Analysis of Risk Factors Associated with Hospital Readmission Within 360 Days After Degenerative Lumbar Spine Surgery in Elderly Patients

Objective: There is a paucity of studies on readmission rates in elderly patients over a period of 360 days after spinal surgery. Methods: We identified 1248 patients older than 70 years who underwent degenerative lumbar spinal surgery from November 2005 to April 2015. We reviewed the patients who were readmitted within 360 days and compared them by univariate and multivariate analysis with the nonreadmitted patients for each period of 0–30, 30–90, 90–180, and 180–360 days postoperatively to determine risk factors for hospital readmission. Results: A total of 1248 patients (733 female, 58.7%) were enrolled in the study. The number of readmitted patients was 37 (2.96%), 94 (7.53%), 145 (11.62%), 182 (14.58%), and 213 (17.07%) at 30, 90, 180, 270, and 360 days, respectively. Surgical site–related problems decreased gradually in the first 0–90 days and slightly increased after then. Non-surgical site–related problems gradually increased with time. Logistic multiple regression analysis showed that electrocardiographic abnormalities, male sex, low hemoglobin levels, asthma, heart disease, intensive care unit admission, low alanine aminotransferase level, high body mass index, and high platelet level were risk factors for readmission. Conclusions: We found that electrocardiographic abnormalities, male sex, low hemoglobin levels, asthma, heart disease, intensive care unit admission, low aspartate aminotransferase level, high body mass index, and high platelet level were risk factors for readmission. As the postoperative observational period became longer, the reasons for readmission tended to be more related to non-surgical site–related problems than to surgical-related problems.