxia (OR=2.86), cardiac disease (OR=2.8), Chronic Obstructive Pulmonary Disease (OR=2.5), new onset electrolyte imbalance (OR=2.2) and renal failure (OR=1.9). Conclusion: Overall analysis demonstrated an increased incidence of delirium in older females with greater comorbid conditions. It was also found to be associated with increased morbidity and mortality. We recommend clinicians put greater effort into recognising risk factors of delirium and diagnosing it in a timely manner to mitigate its effects.