medwireNews: Individuals with rheumatoid arthritis (RA) are at an increased risk for venous thromboembolism (VTE), research confirms.
Among patients with prevalent RA, the rate of VTE was 5.9 cases per 1000 person-years compared with 2.8 cases per 1000 person-years in the general population, a statistically significant difference giving a hazard ratio of 2.0.
In the first year after hospitalization for RA, however, the risk for VTE did not significantly differ from that of individuals without RA. In this first year, the VTE rate was 11.8 events per 1000 person-years versus 13.1 per 1,000 person-years in controls.
"Hospitalization is a strong risk factor for VTE in the general population and in patients with RA, but the short-term (<1 year after hospital discharge) rates for VTE are similar in both groups," explain Marie Holmqvist (Karolinska Institute, Stockholm, Sweden) and colleagues in the Journal of the American Medical Association.
Included in the prospective, population-based study were 37,856 individuals with prevalent RA, 7904 individuals with incident RA, and equal numbers of matched individuals from the general population.
Of those with prevalent RA, 2.2% of individuals had a VTE event after the index date compared with 1.1% of matched individuals.
By the time of RA symptom onset, 1.9% of patients with RA and 1.6% of matched individuals in general population cohort had a history of VTE, a nonsignificant difference.
Over a median follow up of 5.8 years, 2.8% of patients with RA and 1.7% of individuals in the comparison group had a VTE event. This translated into an event rate of 4.5 per 1000 person-years for those with RA and 2.8 per 1000 patient-years in the general population, a statistically significant difference.
In the incident RA cohort, an analysis stratified by time since the RA diagnosis showed similar risks of VTE versus the general population that were similar throughout the follow-up period.
For example, in the RA cohort, the rate of VTE 1 year after diagnosis was 3.8 per 1000 person-years versus 2.4 in the general population cohort, a significant difference that did not increase further in the 10 years following diagnosis.
Past studies have suggested patients with RA might be at a heightened risk for VTE during or after hospitalization because acute inflammation promotes a hypercoagulable state.
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