Pre-operative hemoglobin level and use of sedative-hypnotics are independent risk factors for post-operative delirium following total knee arthroplasty.
BACKGROUND
Delirium is a well-known complication following surgery, especially with the increasing age of patients undergoing surgery. The increasing demands resulting from a prolonged healthy life expectancy has resulted in more arthroplasties despite their age and existing comorbidities. The purpose of this study is to explore the various risk factors that may contribute to delirium in unilateral and bilateral total knee arthroplasties in the elderly population.


METHODS
170 patients who underwent unilateral or bilateral total knee arthroplasties were analyzed retrospectively for delirium. Age, sex, comorbidities, use of sedative-hypnotics, peri-operative blood loss, pre- and post-operative laboratory blood test results were investigated and analyzed.


RESULTS
The incidence of post-operative delirium was 6.5% (11 out of 170 patients) with a mean age of 79.5 (± 6.9) years, compared to 73.0 (± 9.0) years in the non-delirium group. Higher age, use of sedative-hypnotics, low pre-operative Hb and Ht, low post-operative Hb, Ht and BUN were observed in the delirium group. Multivariate logistic regression analysis identified that the use of sedative-hypnotics and pre-operative Hb level were independent risk factors for post-operative delirium after TKA. The odds ratios for the use of sedative-hypnotics and pre-operative Hb level were 4.6 and 0.53, respectively. Receiver operating characteristic curve analysis showed that pre-operative Hb of less than 11.1 g/dL was a predictor for the development of delirium, with a sensitivity of 54.6% and a specificity of 91.6%.


CONCLUSION
Patients with a pre-operative Hb level of < 11.1 g/dL or those using sedative-hypnotics are associated with post-operative delirium. Peri-operative management and preventative measures are therefore needed to reduce the risks of post-operative delirium in such patients.
['Kijima|Eiji|E|', 'Kayama|Tomohiro|T|', 'Saito|Mitsuru|M|', 'Kurosaka|Daisaburo|D|', 'Ikeda|Ryo|R|', 'Hayashi|Hiroteru|H|', 'Kubota|Daisuke|D|', 'Hyakutake|Takashi|T|', 'Marumo|Keishi|K|']
D000367:Age Factors D000368:Aged D019645:Arthroplasty, Replacement, Knee D016063:Blood Loss, Surgical D016022:Case-Control Studies D015897:Comorbidity D003693:Delirium D005260:Female D006454:Hemoglobins D006801:Humans D006993:Hypnotics and Sedatives D015994:Incidence D008297:Male D008875:Middle Aged D011183:Postoperative Complications D011184:Postoperative Period D057234:Preoperative Period D012189:Retrospective Studies D012307:Risk Factors D012680:Sensitivity and Specificity
Sedative-hypnotics Delirium Total knee arthroplasty Elderly Anemia Orthopaedic surgery Post-operative complications