At the 2019 meeting of the International Society for the Advancement of Spine Surgery (ISASS; 3–5 April, Anaheim, USA), Erik Wang of NYU Langone Health (New York, USA) presented the results of a study reviewing the rates of hospital-acquired venous thromboembolism (HA-VTE) and the prevalence of known risk factors in patients who developed HA-VTE among both neurosurgical and orthopaedic spine surgery patients. He concluded that, among those who sustained a VTE, neurosurgical patients had higher rates of active cancer and there were more patients over the age of 60 years, while orthopaedic patients had higher estimated blood loss and rates of anterior/posterior surgery.
According to lead author Charla R Fischer (NYU Langone Health, USA) and colleagues: “This highlights the different patient populations between the two departments and the need for individualised thromboprophylaxis regimens.” They suggest: “A multicentre study may further elucidate the reasons why certain procedures and diagnoses are more associated with HA-VTEs, as well as the difference between spine disciplines.”
Fischer and colleagues note that VTE is the number one preventable, hospital-acquired cause of morbidity and mortality in the USA, and estimates of total annual healthcare costs attributable to VTE range from US$7,594–16,644 per patient, up to US$10 billion annually.
The investigators found that the rate of HA-VTE was 0.61% (32/5,283) among orthopaedic patients compared to 1.87% for neurosurgery patients, giving an average rate of 0.94% (67/7,089) among the whole patient population. Additionally, among patients who developed a HA-VTE, orthopaedic patients had higher estimated blood loss (2,436ml vs. 1,176ml, p=0.006), higher rates of anterior–posterior surgery (22.58% vs. 0%, p=0.004) and more patients over the age of 60 (80% vs. 50%, p<0.001). Postoperative anticoagulation was found to be initiated sooner in neurosurgery patients (postoperative day: 1.26 vs. 3.19, p<0.001).
Fischer and colleagues note that significant independent patient risk factors for VTE included treatment in the neurosurgery department (odds ratio [OR] 3.521, 95% confidence interval [CI] 2.11–5.882, p<0.001), the cervical procedure level (OR 0.343, 95% CI 0.134–0.879, p=0.026) and fracture diagnosis (OR: 8.25, 95% CI 1.471–46.26, p<0.001).
The investigators describe the study as a retrospective chart review of all spine surgery patients at NYU Langone Health from 1 January 2013 to 31 July 2017, in which the rates of HA-VTE and the prevalence of known HA-VTE risk factors among these patients was evaluated. They define HA-VTE as either inpatient discharge that was diagnosed with a deep venous thrombosis (DVT) or pulmonary embolism (PE) not present on admission, or a discharge that was readmitted within 30 days of index discharge with a principal diagnosis of DVT or PE.
Furthermore, demographic data was collected for gender, age, ethnicity, BMI, length of hospital stay and number of spinal levels involved in surgery. The prevalence of risk factors, surgical factors, procedure types, preoperative diagnoses and surgical diagnosis-related groups (DRGs) was compared between patients with and without HA-VTE, between patients undergoing procedures with orthopaedic surgery and neurosurgery departments, and between patients at different hospital facilities at NYU Langone Health.
The investigators carried out a univariate analysis for categorical variables, an independent student’s t-test for continuous variables and a multivariate logistic regression to determine the independent of risk factors.