Cardiorespiratory fitness and future risk of venous thromboembolism.

Background: Cardiorespiratory fitness (CRF) is a strong predictor of future arterial cardiovascular disease and premature mortality. However, there are limited data on the association between CRF and the risk of incident venous thromboembolism (VTE).

Objectives: To investigate whether estimated CRF (eCRF) was associated with the risk of incident VTE in a cohort recruited from the general population.

Methods: Participants (n = 10 393) from the sixth survey of the Tromsø Study (2007-08) were included, and incident VTEs were recorded up to 31 December 2016. CRF was estimated in sex-specific algorithms based on age, waist circumference, resting heart rate, and self-reported physical activity. Hazard ratios (HRs) with 95% confidence intervals (CIs) of VTE according to categories of eCRF were estimated in Cox regression models adjusted for sex with age as timescale. The impact of weight status was evaluated in analyses stratified by weight category.

Results: There were 176 incident VTEs during follow-up. Compared with individuals with eCRF < 85% of age-predicted, those with eCRF of 85% to 100% and >100% of age-predicted had 46% (HR 0.54; 95% CI 0.39-0.77) and 67% (HR 0.33; 95% CI 0.20-0.54) lower VTE risk, respectively. Compared with overweight/obese individuals with eCRF < 85% of age-predicted, overweight/obese individuals with eCRF ≥ 85% had 50% (HR 0.50, 95% CI 0.35-0.74) lower risk, and normal weight individuals with eCRF ≥ 85% had 55% (HR 0.45, 95% CI 0.30-0.68) lower risk.

Conclusions: Higher eCRF was associated with lower risk of incident VTE. The association was independent of weight categories, suggesting that higher eCRF may modify the association between obesity and VTE.