Rheumatoid arthritis may double VTE risk

Janis C Kelly

August 14, 2013

Taichung, Taiwan - Rheumatoid arthritis (RA) was associated with a significantly increased risk for potentially fatal blood clots in the legs and lung in a nationwide prospective cohort study from Taiwan published online August 7, 2013 in the Annals of the Rheumatic Diseases[1] . Venous thromboembolism (VTE) prophylaxis should be considered for patients with RA who are facing additional risk factors, such as surgery or hospitalization, authors say.

Dr Wei-Sheng Chung (Central Taiwan University of Science and Technology, Taichung) and colleagues analyzed data from a cohort of 29 238 patients with RA and 116 952 matched control subjects drawn from the Taiwan National Health Insurance Research Database (NHIRD).

They found that patients with RA were more than three times as likely to develop deep venous thrombosis (DVT) during the four years after diagnosis as control subjects (p<0.001), after adjusting for age, sex, and comorbidities. Moreover, the patients with RA were twice as likely to develop pulmonary embolism (PE) as those without RA (p<0.001).

"Clinicians should be aware of these findings. To take holistic care of RA patients, a multidisciplinary team work approach is warranted," corresponding author Dr Chia-Hung Kao (China Medical University Graduate Institute of Clinical Medicine Science, Taichung, Taiwan) said in an interview.

Excess clot risk highest for those younger than 50 years

RA was associated with particularly high risk in those younger than 50 years, who were almost six times as likely to develop DVT and more than three times as likely to develop PE as control subjects.

The researchers tracked the health of nearly the entire population of Taiwan (23.74 million) through the country's compulsory national insurance scheme between 1998 to 2008 and included a further monitoring period to the end of 2010 to find out whether RA increased the risk for potentially fatal blood clots. The authors note that VTE has had a 30-day case fatality rate ranging from 11% to 30% in previous studies.

In the current study, patients with RA also were more likely to have other underlying, potentially treatable, conditions such as hypertension, diabetes, high cholesterol, or heart failure, which might contribute to the increased thromboembolism risk. However, Kao emphasized, the increased risk was apparent even after adjustment for age and comorbidities.

US data show similar RA-related blood clot risk

Commenting on the study, Dr Seoyoung C Kim (Brigham and Women's Hospital, Harvard Medical School, Boston, MA) noted that the new results were consistent with previous studies, including one by Kim's own group [2].

"Over the past few years, a number of studies, including ours and this one, showed an increased risk of VTE in patients with RA compared with those without RA. This risk may be related to RA disease (systemic inflammation) itself or the treatment that patients receive for RA. Regardless, physicians should keep in mind that patients with RA are at an increased risk of VTE," Kim said. She advised that patients with RA be placed on VTE prophylaxis when undergoing surgery or hospitalization, both of which also increase risk, or if they develop cancer.

"In our study, the majority of patients who developed VTE had a provoking event such as a new diagnosis of cancer, hospitalization, or surgery," Kim said.

The study was supported by grants from the study hospital, the Taiwan Department of Health Clinical Trial and Research Center of Excellence , the Taiwan Department of Health Cancer Research Center of Excellence , and the International Research-Intensive Centers of Excellence in Taiwan. The authors have disclosed no relevant financial relationships. Kim received research support from Pfizer and tuition support for the pharmacoepidemiology program at the Harvard School of Public Health funded by Pfizer and ASIS A.

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