Risk Factors of Thromboembolic Events and the Impact on Survival in Newly Diagnosed Breast Cancer Patients: An Experience from Taiwan

Hsieh, Pi-Ching

Purpose:

Thromboembolic events (TEEs) are one of the major complications of breast cancer patients and associate with increased mortality. These events have been included as the Core Measure Set by Joint Commission International for the international hospital evaluation in 2013. However, few evidence-based data are available on the development of TEEs in breast cancer patients in Taiwan.

Methods:

Using the National Health Insurance Research Database between 1997- 2010 in Taiwan, we conducted a retrospective cohort study to evaluate 2-year incidence of TEEs and risk factors on 2000-2008 breast cancer cohorts. Matching based on the propensity of age and co-morbidity was used to identify the patients with and without TEEs groups. An accelerated failure time model was applied to analyze the effect of TEEs on death within 2 years after breast cancer diagnosis.

Results:

A total of 80598 patients with breast cancer between 2000 and 2008, the 2-year cumulative TEEs incidence was 1.78% (95% CI = 1.74-1.82), with a rate of 1.38 and 0.43 events/100 patient-years during the first and second half year, respectively. In multivariate model, significant predictors of developing TEEs within 2 years were: age (adjusted incidence rate ratio [adj. IRR] = 3.87 if ≧65 year v＜45; 95% CI = 3.80-3.93), co-morbidity (adj. IRR = 1.96 if ≧3 v 0, 95% CI = 1.93-2.00), hypertension history (adj. IRR = 1.43 if yes v no, 95% CI = 1.41-1.45), breast surgery (adj. IRR = 1.47 if yes v no, 95% CI = 1.45-1.49), radiotherapy (adj. IRR = 1.29 if yes v no, 95% CI = 1.28-1.31), chemotherapy (adj. IRR = 1.40 if yes v no, 95% CI = 1.38-1.42), hormone therapy (adj. IRR = 0.92 if yes v no, 95% CI = 0.91-0.94), and type of hospital (adj. IRR = 1.13 if district v medical center 95% CI = 1.11-1.15). In AFT model analysis, after controlling the characteristics of patient, treatment, hospital, TEE was a significant predictor of decrease 2-year survival (adjusted rate ratio [adj. RR = 2.55, 95 % CI = 2.24-2.91).

Conclusion:

Approximate 1.78% of breast cancer patients developed TEEs within 2 years, with the highest incidence in the first 6 months after diagnosis. Age, co-morbidity, hypertension history, breast surgery, radiotherapy, chemotherapy, and type of hospital level were the significant predictors. Breast cancer patients with TEEs were associated with a higher risk of death within 2 years.