Advanced Trainee in Renal and Acute & General Care Medicine at Northland DHB
Incidence Of Delirium And Associated Risk Factors In Post-Operative Joint Replacements At Whangarei Base Hospital
Thomas Evans, Northland District Health Board, Whangarei, New Zealand
Jennifer Walker, Northland District Health Board, Whangarei, New Zealand
Christopher Hutchinson, Northland District Health Board, Whangarei, New Zealand
Aims The aim of this study was to investigate the incidence of post-operative delirium in patients undergoing elective joint replacement at Whangarei Base Hospital. We aimed to identify risk factors in order to consider screening and management strategies for patients at high risk of delirium.
Methods This was prospective study of 95 consecutive patients over the age of 50 years who were undergoing elective single joint arthroplasty (hip or knee). Patients were screened for delirium twice daily in the post-operative period, using the 4AT rapid assessment test for delirium. The 4AT is a validated clinical instrument that can be used for the detection of delirium (Belleli et al., 2014). Clinical notes were retrospectively reviewed for evidence of delirium, demographic data, co-morbidities, laboratory investigations, and post-operative bladder and bowel function. A stepwise multiple logistic regression was performed to assess association between risk factors and occurrence of delirium. Odds ratio(OR) and 95% confidence intervals (CI) are reported.
Results Delirium occurred in 13 of the 95 patients (13.7%). All patients with delirium were over the age of 65. Deficit in attention was the most commonly observed score on the 4AT. In the multivariate analysis, pre-existing cognitive impairment was the strongest predictor of post-operative delirium (OR 42.6, CI 3.4 to 541.2, p = 0.04). Age of 72 years or above (OR 9.0, CI 1.3 to 62.2, p = 0.025) and pre-operative use of hypnotic medications (OR 7.8, CI 1.2 to 49.9, p = 0.031) also demonstrated statistically significant association.
Conclusion In an elective surgical setting, patients at risk of delirium can be identified pre-operatively to allow interventions to be instituted, and to ensure clinicians, patients and their family are aware of the risk to the individual patient.
Bellelli, G., Morandi, A., Davis, D. H. J., Mazzola, P., Turco, R., Gentile, S., … MacLullich, A. M. J. (2014). Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people. Age and Ageing, 43(4), 496–502. http://doi.org/10.1093/ageing/afu021