Venous Blood Clots Do Not Increase Mortality in Scleroderma Patients, Study Shows

The occurrence of blood clots in the veins of scleroderma patients is rare and does not change patients’ survival rates, a new Canadian study shows.

Still, researchers see a need for improved understanding of venous thromboembolism (VTE) in these patients.

The study, “Venous Thromboembolism in Systemic Sclerosis: Prevalence, Risk Factors, and Effect on Survival,” was published in The Journal of Rheumatology.

Scleroderma is characterized by lesions in blood vessels, inflammation, and fibrosis (scarring). Systemic inflammation may lead to VTE, which refers to blood clots that start in a vein. VTE is the third leading vascular diagnosis in the U.S., after heart attack and stroke.

Scientists have suggested that scleroderma may be an under-recognized risk factor for VTE, but the current available evidence is inconclusive.

Previous research showed that patients with inflammatory rheumatic diseases have a higher risk of VTE than the general population. But specific data on scleroderma is limited by the inclusion of other autoimmune diseases in the studies or by an experimental bias consisting of preferentially analyzing severely ill patients.

Results from administrative studies revealed that scleroderma patients had an increased risk of developing deep vein thrombosis — DVT, which are blood clots starting in deep veins, usually in the legs — and pulmonary embolism (a blood clot in a lung artery), but these analyses may have included cases of systemic lupus erythematosus or overlap syndromes.

The current study evaluated whether scleroderma leads to a higher risk of VTE. Scientists compared the incidence of VTE in patients to that of the general population, while also assessing risk factors for the development of VTE and its effect on survival in scleroderma patients. The study period was from 1970-2017.

The research included 1,181 scleroderma patients, 971 of them women and 210 of them men.

Results showed that 40 patients (3.4%) had VTE events. However, the incidence of VTE in these patients was not higher than in the general population; the cumulative incidence of VTE was 2.7 per 1,000 patient-years.

“This suggests that unlike other rheumatologic disease such as rheumatoid arthritis and systemic lupus erythematosus, [scleroderma] is not an independent risk factor for VTE,” researchers wrote.

Pulmonary arterial hypertension (PAH), peripheral arterial disease (which reduces blood flow to the limbs), and the presence of the antibodies Scl-70 and anticardiolipin, which are common in patients with scleroderma and other autoimmune disorders, were found to be predictors of VTE.

Results also showed that 440 scleroderma patients in the study died during the study period. But having VTE did not bring about a difference in survival. PAH and interstitial lung disease were, however, predictors of mortality.

“VTE is an infrequent but important occurrence in [scleroderma]. Improving our understanding about the burden and causes of VTE in [scleroderma] has the potential to prevent and reduce morbidity and mortality from VTE,” researchers wrote.