HSC Section 3 - Trauma, Critical Care and Sleep Medicine

V ENOUS THROMBOEMBOLISM IN OTOLARYNGOLOGY

demonstrates a narrow CI. After subgroup and meta- regression analyses, we were able to explain a portion of this heterogeneity using the OHNS subgroup but this did not change the overall random effects model estimates. The results of our quantitative analyses were in keeping with the qualitative results across studies and, in our opin- ion, the observed heterogeneity between studies does not change the clinical implications of our findings. As we have encountered only one level 1 study, there is a definite need for more high-quality level 1 evidence in the domain of VTE prophylaxis in OHNS. One obsta- cle to implementing such a study is the large number of patients required because of the very low incidence of VTEs in our patient population. An important option for future research would be to evaluate the optimal chemo- prophylaxis regimen in higher risk patients, as has been done in other specialties. 1 In conclusion, the decision to introduce chemoprophy- laxis in OHNS patients must take into account the signifi- cantly increased risk of bleeding. Our review suggests that chemoprophylaxis is unnecessary and adds bleeding risk in OHNS patients at large. In patients with SCC or for whom free flap reconstruction is planned, the risk of VTE is significantly higher, and use of chemoprophylaxis should be made on a case-by-case basis, given the increased risk of bleeding complications. Multiple risk assessment models exist to stratify these patients and should be given consideration on a case-by-case basis. REFERENCES 1. Gould MK, Garcia DA, Wren SM, et al. Prevention of VTE in nonorthope- dic surgical patients: Antithrombotic Therapy and Prevention of Thrombo- sis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012;141(2 Suppl):e227S–e277S. 2. Kahn SR, Lim W, Dunn AS, et al. Prevention of VTE in nonsurgical patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012;141(2 Suppl):e195S–e226S. 3. Falck–Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012;141(2 Suppl): e278S–e325S. 4. Lakhani R, Narwani V, Bromby A, Hilger AW. Venous thromboembolism in ENT surgery: a review of the literature and completed audit cycle of adherence to national guidance. Eur Arch Otorhinolaryngol 2013;270: 2559–2564. 5. Papel ID, Goldstein JC. Centennial celebration of otolaryngology–head and neck surgery in the United States: history of the American Academy of Otolaryngology–Head and Neck Surgery. Otolaryngol Head Neck Surg 1996;114:1–3. 6. Bahl V, Shuman AG, Hu HM, et al. Chemoprophylaxis for venous throm- boembolism in otolaryngology. JAMA Otolaryngol Head Neck Surg 2014; 140:999–1005. 7. Chiesa Estomba C, Rivera Schmitz T, Ossa Echeverri CC, Betances Reinoso FA, Osorio Velasquez A, Santidrian Hidalgo C. The risk of venous thromboembolism in ENT and head & neck surgery. Otolaryngol Pol 2015;69:31–36. 8. Clayburgh DR, Stott W, Cordiero T, et al. Prospective study of venous thromboembolism in patients with head and neck cancer after surgery. JAMA Otolaryngol Head Neck Surg 2013;139:1143–1150. 9. Garritano FG, Andrews GA. Current practices in venous thromboembolism prophylaxis in otolaryngology–head and neck surgery. Head Neck 2016;38 Suppl 1:E341–E345. 10. Moher D, Liberati A, Tetzlaff J, Altman DG; PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Int J Surg 2010;8:336–341. 11. Stroup DF, Berlin JA, Morton SC, et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA 2000;283: 2008–2012. 12. Karagama YG, Anari S, Lancaster JL, Karkanevatos A, Jones TM, Sherman IW. Conservative management of epistaxis: are we putting

studies reported similar rates of bleeding complications. The only study in which bleeding complication incidence was available for SCC or free flap cases showed an inci- dence of 8.1% in SCC or free flap cases, and 1.1% in other patients. 6 This was confounded by nonhomogeneous use of thromboprophylaxis. Therefore, further large stud- ies would be warranted to confirm that the benefit of thromboprophylaxis in free flap or SCC cases outweighs the bleeding risks. Although based on the CHEST guidelines, only sequen- tial compressive devices would be recommended in SCC or free flap cases, chemoprophylaxis might be appropriate for a specific subset of patients. Pharmacologic options include unfractionated heparin, LMWH, fondaparinux, and vitamin K antagonists. 15 There is a wide range of chemoprophylaxis regimens used in OHNS patients; therefore, we cannot conclude on an optimal regimen based on our systematic review and meta-analysis. More- over, we have not found that introduction of chemopro- phylaxis significantly reduces VTE in OHNS patients at large. It is of the utmost important to identify which subset of OHNS patients might benefit the most from chemopro- phylaxis. The Caprini score estimates VTE risk using a point system for various risk factors, although this model was not developed using rigorous statistical methods. 1 The Caprini score was recently validated in a retrospec- tive cohort of OHNS patients. 16 In the Caprini score, lev- els of 6 and below, 7 to 9, or 9 or greater are represented, and the incidence of VTEs was 0.0%, 3.0%, and 13.1%, respectively, despite appropriate thromboprophylaxis. 16 The authors concluded that, despite appropriate thrombo- prophylaxis, VTE might not be avoidable in OHNS patients with extremely high Caprini scores (9 or greater). The Caprini score, however, includes some variables that were later found not to be associated with VTE risk. 1 Another study 17 identified specific risk factors among patients with head and neck cancer undergoing resection and free flap reconstruction on multivariate analysis, and has shown that increased age, increased body mass index, packed red blood cell transfusion, and history of VTE to be significant predictors of possible VTEs. Our study needs to be considered in the context of the study design and its limitations. Whenever performing a meta-analysis, to pool data from similar studies to esti- mate an outcome or effect, the heterogeneity within and between studies informs whether they can be pooled. Giv- en the limited literature on the topic, a broad search strat- egy and inclusion criteria were incorporated to have a sufficient number of studies to meta-analyze. Given this approach, we a priori expected significant heterogeneity. This was demonstrated particularly in our large pooled analyses of VTE (Figure 2A) and bleeding complications (Figure 2C) in OHNS. However, the quantification of het- erogeneity is only one aspect of variability assessment across studies and is by no means the most important measure of the validity of a meta-analysis. 33 Despite het- erogeneity in years, size, study/database type, observation period for outcome, and OHNS subgroup (Table 1) the analyses in question (Figure 2A and 2C) do not demon- strate large variations in event rates between studies that are clinically meaningful and the random effects estimate

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