Susan R. Kahn, MD, MSc; Ian Shrier, MD, PhD; Jim A. Julian, MMath; Thierry Ducruet, MSc; Louise Arsenault, BA; Marie-José Miron, MD; Andre Roussin, MD; Sylvie Desmarais, MD; France Joyal, MD; Jeannine Kassis, MD; Susan Solymoss, MD; Louis Desjardins, MD*; Donna L. Lamping, PhD; Mira Johri, PhD; and Jeffrey S. Ginsberg, MD. (2008) Determinants and Time Course of the Postthrombotic Syndrome after Acute Deep Venous Thrombosis. Annals of Internal Medicine. Volume 149 Issue 10. Pages 698-707
There are limited longitudinal studies to address the reason why some patients suffer from deep venous thrombosis (DVT) develop the postthrombotic syndrome. Therefore, the researchers were interested in identifying the risk factors of developing postthrombotic syndrome in patients with acute DVT. The purpose of the study was to determine the severity, frequency, time course, clinical, and genetic factors of postthrombotic syndrome after acute DVT.
The targeted audience is the clinical fraternity of doctors, nurses and physicians dealing with patients who are vulnerable to postthrombotic syndrome. The study provides longitudinal data which is clinically relevant on the occurrence of prognosis following venous thrombosis so that enhanced preventive and treatment strategies can be adopted for the postthrombotic syndrome by the treating physicians.
The study is a prospective, multicenter cohort study which was conducted by including three hundred and eighty-seven patients who were objectively diagnosed with symptomatic DVT. The researchers listed the demographic, clinical, and index DVT variables listed as predictors of postthrombotic syndrome were based on priori hypothesis and previous published reports. The researchers used well-defined criteria to include and exclude subjects from broad settings. The Villalta scale was tested to be valid from previously published studies to measure the severity of postthrombotic syndrome.
It also has good-to-excellent interobserver reliability. All trained evaluators were unaware of the status of patients’ postthrombototic syndrome and previous severity score. The results were thought to be statistical significant because all p values are less than 0.05. The researchers recognized that this is the first prospective, and longitudinal study that investigated frequency, time course, and severity of postthrombotic syndrome. There were limitations of determining the impact of antcoagulate on Villalta score and further studies are needed. The researchers also suggested new studies about the influence of compression stockings on postthrombotic syndrome.
The researchers stated the strength of the study was that it examined broad demographic and clinical source sample from multi-center. However, the researchers were unable to interpret the correlation between longer duration of warfarin use and higher Villalta severity score due to international normalized ratio inaccessibility. Prescription of compression stockings was determined by the treating physicians. Therefore, the researchers could not directly determine the effect of use of compression stockings on postthrombotic syndrome.
The 387 subjects who were diagnosed with DVT of the lower limb in the preceding 7 days in the emergency department, outpatient, and inpatient settings of 8 hospitals were invited to participate in the study. The effects of clinical, demographic, genetic, and index DVT characteristics were assessed on the development of postthrombotic syndrome (Villalta scale) at 1, 4, 8, 12 and 24 months after the patients were enrolled. Patients were excluded if his/her estimated life expectancy was less than 3 months and if they were unable to return for follow up. The informed consent forms were obtained from eligible participants.
The results showed that approximately 30%, 10%, and 3% of patients progressed to mild, moderate, and severe postthrombotic syndrome respectively at each study intervals (5 study visits). The patients who had highest postthrombotic severity score during 1-month follow up had higher mean Villalta score over 24 months.
The researchers identified the predictors which produced higher score of severity during the follow up: older age (0.30 increase in score per 10-year age; P=0.011), higher body mass index (BMI)(0.14 increase per 1-kg/m2; P0.001), female (0.79 increase; in score P=0.020), proximal venous thrombosis (2.23 increase in score for common femoral or iliac venous thrombosis compared to distal venous thrombosis; P0.001), and recurrent ipsilateral DVT (1.78 increase in score compared to no previous ipsilateral DVT); P=0.001), longer warfarin use (0.09 increase in score; P0.001). Use of compression stockings did not correlate with Villalta score. The study also showed that 1-month predictors produced similar results for the following visits.
The researchers concluded that acute DVT manifests quickly and occurs frequently to postthrombotic syndrome within a month of diagnosis. Patients who have more severe postthrombotic scores during 1-month will have poorer outcome later on. Older age, higher BMI, female sex, thrombosis of iliac vein and femoral vein, previous ipsilateral DVT are variables predict development of postthrombotic syndrome.
This study provided clinical data about potential risk factors of developing postthrombotic syndrome after acute DVT. Given these findings, I can conclude that the patient is at high risk of developing postthrombotic syndrome due to his age and obesity (high BMI). The study also showed that the risk of recurrent venous thrombosis was higher in patients who are men and had recent surgery, fracture, or plaster casting of leg. The patient who suffered ankle fracture and pneumonia is susceptible to develop recurrent venous thrombosis. Understanding the predictors after acute DVT, we should emphasize the need for better therapeutic strategies to prevent postthrombotic syndrome and recurrent venous thrombosis.