Venous thromboembolism after community-acquired bacteraemia: a 20-year Danish cohort study

BACKGROUND: Infections may increase the risk for venous thromboembolism (VTE), but little is known about VTE risk associated with community-acquired bacteraemia (CAB). We examined the risk for VTE within one year of CAB in comparison to that in matched controls.

METHODS: We conducted a population-based cohort study in North Denmark 1992-2011, using data from high-quality health-care databases. We included 4,213 adult CAB patients who had positive blood cultures drawn on the day of hospital admission, 20,084 matched hospitalised controls admitted for other acute medical illness, and 41,121 matched controls from the general population. We computed 0-90 and 91-365 day absolute risks for hospital-diagnosed VTE and used regression analyses with adjustment for confounding factors to compare the risk for VTE in bacteraemia patients and controls.

RESULTS: Among CAB patients, 1.1% experienced VTE within 90 days of admission and 0.5% during 91-365 days after admission. The adjusted 90-day odds ratio (OR) for VTE was 1.9 (95% CI 1.4-2.7) compared with hospitalised controls, and 23.4 (95% CI 12.9-42.6) compared with population controls. During 91-365 days after CAB admission, the VTE risk remained moderately increased (adjusted hazard ratio vs. hospitalised controls, 1.4; 95% CI 0.8-2.5, and vs. population controls, 1.9; 95% CI 1.0-3.3). Compared to hospitalised controls, the 90-day VTE risk increase was greater for Gram-positive infection (adjusted OR 2.5; 95% CI 1.6-4.1) than for Gram-negative infection (adjusted OR, 1.2; 95% CI 0.7-2.1), partly due to a high risk after Staphylococcus aureus infection (3.6%).

CONCLUSION: The risk for VTE is substantially increased within 90 days after community-acquired bacteraemia when compared to hospitalised controls and population controls. However, the absolute risk of VTE following CAB is low.