Prevalence and Risk Factors of Venous Thromboembolism in Hospitalized Pediatric Patients
Condition: Venous Thromboembolism; Deep Venous Thrombosis; Pediatrics
MeSH terms: Thrombosis; Thromboembolism; Venous Thromboembolism; Venous Thrombosis
Study type: Observational

Summary: 
      The issue to be studied is the prevalence of venous thromboembolism (VTE) in hospitalized
      pediatric patients, and to identify if there are subgroups of patients who may be at higher
      risk.

      There are two hypotheses that will be looked at in this study. The first hypothesis is that
      individual risk factors for VTE in hospitalized pediatric patients are: age >14, obesity,
      black race, female sex, presence of a central venous line (CVL), traumatic mechanism of
      injury, orthopaedic surgery, and use of oral contraceptives.

      The second hypothesis is that risk factors have an additive effect such that risk
      stratification can be developed to identify those patients with the highest risk.
    

Detailed description: 
      Venous thromboembolism is a well recognized concern in the hospitalized adult population:
      11-15% of medically ill adults will have venous thromboembolism (VTE) and 4-5% will develop a
      proximal DVT in the absence of prophylaxis.6 Furthermore, these diagnosed events are an
      underestimation of the prevalence of VTE as 80% are clinically silent.6 VTE risk
      stratification exists for adult populations and prophylaxis against VTE is standard
      procedure. While VTE occurs less frequently in pediatric populations, the incidence is on a
      rise. Vu et al report a significant increase in DVT in 2003 compared to 1997 using data from
      the Health Care Cost and Utilization Project Kids' Inpatient Database. 2 If one were to
      extrapolate the known adult risk factors for VTE to children, this rise could be attributed
      to an increase in childhood obesity ,4 an increase in estrogen-based therapy among teenage
      girls1, or the increase in pediatric trauma.3 However, few studies have been performed to
      show if these or other identified adult risk factors are indeed pediatric risk factors as
      well. Due to this lack of knowledge of risk factors for VTE in pediatric populations, there
      are minimal guidelines for when physicians should provide prophylactic treatment or even have
      heightened awareness of the possibility of VTE in their pediatric patient. Furthermore, there
      are scant published guidelines regarding which type of prophylactic treatment is safe and
      efficacious in the pediatric population, nor are there guidelines regarding the treatment of
      established VTE. Outcomes of prophylactic treatment will not be able to be evaluated
      accurately until the measures are undertaken in patients with identified high risk.
      Identification of high risk groups and subsequent prevention of VTE is important due to the
      significant morbidity and mortality associated with VTE. Vu et al report a two-fold increase
      in in-hospital death in pediatric patients with an identified VTE compared to those without
      one. This risk was independent of other comorbid conditions.2 Morbidity includes pulmonary
      embolism, recurrent thrombosis, and postphlebitic syndrome (characterized by swelling, pain,
      skin indurations and pigmentation caused by incompetent venous valves). Due to the younger
      age of onset, pediatric patients with these morbidities live with the consequences for a much
      longer period of time; furthermore, they may experience secondary consequence such as limb
      length discrepancies, etc.

      Currently there is a sharp delineation in prophylaxis strategy as defined merely by age. As
      soon as a patient is 18 he is assessed by risk stratification models and given prophylaxis if
      he meets these criteria. A patient just one year younger, however, is left unevaluated due to
      the lack of criteria for VTE risk in pediatric patients. The patient may fit height and
      weight averages of a full grown adult, and may possess many of the criteria used to assess an
      adult for VTE risk. He still may not be offered prophylaxis treatment due to his age alone.
      This assumes age is the best predictive factor of VTE in the younger patient. However, few
      studies have been done assessing what risk factors truly exist for the pediatric patient, and
      those that have, suggest that there are other factors that play into the equation, and may
      even be more important.5 Due to potential complications from both VTE as well as prophylaxis,
      and the increasing prevalence of VTE in pediatric populations, studies regarding risk factors
      and safety/efficacy of prophylactic treatment are needed to establish guidelines of care.
    

Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients aged <18 years old, who were hospitalized at MSHMC from January 1, 2000 -December
        31, 2008 with documented VTE in one of three databases:

          1. Vascular lab duplex ultrasound database

          2. Inpatient hospital admission/discharge ICD-9 database

          3. PTSF pediatric trauma database
      
Keywords: venous thromboembolism; duplex ultrasound; pediatric population; Vascular lab duplex ultrasound database; Inpatient hospital admission/discharge ICD-9 database; PTSF pediatric trauma database