The Epidemiology of Venous Thromboembolism in Alberta, Canada: A Population Based Cohort Study.

  • The Epidemiology of Venous Thromboembolism

  • Author / Creator
    Alotaibi, Ghazi S
  • Background: Venous thromboembolism (VTE), comprises both deep vein thrombosis (DVT) and pulmonary embolism (PE). It is a common acute cardiovascular event associated with increased long-term morbidity, disability, all-cause mortality, and high rates of recurrence. Major advances in diagnosis, prophylaxis, and treatment over the past 3-decades have likely changed its clinical epidemiology. However, there are little published data describing contemporary, population-based, trends in VTE epidemiology. Objectives: To examine recent trends in the epidemiology of clinically recognized VTE and assess the disease burden in the Canadian province of Alberta. Methods: Initially, we developed and validated a VTE case identifying algorithm using a combination of International Classification of Diseases (ICD) diagnostic codes and a VTE related imaging procedure codes against patient charts. Then, two retrospective cohort studies based on linkage of administrative health databases in Alberta, Canada, provided estimates of VTE incidence and case fatality over the past decade. Also, we investigated the effect of cancer on overall, short- and long-term mortality in a cohort of consecutive incident PE patients. Poisson regression and Cox’s proportional hazard models were used in the multivariate analysis. Results: 1361 patients were used for the validation of the case-definition. The sensitivity and specificity of our algorithm for identifying patients with VTE using administrative data is 75% (95% CI: 69.18-80.22) and 93.78% (92.19-95.13), respectively. Subsequently, we identified 31,656 cases of acute symptomatic VTE between April 1, 2002, and March 31, 2012. The age and sex adjusted incidence rate of VTE was 1.38 (95% CI: 1.37, 1.40) per 1000 person-years. For pulmonary embolism it was 0.38 (95% CI: 0.36, 0.40) per 1000 person-years and for deep vein thrombosis it was 1.0 (95% CI: 0.99, 1.1) per 1000 person-years. The adjusted model showed no significant change in the incidence of VTE during the study period. The 30-day case fatality rate of VTE was 2.0% (95% CI: 1.89, 2.21) and was almost doubled in patients with PE 3.9% (95% CI: 3.50-4.33). The 1-year case fatality was 9.2% (95% CI: 8.88-9.52) for VTE and 12.9% (95% CI: 12.2-13.6) for patients with PE. In patients with PE, The 1-year and 5-year survival probabilities were 61% (95% CI: 57-64) and 39% (95% CI: 36-43) in cancer-associated PE patients, 93% (95% CI: 92-94) and 80% (95% CI: 78-81) in provoked PE patients, and 94% (95% CI: 93-95) and 85% (95% CI: 83-87) in unprovoked PE patients, respectively. Compared to patients with unprovoked PE events both short-term and long-term survival in patients with cancer-associated PE have significantly higher observed risk of all-cause mortality in all age groups, P-value <0.001. In contrast, patients with provoked events had similar short- and long-term hazard of death. Conclusion: Venous thromboembolism is a disease with significant morbidity and mortality. Despite advances in identification, prophylaxis, and treatment in the last decade, the disease burden remains high. While this may be partially due to increased sensitivity of diagnostic methods, especially for PE, it may also imply that current prevention and treatment strategies are less than optimal.

  • Subjects / Keywords
  • Graduation date
    Spring 2016
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Wu, Cynthia (Medicine)
    • Kaul, Padma (School of Public Health)
    • Carrier, Marc (University of Ottawa)
    • Senthilselvan, Ambikaipakan (Sentil) (School of Public Health)
    • Voaklander, Donald (School of Public Health)