CDC project informs efforts to understand and monitor number of people affected by blood clots in US

Multi-cultural group of people, male and female

The actual number of people affected by VTE (blood clots) in the United States is uncertain and reported estimates vary widely, ranging from 350,000 to 900,000 cases per year. Further, the estimated number of people who die each year from blood clots is from 100,000 to 300,000. Unfortunately, current estimates are not precise because they are based on studies in counties that are not representative of the U.S. population and they may underestimate the true occurrence of VTE. VTE is a significant public health problem, but it is also preventable! In order to better guide VTE prevention efforts and save lives, it is important to understand the true number of people affected by VTE in the United States.

About this Study

CDC funded the College of Public Health at the University of Oklahoma Health Sciences Center to develop and conduct a project to monitor the occurrence of VTE in Oklahoma County. The goals of the project were to implement new approaches to provide valid estimates of

  • The number of people with a first-time VTE
  • The number of people who developed a VTE that was treated successfully, but later re-occurred
  • The number of people who died from a VTE
  • The number of people who had a VTE caused by a known event or risk factor (Provoked VTE)
  • The number of people who had a VTE where no identifiable cause or provoking event was evident (Unprovoked VTE)

What is Venous Thromboembolism (VTE)?

Venous thromboembolism includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), and is an important and growing public health issue.

What is Deep Vein Thrombosis (DVT)?

Deep Vein Thrombosis is a condition in which blood clots form in the deep veins of the body.

What is Pulmonary Embolism (PE)?

Pulmonary Embolism occurs when a clot breaks free and blocks the arteries of the lungs.

This study published in the American Heart Journal used multiple methods to collect and link data from a variety of sources to capture inpatient, outpatient, and death-related VTE events in Oklahoma County during the period April 1, 2012 to March 31, 2014. The population in Oklahoma County is representative of the racial/ethnic diversity of the U.S. population (except for a higher percentage of American Indians, 7.7% versus 1.7% for the United States overall).

The purpose of this paper is to describe the development of population-based monitoring for VTE and the methods that were used to conduct the monitoring.

We invite you to read the study’s abstract or full text [PDF – 3.59MB] here.

Main Findings

  • A key and unique feature of the data collection effort was working with the Oklahoma State Commissioner of Health, who made VTE diagnoses reportable conditions for 2010 through 2015, and permitted the College of Public Health to conduct VTE monitoring.
  • The methods of the VTE monitoring system were designed to maximize the number of cases of VTE identified in Oklahoma County:
    • All 13 inpatient facilities in Oklahoma County and the Oklahoma City VA Medical Center were included in this data monitoring system.
    • Fifty six outpatient facilities were identified as being potentially eligible to be included in the data monitoring system. After contacting each facility, only eight of these actually met the criteria to be included and contributed their data to the monitoring system.
  • As of February 1, 2015, 54,494 records of imaging studies (special ultrasound, x-ray, or magnetic resonance tests used to diagnose VTE) were successfully reviewed for the diagnosis (99.5% of all identified imaging records), demonstrating an exceptionally high rate of evaluation of potential cases of VTE.
  • Among the reviewed records, a total of 2,725 cases of VTE were identified. Of these, 8.4% were identified from outpatient facilities, indicating the importance of including VTE identified outside of the hospital when assessing VTE occurrence.

Critical Gaps & Future Directions

Share with Your Friends

CDC and OUHSC joined forces to better understand VTE burden (occurrence) in Oklahoma County.

Currently, there is no national monitoring system for VTE, making it difficult to understand the true burden of VTE in the United States. The methods and results of this project will help inform future efforts to develop valid U.S. estimates of VTE burden and will help guide VTE prevention efforts. The findings from this project will help researchers establish valid estimates of the number of people affected by VTE in Oklahoma County (including associated rates of illness and death), describe characteristics of the affected population and their VTE events, and characterize current VTE prevention efforts.

More Information

Please visit the following links for more information about
Venous thromboembolism:
Healthcare-associated venous thromboembolism:

Paper Reference

Wendelboe AM, Campbell J, McCumber M; Bratzler D; Ding K, Beckman M, Reyes N; Raskob G. The Design and Implementation of a New Surveillance System for Venous Thromboembolism using Combined Active and Passive Methods. American Heart Journal. 2015 [Epub ahead of print].