Time-to-event analyses of lower-limb venous thromboembolism in aged patients undergoing lumbar spine surgery: a retrospective study of 1620 patients

Abstract

After spine surgery, venous thromboembolism (VTE) is not uncommon in aged patients. This study investigates time-to-event risk factors of postoperative VTE based on medical records of aged patients (age≥60 yr) between January 2013 and December 2018. All participants had undergone lower extremity ultrasonography pre- and postoperatively at the first, second, fourth, eighth, and twelfth weeks. Mann-Whitney U tests and chi-square tests were used for univariate analyses, and Cox regression was utilized for multivariate analyses. A total of 1620 cases were recruited, VTE group (N=382, 23.6%) and non-VTE group (N=1238, 76.4%), aged 67 (IQR 11) years and 65 (IQR 6) years, respectively. The univariate analyses indicated significant differences between the VTE and non-VTE groups regarding advanced age, VTE history, hypertension, fusion, hospital stay, FIB, HDL, D-dimer, and TC (all P<0.05). The Cox regression showed that advanced age (OR=1.108; 95% CI, 1.091–1.126), VTE history (OR=4.962; 95% CI, 3.849–6.397), and hypertension (OR=1.344; 95% CI, 1.084–1.667) were the risk factors for postoperative VTE (P<0.05). The time-to-event analyses indicated that the hazard of VTE formation was highest in the first postoperative week. In conclusion, advanced age, VTE history, and hypertension are main risks for VTE formation, particularly in the first postoperative week.

Venous Thromboembolism Prophylaxis in Elective Spine Surgery

“…Few publications have exclusively examined VTE incidence in elective spinal surgery patients, however, the available literature suggests an incidence between 0.2% and 31%. [5][6][7][8][10][11][12][13][14][15][16][17]21,22 As many of these types of publications are international, it is imperative to note that guidelines for standard of practice regarding VTE prophylaxis in spine patients differs and thus incidence of VTE may differ. Studies of this nature are also likely retrospective designed, allowing for variation in prophylaxis protocols, imaging modalities, postoperative mobilization, and follow-up times.…”

“…VTE risk factors in patients undergoing spine surgery have been identified and stratified in the literature based on demographic variables such as age, sex, and weight as well as surgical variables such as vertebral level and surgical approach. A multitude of risk factors have been attributed to an increased risk of VTE; however, advanced age [22][23][24][25] is the most commonly reported risk factor amongst published studies.…”

“…A 2019 time-to-event analyses of lower extremity VTE in lumbar spine surgery patients recorded Ultrasound findings preoperatively, and on postoperative weeks 1, 2, 4, 8, and 12. 22 Of the 1620 total patients included, 382 had a VTE. Their most notable finding was that VTE formation is the highest in the first postoperative week.…”

“…The most recent NASS guidelines 22 recommend initiation of mechanical prophylaxis just prior to or at the beginning of elective spine surgery and continue until the patient is fully ambulatory. The guidelines state that chemical prophylaxis is safe to initiate the day of elective spine surgery and that an ideal duration has yet to be decided.…”

“…Few publications have exclusively examined VTE incidence in elective spinal surgery patients, however, the available literature suggests an incidence between 0.2% and 31%. 5 -8,10 -17,21,22…”