This study retrospectively investigates the incidence and risk factors for venous thromboembolism (VTE) in patients undergoing maxillofacial surgery. Data were obtained from patients treated between January 2005 and June 2006. Patients’ records were reviewed for complaints and information relating to deep venous thrombosis (DVT) and pulmonary embolism (PE). All patients completed a questionnaire on complaints relating to DVT and PE. The patients were classified according to risk and the incidence of reported DVT and PE was calculated. The study population comprised 411 patients with a mean age of 32 (± 17) years. The median postoperative follow-up period was 53 (23–639) days. None of the patients received thromboembolism prophylaxis. The incidence of VTE in the study group was 0.5%. Logistic regression analysis demonstrated a relationship between body mass index and hospital stay with thromboembolism (p < 0.05). Patients undergoing pre-implant surgery with bone graft proved to be at risk (p = 0.07). The incidence of VTE in oral and maxillofacial surgery seems to be low, but thromboembolism prophylaxis may be justified in patients with clear potential risk factors.
Venous thromboembolism (VTE) comprises two related clinical conditions: deep venous thrombosis (DVT) and pulmonary embolism (PE). Anderson and Spencer. verified the reliability of evidence on specific risk factors for VTE and prepared a guide for identifying patients at risk of developing VTE ( Table 1 ).
|Level of risk||DVT 1 , % Calf||DVT, % proximal||PE 2 , % Clinical||PE, % Fatal|
|Low risk||2||0.4||0.2||< 0.01|
|Minor surgery in patients <40 yr with no additional risk factor|
|Minor surgery in patients with additional risk factor|
|Surgery in patients aged 40–60 yr with no additional risk factors|
|Surgery in patients > 60 yr, or age 40–60 yr with additional risk factors (cancer, prior VTE)|
|Surgery in patients with multiple risk factors (age >40 yr, cancer, prior VTE)|
Several studies on general surgical patients have shown that the risk of developing DVT is less than 3% for patients under 40 years of age and in those who undergo surgery that lasts less than 30 min. The risk increases with age and the complexity and duration of surgery. It is highest in obese patients, in those with a history of VTE and in those with malignancies. Other risk factors include prolonged immobility, use of oral contraceptives, multiple trauma and chronic heart failure. The predictive values of these factors are not equal. The incidence is also dependent on the type of surgery; ranging from 32 to 88% for urological, gynecological, abdominal or orthopedic surgery. The use of routine thromboprophylaxis perioperatively has decreased the incidence to 15–30%.
There is no information on the incidence and potential risk factors of VTE and PE in patients undergoing oral and maxillofacial surgery. The use of VTE prophylaxis in patients undergoing oral and maxillofacial surgery has not received sufficient attention.
The present study was designed to investigate retrospectively the incidence of VTE and PE in patients undergoing oral and maxillofacial surgery without thromboembolism prophylaxis perioperatively. The use of perioperative prophylaxis in oral and maxillofacial surgery is not evidence based so the authors’ department protocol does not prescribe any form of prophylaxis in these patients.
Patients and Methods
All patients treated under general anesthesia in the Department of Oral and Maxillofacial Surgery, between January 2005 and June 2006 were identified using the hospital database. Data concerning the following potential risk factors were collected: patient characteristics, type of surgery, operative factors (operation time, prolonged immobilization), age, gender, weight, height, body mass index (BMI), nicotine use, hormone replacement therapy (use of contraceptives), medical history (presence of diabetes mellitus, cardiovascular disease, malignancy, thrombosis). The patients’ medical records were studied for complaints related to DVT and PE, such as pain, swelling and redness of the leg. Visits from the physician in the postoperative period, and medication use, apart from that used prior to surgery, were noted. All patients were interviewed by telephone using a questionnaire about complaints and physician visits related to DVT and PE.
All patients were classified according to the risk classification in Table 1 .
The incidence of reported DVT and PE was determined using the SPSS 10.0 package. Unvariate relationships between continuous risk factors and DVT and PE were studied using logistic regression analysis. The odds ratio and related 95% confidence interval for each risk factor was assessed, and significant risk factors (p < 0.05) were recorded. Fisher’s exact test was used for the dichotomized risk factors gender, age > 40 years, BMI > 25 and type of surgery.
Only patients undergoing elective surgery were included. Patients undergoing day-care treatments were excluded. Only 3 patients underwent elective trauma surgery; to homogenize the study population, these patients were excluded. In the authors’ department, the trauma patients are treated as acute patients and often treated by a multidisciplinary team as they generally have multiple trauma; these patients were also excluded. Data on oncological surgery were not included in this study because they are performed in the Department of ENT and Head and Neck Surgery. The following types of oral and maxillofacial surgery were performed: oral and dento-alveolar surgery, pre-implant surgery (with or without bone graft), orthognathic surgery, cleft surgery, and reconstructive surgery.
None of the patients received any thromboembolism prophylaxis perioperatively.
The demographic data for patients undergoing each type of surgery type are shown in Table 2 . The study population comprised 411 patients with a mean age of 32.4 (± 17.0) years and a mean BMI of 23.0 (± 4.3) kg/m 2 . The mean operation time was 87.8 (± 51.7) min and the mean hospital stay was 32.6 (± 17.0) h. The median postoperative follow-up period was 53 days (range 23–639 days).
|Patients Male Femal||Age (yrs ± SD)||Operation time (min ± SD)||Hospital stay (hrs ± SD)||BMI (kg/m 2 ± SD)||BMI > 25 kg/m 2 (patients)|
|Dental-alveolar surgery||15||23.7 ± 15.8||43.2 ± 23.3||27.7 ± 4.1||20.8 ± 5.0||4|
|Distraction-osteogenesis||28||21.3 ± 11.0||95.7 ± 32.2||28.3 ± 9.3||20.3 ± 2.6||2|
|Cyst surgery||7||38.0 ± 10.5||41.7 ± 12.5||24.0 ± 1.0||24.6 ± 3.9||4|
|Tumor excision (benign)||17||53.0 ± 18.6||42.5 ± 17.7||24.7 ± 4.0||24.9 ± 4.2||16|
|Gland surgery||8||25.8 ± 19.0||73.8 ± 21.7||24.0 ± 1.0||19.6 ± 2.9||1|
|Implant surgery||6||45.7 ± 10.7||75.0 ± 18.7||24.0 ± 1.0||24.4 ± 2.5||3|
|Pre-implant surgery||18||50.8 ± 13.2||135.0 ± 40.1||68.5 ± 23.7||25.0 ± 3.2||12|
|Reconstructive surgery||10||43.8 ± 12.6||174.7 ± 143.8||50.5 ± 26.4||25.2 ± 3.2||8|
|Cleft surgrey||14||13.8 ± 1.5||86.8 ± 30.7||39.2 ± 14.3||18.8 ± 4.1||1|
|TMJ surgery 1||4||28.3 ± 11.9||113.8 ± 59.1||32.0 ± 11.8||20.1 ± 3.6||1|
|ROSM 2||8||36.4 ± 14.5||78.8 ± 35.4||24.0 ± 0.0||24.1 ± 5.8||7|
|Orthognathic surgery||78||28.9 ± 11.7||88.7 ± 26.3||29.5 ± 10.1||23.7 ± 3.8||48|
Table 3 lists the patients according to type of surgery and risk of thromboembolism. 20 patients were classified as low risk, 302 as moderate risk, 51 as high risk and 38 as highest risk.
|Low risk (patients)||Moderate risk (patients)||High risk (patients)||Highest risk (patients)|
|Tumor excision (benign)||3||11||7||15|
|TMJ surgery 1||0||11||1||0|