Abstract
We aimed to investigate the association between obesity and deep venous thrombosis (DVT) in a country with a high prevalence of obesity. This is a retrospective cohort study of patients who presented with DVT between 2008 and 2012. Data were analyzed and compared based on body mass index (BMI), and patients were classified into normal (<25), overweight (≥25 to <30), obese I (30 to <35), obese II (35 to <40), and obese III (≥40). Among 662 patients with DVT, 28% were overweight and 49% were obese. The mean age was 50.3 (16.5) years, and 51% were females. Diabetes mellitus and prior venous thromboembolism were significantly higher among obese patients. History of malignancy was more common in nonobese patients. Protein S and antithrombin III deficiency and hyperhomocysteinemia were more prevalent among morbid obese patients. Also, obese patients had higher incidence of thrombosis in the distal veins (P = .03). Warfarin use and long-term therapy were more frequent in obese than nonobese. Postthrombotic syndrome was comparable in obese and nonobese groups. Recurrent DVT was higher in obese I (P < .01), whereas mortality rates were greater in nonobese groups (P = .001). Malignancy, diabetes mellitus, and common femoral vein involvement were predictors of mortality, whereas BMI ≥30 was the predictor of survival. Cox regression models showed that after adjusting for age, sex, pulmonary embolism, and duration of warfarin treatment, BMI ≥40 had better survival (hazard ratio: 0.177, 95% confidence interval: 0.045-0.691, P = .013). There is a significant association between obesity and DVT. Obese patients have characteristic risk factors and better survival. This obesity paradox needs further studies to assess its clinical and pharmacotherapeutic implications.
Keywords: obesity, deep vein thrombosis, pulmonary embolism, postthrombotic syndrome, mortality
Introduction
The global prevalence of obesity is rapidly expanding, with alarming figures in the high-income developed and rapidly developing countries.1 Obesity is a predisposing factor of chronic venous insufficiency as well as venous stasis. Also, obesity could predispose to increase in the intra-abdominal and femoral vein pressures. This will accelerate the inflammation and increase the femoral vein diameter as well as decrease the venous flow.2 In addition to this, obesity confers a synergistic effect with the preexisting comorbidities to increase the risk of deep venous thrombosis (DVT).3,4
It has been suggested that patients with increasing body mass index (BMI) above the normal range are more susceptible to the development of venous thromboembolism (VTE) in terms of DVT and pulmonary embolism (PE).3 Furthermore, obesity is identified as a significant independent risk of VTE with higher complication and recurrence rates.5–8 Several population-based studies have demonstrated that obese patients have 2 to 5 times higher risk of developing VTE than nonobese patients.5,9–11 A recent case–control study of 265 participants showed that patients with overweight or obesity had a 3- or 5-fold increased risk of developing VTE, respectively.12 This could be explained by the fact that increased body weight poses a prothrombotic status that alters the coagulation profile and impairs fibrinolytic activity.4,5,13
There is a rising concern regarding the rate of obesity and its associated comorbidities in the Arab Middle East region, particularly in Qatar, in which the rate of obesity has been reported to be as high as 33% with a predominance of female over male gender.14 There is a lack of information on the effect of obesity on the development of VTE from our region in the Middle East. Herein, we evaluate the association between obesity and DVT and its outcome in the state of Qatar.
Methods
A retrospective cohort study of prospectively collected data was conducted for all patients presenting with DVT and who underwent serial Doppler ultrasonography between January 2008 and December 2012 with a 1-year clinical follow-up period. Patients were enrolled from outpatient clinics, inpatient wards, and intensive care units. Data collection included patients’ demographics, BMI, clinical presentation (ie, localized tenderness, entire leg swelling, calf swelling of >3 cm compared to the other leg, and pitting edema), site (left vs right) and localization (proximal vs distal) of DVT, risk factors, laboratory investigations (d-dimer and coagulation profile), radiological findings, management, hospital length of stay, duration of follow-up, occurrence of PE, postthrombotic syndrome (PTS), and mortality. Patients were followed up for routine clinical care per standard practice. The term VTE indicates either DVT or PE or both.
Deep venous thrombosis in our series was diagnosed by clinical presentation, laboratory investigations, and color Doppler ultrasonography. The procedure for Doppler ultrasonography was primarily based on examination of all patients with GE Logic 9, Logic E9, or Philips IU22 (San Jose, CA) using high-frequency or multi-frequency probes. Deep veins were examined from the common femoral vein (CFV) up to the distal posterior tibial vein (PTV) for compressibility, spontaneous flow, and augmentation by distal compression and Valsalva maneuver using gray scale imaging, color flow imaging, and pulsed wave Doppler. The examination was also extended to both the saphenofemoral junction and saphenopopliteal junction.
Pulmonary embolism was identified by clinical assessment, echocardiography, and computed tomography scan examination. Briefly, all patients were examined using Siemens Somatom Sensation 16- or 64-slice machine. Pulmonary arterial phase bolus tracking through main pulmonary trunk was done followed by aortic phase immediately following pulmonary arterial phase. In pregnant patients, only pulmonary arterial phase was performed. Moreover, 3-dimensional reconstruction was performed, if indicated. Postthrombotic syndrome was described previously as leg pain, swelling, redness, and ulcers in patients with prior DVT.15
Patients with DVT were categorized according to BMI as follows: normal BMI (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese individuals (≥30 kg/m2). Moreover, obese patients were also categorized as obese grade I (30-34.9 kg/m2), obese grade II (35-39.9 kg/m2), and morbid obese grade III (≥40 kg/m2).16 Metabolic syndrome refers to a cluster of obesity, high triglyceride level, low high-density lipoprotein cholesterol, hypertension, and diabetes mellitus.17
Statistical Analysis
Data were reported as percentage, mean (standard deviation), and median and range, when applicable. Comparison between respective groups was performed using One-way analysis of variance (ANOVA) for continuous variables, and Pearson χ2 test was used to compare proportions between the groups for categorical variables. Multivariable logistic regression analysis was performed to determine the predictors of mortality after adjusting for potential relevant covariates that were significant by univariate analysis such as age, sex, prior DVT, prior PE, diabetes mellitus, dyslipidemia, hypertension, BMI, myocardial infarction, malignancy, antithrombin III deficiency, PTV thrombosis, CFV, and iliac vein thrombosis. Data were presented as odds ratio (OR) and 95% confidence interval (CI). A significant difference was considered when the 2-tailed P value was ≤.05. Kaplan-Meier curve was constructed to display survival. Cox regression analysis was performed to assess the hazard ratio (HR) and 95% CI for the risk of mortality during the follow-up. Patients were censored at the time of death or lost to follow-up. Data analysis was carried out using the Statistical Package for Social Sciences version 18 (SPSS Inc, Chicago, Illinois).
Results
Of the total 6420 patients investigated for DVT, 662 (10.3%) had a confirmed diagnosis of DVT using Doppler ultrasonography. The mean age of the patients was 50.3 (16.5) years, and 51% of them were females. The mean and median BMI were 31 (8) kg/m2 and 29 (13-66), respectively. Figure 1 shows a comparison among different age-groups and BMI status. For age 40 to 59 years, 60 to 74 years, and ≥75 years, a significant association was observed between obesity and DVT when compared to normal BMI. However, the occurrence of DVT in younger age patients (<40 years) was comparable among obese and normal BMI groups.
Figure 1.
Comparison among different age-groups and body mass index (BMI) status.
Normal, Overweight, and Obese Patients
The 3 groups were comparable for age, gender, and ethnicity (Table 1). Higher proportion of DVT with excess body weight was diagnosed at outpatient clinics, whereas patients diagnosed with DVT at inpatient wards were frequently having normal BMI (P = .04). Presence of diabetes mellitus, abnormal coagulation factors, and history of DVT and PE was significantly higher among obese when compared to normal and overweight patients. On the other hand, there was a higher prevalence of malignancy in normal BMI patients (P < .03). The frequency of Doppler ultrasound follow-up performed in obese patients was significantly higher than that of normal weight patients, 3 (1-17) vs. 2 (1-20); P = .001.
Table 1.
Demographics and Clinical Presentation of DVT by BMI Status.a
| Normal Weight (BMI < 25), n = 151 (23%) | Overweight (BMI ≥ 25-29.99), n = 186 (28%) | Obese (BMI ≥ 30), n = 325 (49%) | P | |
|---|---|---|---|---|
| Female | 77 (51.0%) | 85 (45.7%) | 175 (53.8%) | .21 for all |
| Male | 74 (49.0%) | 101 (54.3%) | 150 (46.2%) | |
| Age, mean (SD) | 48 (20) | 50 (18) | 51 (16) | .22 |
| Arab Qatari | 39 (25.8%) | 37 (19.9%) | 91 (28.0%) | .12 |
| Diagnosis at | ||||
| Outpatient clinics | 83 (55.0%) | 121 (65.1%) | 217 (66.8%) | .04 for all |
| Inhospital wards | 68 (45.0%) | 65 (34.9%) | 108 (33.2%) | |
| Number of ultrasounds | 2 (1-20) | 2 (1-9) | 3 (1-17) | .001 |
| Risk and comorbidities | ||||
| Diabetes mellitus | 33 (21.9%) | 41 (22.0%) | 113 (34.8%) | .001 |
| Abnormal coagulation | 33 (22.0%) | 33 (17.7%) | 91 (28.0%) | .02 |
| History of DVT | 17 (11.3%) | 32 (17.2%) | 97 (29.8%) | .001 |
| History of PE | 3 (2.0%) | 7 (3.8%) | 23 (7.1%) | .04 |
| Malignancy | 32 (21.2%) | 34 (18.3%) | 40 (12.3%) | .03 |
| Pregnancy | 9 (6.0%) | 19 (10.2%) | 29 (8.9%) | .37 |
| Oral contraceptives | 1 (0.7%) | 4 (2.2%) | 8 (2.5%) | .41 |
| History of recent surgery | 18 (11.9%) | 22 (11.8%) | 44 (13.5%) | .81 |
| History of travel | 5 (3.3%) | 13 (7.0%) | 11 (3.4%) | .12 |
| Hypertriglyceridemia | 12 (7.9%) | 14 (7.5%) | 47 (14.5%) | .03 |
| Hyperdyslipidemia | 31 (20.5%) | 43 (23.1%) | 110 (33.8%) | .003 |
| Hypertension | 49 (32.5%) | 53 (28.5%) | 141 (43.4%) | .002 |
| Lower limb (LL) involvement | ||||
| Left LL | 57 (39.3%) | 70 (39.1%) | 111 (35.0%) | .66 for all |
| Right LL | 78 (53.8%) | 95 (53.1%) | 178 (56.2%) | |
| Bilateral LL | 10 (6.9%) | 14 (7.8%) | 28 (8.8%) | |
| Anatomic location | ||||
| Iliac involvement | 17 (11.3%) | 11 (5.9%) | 14 (4.3%) | .01 |
| Popliteal vein | 104 (68.9%) | 124 (66.7%) | 245 (75.4%) | .08 |
| Common femoral vein | 88 (58.3%) | 92 (49.5%) | 141 (43.4%) | .01 |
| Posterior tibial vein | 96 (63.6%) | 130 (69.9%) | 244 (75.1%) | .03 |
| Treatment | ||||
| Enoxaparin | 113 (74.8%) | 153 (82.3%) | 256 (78.8%) | .25 |
| Warfarin | 98 (64.9%) | 133 (71.5%) | 256 (78.8%) | .005 |
| Aspirin | 46 (30.5%) | 65 (34.9%) | 129 (39.7%) | .13 |
| Dalteparin | 20 (13.2%) | 31 (16.7%) | 57 (17.5%) | .49 |
| Heparin | 15 (9.9%) | 21 (11.3%) | 31 (9.5%) | .81 |
| Duration of warfarin treatment, months | 3 (1-46) | 6 (1-98) | 6 (1-89) | .001 |
| Warfarin for life | 15 (9.9%) | 23 (12.4%) | 69 (21.2%) | .002 |
| Plavix (clopidogrel) | 7 (4.6%) | 15 (8.1%) | 40 (12.3%) | .02 |
| Thrombolytic therapy | 1 (0.7%) | 2 (1.1%) | 7 (2.2%) | .39 |
| Postthrombotic syndrome | 72 (47.7%) | 93 (50.0%) | 163 (50.2%) | .87 |
| Pulmonary embolism | 10 (6.6%) | 30 (16.1%) | 41 (12.6%) | .03 |
| Mortality | 34 (22.5%) | 29 (15.6%) | 37 (11.4%) | .007 |
Abbreviations: BMI, body mass index; DVT, deep vein thrombosis; PE, pulmonary embolism; SD, standard deviation.
a N = 662.
Bilateral lower limb (LL) DVT was observed in 52 (8%) cases, left LL involvement was seen in 351 (55%) cases, and right LL in 238 (37%) cases. No significant difference was observed among the 3 groups for the involvement of LL DVT (right, left, and bilateral). With respect to anatomic location, the occurrence of thrombosis in the popliteal vein was comparable among the 3 groups. Obese patients tended to have a higher incidence of thrombosis in the PTV (P = .03) than normal weight patients. In contrast, thrombosis in the CFV and iliac vein was higher among normal weight patients in comparison to obese patients (P = .01).
Thrombolytic therapy was only given for 10 cases: 7 of them were obese and 5 had PE. Warfarin (78.8% vs 64.9%; P = .005) and clopidogrel (12.3% vs 4.6%; P = .02) were frequently used by obese when compared to normal weight patients. Higher proportion of obese patients were on lifelong warfarin treatment (21.2% vs 9.9%; P = .002) than normal weight patients. Also, the duration of warfarin treatment was longer in overweight and obese patients than that of patients with normal BMI (P = .001).
Postthrombotic syndrome was identified in 56.2% of patients with characteristic presentations of calf pain (74%), leg edema (60%), and leg ulcer (3.7%). The incidence of PTS was comparable among the 3 groups. Pulmonary embolism complicating DVT was greater in overweight and obese patients than normal weight patients (16%, 12.6%, and 6.6%, respectively, P = .03). The overall mortality rate was 15% (n = 100), and the mortality rate was significantly higher among normal BMI patients (22.5%) in comparison to obese (11.4%) and overweight (15.6%) patients (P = .007).
Breakdown of BMI Into 5 Groups
Among the 325 obese patients, 156 (48%) had obesity grade I, whereas morbid obesity with grades II and III was found in 98 (30%) and 71 (22%) patients, respectively. Table 2 shows the comparison of demographics and clinical characteristics of DVT in the 5 BMI groups. Patients with grade III obesity were more likely to have prior DVT (P = .001), diabetes mellitus (P = .006), hypertension (P = .003), hyperhomocysteinemia (P = .01), and protein S deficiency (P = .02) when compared to the other groups. The idiopathic DVT was significantly associated with overweight (12.9%) and normal weight (11.3%). The frequency of recurrent DVT was significantly higher in grade I obesity (P = .001) when compared to other groups (Figure 2). Moreover, the least mortality rate was seen in obese III (6%), followed by obese II (12%), obese I (19%), overweight (29%), and normal weight (34%).
Table 2.
Patients Demographics and Clinical Characteristics of DVT Based on the Body Mass Index.
| G1 | G2 | G3 | G4 | G5 | P | |
|---|---|---|---|---|---|---|
| n (%) | 151 (22.8%) | 186 (28.1%) | 156 (23.6%) | 98 (14.8%) | 71 (10.7%) | |
| Age, mean (SD) | 48 (20) | 50 (18) | 52 (16) | 51 (16) | 51 (15) | .53 |
| Abnormal coagulation | 33 (22.0%) | 33 (17.7%) | 45 (28.8%) | 24 (24.5%) | 22 (31.0%) | .08 |
| History of DVT | 17 (11.3%) | 32 (17.2%) | 41 (26.3%) | 28 (28.6%) | 28 (39.4%) | .001 |
| Protein C deficiency | 13 (8.6%) | 13 (7.0%) | 13 (8.3%) | 13 (13.3%) | 5 (7.0%) | .46 |
| Protein S deficiency | 10 (6.6%) | 11 (5.9%) | 7 (4.5%) | 4 (4.1%) | 11 (15.5%) | .02 |
| Antithrombin III deficiency | 5 (3.3%) | 2 (1.1%) | 9 (5.8%) | 4 (4.1%) | 6 (8.5%) | .05 |
| Hyperhomocysteinemia | 8 (5.3%) | 19 (10.2%) | 4 (2.6%) | 6 (6.1%) | 9 (12.7%) | .01 |
| Factor V Leiden | 3 (2.0%) | 9 (4.8%) | 5 (3.2%) | 2 (2.0%) | 6 (8.5%) | .13 |
| Hypertension | 49 (32.5%) | 53 (28.5%) | 63 (40.4%) | 41 (41.8%) | 37 (52.1%) | .003 |
| Diabetes mellitus | 33 (21.9%) | 41 (22.0%) | 53 (34.0%) | 32 (32.7%) | 28 (39.4%) | .006 |
| History of travel | 5 (3.3%) | 13 (7.0%) | 6 (3.8%) | 3 (3.1%) | 2 (2.8%) | 0.36 |
| Idiopathic DVT | 17 (11.3%) | 24 (12.9%) | 2 (1.3%) | 1 (1.0%) | 0 (0.0%) | .001 |
| Bedridden | 18 (11.9%) | 17 (9.1%) | 14 (9.0%) | 6 (6.1%) | 2 (2.8%) | .20 |
Abbreviations: DVT, deep venous thrombosis; G1, normal weight; G2, overweight; G3, obese I; G4, obese II; G5, obese III; SD, standard deviation.
Figure 2.
Recurrent deep venous thrombosis (DVT) and mortality rates by body mass index (BMI) status.
Predictors of Mortality
Multiple logistic regression analysis (Table 3) after adjusting for age, sex, and other potential relevant covariates showed that diabetes mellitus (OR = 2.49; 95% CI: 1.32-4.69; P = .005), malignancy (OR = 11.00; 95% CI: 6.14-19.69; P = .001), and CFV thrombosis (OR = 2.09; 95% CI: 1.20-3.66; P = .009) were the predictors of mortality in patients with DVT, whereas BMI ≥30 (OR = 0.52; 95% CI: 0.29-0.92; P = .02) was the significant predictor of survival.
Table 3.
Multiple Logistic Regression Analysis for the Predictors of Mortality in Patients With DVT.
| Variables | Age- and Sex-Adjusted Odd Ratio | 95% Confidence Interval | P Value |
|---|---|---|---|
| Recurrent DVT | 0.625 | 0.282-1.382 | .246 |
| History of pulmonary embolism | 1.333 | 0.400-4.440 | .640 |
| Diabetes mellitus | 2.489 | 1.319-4.699 | .005 |
| Dyslipidemia | 0.855 | 0.428-1.707 | .657 |
| Hypertension | 1.542 | 0.797-2.984 | .199 |
| Body mass index ≥30 | 0.522 | 0.295-0.924 | .026 |
| Malignancy | 11.001 | 6.143-19.699 | .001 |
| Posterior tibial vein thrombosis | 1.091 | 0.604-1.970 | .774 |
| Common femoral vein thrombosis | 2.098 | 1.202-3.661 | .009 |
| Iliac vein thrombosis | 0.378 | 0.116-1.230 | .106 |
| Antithrombin III deficiency | 1.832 | 0.464-7.225 | .387 |
Abbreviation: DVT, deep venous thrombosis.
Time to Discharge or Death Analysis
Kaplan-Meier survival (log-rank test) showed no significant difference with respect to mortality among the 5 groups of BMI (P = .126; Figure 3). However, after adjusting for age, sex, PE, and duration of warfarin treatment, Cox regression models showed that BMI ≥40 was an independent predictor of favorable survival among all BMI groups (HR: 0.177, 95% CI: 0.045-0.691, P = .013; Figure 4).
Figure 3.
Kaplan-Meier survival analysis based on body mass index (BMI) status.
Figure 4.
Cox regression analysis according to body mass index (BMI) status. Only obese III (BMI ≥40) has impact on mortality (hazard ratio [HR]: 0.177, 95% confidence interval [CI]: 0.045-0.691, P = .013), after adjusting for age, sex, pulmonary embolism, and duration of Warfarin treatment.
Discussion
This is a large cohort study describing the relationship between BMI and DVT from a rapidly developing Middle Eastern country with a high prevalence of obesity. There are key findings of this study including the substantial association between DVT and high BMI and the peculiar presentation, risk factors, and outcomes in obese patients. The mortality is inversely related to the patients’ BMI. Obese patients have higher frequency of abnormal coagulation factors, recurrent VTE, and distal DVT.
Earlier studies showed more than 2-fold increased risk of VTE in obese when compared to nonobese patients, even after adjusting for age, gender, and metabolic syndrome components.6,9,18 Consistent with previous reports, our study showed that the frequency of recurrent VTE was significantly higher among obese than nonobese patients.8,18,19 However, the German MAISTHRO registry reported a lack of relationship between recurrent VTE and obesity.20 In this registry, obesity and thrombophilia comprised 23% and 51%, respectively, in comparison to 49% and 23.7%, respectively, in our cohort.
The development of DVT is attributed to a complex interaction of genetic and environmental predisposing factors.21 In our series, diabetes mellitus, abnormal coagulation profiles, recurrent VTE, and cardiovascular risks were significantly associated with obesity.
Several epidemiological studies showed an association between metabolic syndrome and VTE.6,22,23 Patients with metabolic syndrome could have a risk of vascular thrombosis because of associated endothelial dysfunction, increased platelet reactivity, and activation of the pro-inflammatory and pro-atherogenic mediators released by adipose cells.23 Obesity as a substantial component of metabolic syndrome may also have elevated plasma levels of Plasminogen activator inhibitor-1 (PAI-1) and fibrinogen and decreased protein C levels.24–26 Furthermore, the prothrombotic features of morbidly obese patients include antithrombin III deficiency in addition to the insulin-resistant status that has been shown to be ameliorated after the medical and surgical treatment of obesity.22–24 Similar to prior data, there was a significant increase in the risk of VTE in patients with deficiency of antithrombin III and protein S in our obese groups.21–24 Notably, obesity may have an increased risk of VTE independent of the metabolic syndrome components, due to the fact that increased BMI might lead to deep venous stasis secondary to the mechanical deterioration in the venous valve system.13
An earlier meta-analysis by Ageno et al6 concluded that the risk of VTE was 2.3 for obesity, 1.5 for hypertension, 1.4 for diabetes mellitus, and 1.2 for dyslipidemia. In our study, patients with grade III obesity were more likely to have diabetes mellitus when compared to the other groups. In a recent meta-analysis with 19 608 patients with thrombosis, patients with BMI ≥30 had a significant higher prevalence of VTE than those with BMI <30 kg/m2 (OR = 2.45).25 Data from Copenhagen City Heart Study showed that obesity and smoking were the predictors of VTE, whereas dyslipidemia and diabetes mellitus were not.26
Anticoagulant therapy with unfractionated heparin followed by warfarin therapy is the primary treatment of acute VTE and to reduce its recurrence.27,28 The optimal dosing strategy of anticoagulant therapy in obese patients is controversial. In the present study, anticoagulant therapy with warfarin and antiplatelets were prescribed more in obese than in nonobese patients. Also, the duration of warfarin therapy was significantly longer in patients with higher BMI than normal weight patients.
From the surgical point of view, venous surgery in obese patients is technically associated with some difficulties, and few studies reported that obesity is associated with increased treatment failure, that is, vessel recanalization.2
A substantial improvement in the manifestations of DVT has been reported after bariatric surgery.2 Stroh et al29 evaluated the risk of DVT in obese patients undergoing primary bariatric procedures and found that BMI and duration of DVT prophylaxis had an impact on the occurrence of DVT, whereas, the type of surgical procedure and use of DVT prophylaxis showed no statistical impact on the incidence of DVT. Patients with DVT prophylaxis duration of ≥14 days showed an increased risk of developing DVT compared to those who had a drug-based prophylaxis of less than 1 week (OR: 3.6; 95% CI: 1.27-10.33).29 However, the latter finding needs further elaboration. Moreover, the authors advocated the use of low-molecular-weight heparin due to its better bioavailability and half-life.
As the number of prospective studies that assessed the VTE prophylaxis and treatment in obese patients is scarce, there is a need for more work to adjust the type, dose, and duration of heparin, and warfarin and to justify the use of mechanical devices in obese patients.2
Patients who survived initial episode of DVT are susceptible to the development of PTS. Ageno et al30 investigated the association between BMI and PTS. The authors reported significant correlation between the initial BMI and the occurrence of PTS; BMI of >28 kg/m2 predicted early onset of PTS. Tick et al31 showed that obese patients had a 1.5-fold increased risk of PTS, with a 1-year cumulative incidence of 34% compared to 22% in patients with normal BMI. In the current study, the incidence of PTS was comparable among obese and nonobese patients. However, we could claim that the definition of PTS may not clearly be reported for each case in our registry.
Pulmonary embolism remains the leading cause of death in patients presenting with DVT; however, there is no clear evidence for the association between obesity and mortality in this regard. Despite the fact that obese patients have more comorbidities, few investigators have reported a lower rate of mortality in obese patients with VTE when compared to nonobese patients, and this phenomenon is referred as obesity paradox.3,32,33 Consistently, in our series, the mortality rate was significantly higher among normal BMI patients in comparison to either obese or overweight patients. However, such phenomenon was not observed in young adults and children who were obese.33,34
Our study has potential limitations due to its retrospective nature.
The evaluation of excess body weight using BMI is a valuable tool to provide a standardized definition of obesity; however, BMI alone may not provide a good estimate of fat distribution in the body. The waist circumference or waist–hip ratio is an appropriate indicator of central obesity in metabolic syndrome; however, none of these 2 variables was given in our DVT database.
Conclusions
Obese patients have higher frequency of DVT with characteristic risk factors, pattern, localization, and complications. However, the mortality rate is significantly higher among nonobese patients, which indicates the involvement of obesity paradox phenomenon. This obesity paradox needs further investigation to assess its clinical and pharmacotherapeutic implications.
Acknowledgments
The authors thank all the staff of the Vascular Surgery at Hamad General Hospital, Qatar, involved in this study.
Authors’ Note: All authors contributed to the creation and approved the manuscript. This study was presented in part at the American College of Surgeons (ACS) Clinical Congress; October 16-20, 2016; Washington. This study was approved by the medical research center at HMC, Doha, Qatar (IRB#15002/15).
Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
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