INTRODUCTION. The incidence of postoperative delirium in spine surgery ranges from 12% to 24%. While postoperative delirium is accompanied by longer hospital stays, increased medical costs, higher readmission rates, and higher mortality rates, there are few reports of risk factors and prevention methods for delirium in spine surgery. This study investigated the incidence and prognostic factors of delirium after kyphoplasty for osteoporotic vertebral fractures, and the effectiveness of our early mobilization program on delirium.
METHODS. This retrospective study included 352 patients (mean age, 80.5 ± 7.1 years; range, 65–99 years; 271 women, 81 men) who underwent kyphoplasty for osteoporotic vertebral fractures between January 2018 and September 2023. The Kihoku Super Early Ambulation Program (K-SEAP) initiated in April 2021 is a program in which patients walk under supervision by a physical therapist three hours after surgery to prevent postoperative delirium and to facilitate early acquisition of activities of daily living (ADL). During hospitalization, all patients underwent physical and occupational therapy the day after surgery. Physical therapy included gait training, strengthening exercises for the back muscles and lower extremities, and home exercise instruction. In occupational therapy, patients practiced ADLs, such as dressing, toileting, and bathing. Each therapy was performed five days a week for an hour (total two hours/day). The primary outcome was the presence of postoperative delirium, which was determined retrospectively from medical records. Prognostic factors were age, gender, body mass index (BMI), presence of underlying disease, radiological spinal alignment, bone mineral density, skeletal muscle index assessed by bioelectrical impedance, motor function (grip strength, walking independence, including availability of walking aids), cognitive function (Mini-Mental State Examination, MMSE), time from injury to surgery, presence of K-SEAP, weekend (Friday) or weekday surgery, and patient-reported outcomes (numerical rating scale of back pain, Oswestry disability index, MOS 36-Item Short-Form Health Survey, and EuroQol-5Dimention-5Level) before kyphoplasty. Patients were divided into delirium and nondelirium groups. Data were compared between the groups using the chi-square test and the Mann–Whitney U test. Binary logistic regression using the forward stepwise likelihood ratio method was used to investigate risk factors for delirium. Variables with P values < 0.05 in the univariate analyses were entered as independent variables into the regression analysis.
RESULTS. Postoperative delirium occurred in 23 of 352 patients (7%). Compared with the nondelirium group, the delirium group was older (delirium vs. nondelirium group; 83.9 vs. 80.0 years), mostly male (48% vs. 21%), more patients had weekend surgery (43 vs. 17%), lower BMI (21.0 vs. 22.4 kg/m2), lower MMSE (16 vs. 25 points), and fewer patients received K-SEAP (22 vs. 51%) (P < 0.05). Delirium was significantly associated with K-SEAP (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.06–0.74) and MMSE (OR 0.22, 95% CI 0.06–0.74).
DISCUSSION. The incidence of delirium after kyphoplasty for elderly patients was 7%. K-SEAP was the strongest predictor to prevent postoperative delirium in patients undergoing kyphoplasty. Future studies are needed to assess the effectiveness of early mobilization on clinical outcomes, including costs in elderly patients with osteoporotic vertebral fractures undergoing kyphoplasty.