Factors affecting the occurrence of pulmonary embolism after spinal surgery: data from the national administrative database in Japan

Background contextDespite potentially devastating consequences, pulmonary embolism (PE) in patients undergoing spinal surgery remains poorly understood. To the best of our knowledge, few large studies have examined the prevalence and risk factors of PE after spinal surgery.PurposeTo investigate the prevalence of symptomatic PE in patients undergoing elective spinal surgery and to identify clinical variables associated with the occurrence of postoperative PE.Study designA retrospective analysis of data abstracted from the diagnosis procedure combination (DPC) database, a nationally representative database in Japan.Patient sampleWe included all patients with a diagnosis of spinal canal stenosis, disc herniation, spondylosis, spondylolisthesis, trauma, metastatic tumor, or infection who underwent spinal surgery between July 1 and December 31 of 2007 and 2008, respectively.Outcome measuresThe primary end point was defined as the occurrence of postoperative PE during hospitalization. The secondary end point was in-hospital death after postoperative PE.MethodsWe analyzed the association between the occurrence of postoperative PE and clinical variables recorded in the DPC database, including age, sex, comorbidities, location of surgery, primary diagnosis, anterior/posterior approach, use of instrumentation, and duration of anesthesia.ResultsA total of 47,743 patients were identified. Of these, 50 (0.10%) developed PE and four died as a result of PE. Logistic regression analyses revealed that occurrence of PE was associated with older age (70 years or older; odds ratio [OR], 3.15; 95% confidence interval [CI], 1.15–8.69; p=.026) and longer anesthesia time (more than 360 minutes; OR, 2.19; 95% CI, 0.88–5.44; p=.092). Patients with trauma were significantly more likely to have a PE than those with spinal canal stenosis (0.27% vs. 0.09%; OR, 2.86; 95% CI, 1.14–7.18; p=.026).ConclusionsThis retrospective analysis of a nationally representative database identified older age, longer anesthesia time, and spinal trauma as risk factors for increased incidence of postoperative PE. Surgeons should be aware of the increased risk of postoperative PE in these subgroups of patients.