Mitochondria-DNA copy-number and incident venous thromboembolism among middle-aged women: a population-based cohort study.

Venous thromboembolism (VTE) is the third most common cardiovascular disease. Low amount of mitochondrial DNA copy number (mtDNA-CN) has been associated with arterial cardiovascular disease (CVD) and reflects mitochondrial dysfunctions. However, whether mtDNA-CN is associated with VTE has not been determined. To examine the association between mtDNA-CN and incident VTE among middle-aged women. 6917 women aged 50-64 years, followed for 20 years in the Women's Health In the Lund Area (WHILA) study. DNA samples for mtDNA quantification were available from 2521 women. Quantification of mtDNA-CN was performed using a well-optimized droplet digital PCR method. After exclusions of women with anticoagulant treatment, women living in nursing homes, and women who were diagnosed with cancer, stroke, VTE, or coronary heart disease at baseline, a cohort of 2117 women remained for analysis. Cox regression was used to analyze the relationship between mtDNA-CN and time to VTE (hazard ratio = HR). In total, 87 women were diagnosed with VTE during follow-up, corresponding to an incidence rate of 2.8 per 1000 person-years. Neither crude nor adjusted HR for mtDNA-CN were significantly associated with incident VTE. A sensitivity analysis with inclusion of excluded women did not change the results. MtDNA-CN was not significantly associated with VTE. The present study suggests that mtDNA-CN, reflecting mitochondrial dysfunction, should not be considered a biomarker that plays a major role for developing VTE. However, due to limited study size we may not exclude minor associations.